[Federal Register Volume 77, Number 73 (Monday, April 16, 2012)]
[Proposed Rules]
[Pages 22637-22662]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2012-9065]

[[Page 22637]]

Vol. 77


No. 73

April 16, 2012

Part II

Department of Transportation


National Highway Traffic Safety Administration


49 CFR Part 571

Federal Motor Vehicle Safety Standards; Accelerator Control Systems; 
Proposed Rule

Federal Register / Vol. 77 , No. 73 / Monday, April 16, 2012 / 
Proposed Rules

[[Page 22638]]



National Highway Traffic Safety Administration

49 CFR Part 571

[Docket No. NHTSA-2012-0038]
RIN 2127-AK18

Federal Motor Vehicle Safety Standards; Accelerator Control 

AGENCY: National Highway Traffic Safety Administration (NHTSA), 
Department of Transportation (DOT).

ACTION: Notice of proposed rulemaking (NPRM).


SUMMARY: In this NPRM, we (NHTSA) propose to revise the Federal Motor 
Vehicle Safety Standard for accelerator control systems (ACS) in two 
ways. First, we propose to amend the Standard to address more fully the 
failure modes of electronic throttle control (ETC) systems and also to 
include test procedures for hybrid vehicles and certain other vehicles. 
This part of today's proposal is related to an NPRM that NHTSA 
published in 2002.
    Second, we propose to add a new provision for a brake-throttle 
override (BTO) system, which would require that input to the brake 
pedal in a vehicle must have the capability of overriding input to the 
accelerator pedal. This BTO proposal is an outgrowth of NHTSA's 
research and defect investigation efforts aimed at addressing floor mat 
entrapment and related situations.\1\ We propose to apply the 
requirement for BTO systems to new passenger cars, multipurpose 
passenger vehicles, trucks and buses that have a gross vehicle weight 
rating of 10,000 pounds (4,536 kilograms) or less and ETC.

    \1\ Accelerator pedal entrapment is a particular category of 
``unintended acceleration.'' The latter is the general term we use 
to refer broadly to any vehicle acceleration that a driver did not 
purposely cause to occur.

DATES: Comments must be received on or before June 15, 2012.

ADDRESSES: You may submit comments to the docket number identified in 
the heading of this document by any of the following methods:
     Federal eRulemaking Portal: Go to http://www.regulations.gov. Follow the online instructions for submitting 
     Mail: Docket Management Facility, M-30, U.S. Department of 
Transportation, West Building, Ground Floor, Rm. W12-140, 1200 New 
Jersey Avenue SE., Washington, DC 20590.
     Hand Delivery or Courier: West Building Ground Floor, Room 
W12-140, 1200 New Jersey Avenue SE., between 9 a.m. and 5 p.m. Eastern 
Time, Monday through Friday, except Federal holidays.
     Fax: (202) 493-2251.
    Regardless of how you submit your comments, you should mention the 
docket number of this document.
    You may call the Docket at 202-366-9324.
    Instructions: For detailed instructions on submitting comments and 
additional information on the rulemaking process, see the Public 
Participation heading of the Supplementary Information section of this 
document. Note that all comments received will be posted without change 
to http://www.regulations.gov, including any personal information 
    Privacy Act: Please see the Privacy Act heading under Rulemaking 
Analyses and Notices.

FOR FURTHER INFORMATION CONTACT: For non-legal issues, Mr. Michael 
Pyne, Office of Crash Avoidance Standards (telephone: 202-366-4171) 
(fax: 202-493-2990). Mr. Pyne's mailing address is National Highway 
Traffic Safety Administration, NVS-112, 1200 New Jersey Avenue SE., 
Washington, DC 20590.
    For legal issues, Mr. William Shakely, Office of the Chief Counsel 
(telephone: 202-366-2992) (fax: 202-366-3820). Mr. Shakely's mailing 
address is National Highway Traffic Safety Administration, NCC-112, 
1200 New Jersey Avenue SE., Washington, DC 20590.


Table of Contents

I. Executive Summary
II. Introduction
III. Safety Need for Brake-Throttle Override Systems
    A. Inability To Stop a Moving Vehicle in a Panic Situation
    B. How Trapped-Pedal Scenarios May Lead to Crashes
    C. Loss of Power Brake Boost Requires Greater Brake Pedal Force
    D. Description of Brake-Throttle Override
IV. Technical Discussion of Accelerator Control System Safety Issues
    A. Accelerator Control System Disconnections
    B. Electronic Throttle Control
    C. Potential ETC Failures Not Covered
V. Proposed Update of FMVSS No. 124 Test Procedures
    A. Purpose and Scope of FMVSS No. 124 at Present
    B. Need for Update of FMVSS No. 124
    C. Applicability to Electronic Throttle Control Components
    D. Test Procedures of the 2002 NPRM
    E. Powertrain Output Test Procedures and ``Creep Speed''
    F. Comments on the 2002 NPRM
VI. Notice of Proposed Rulemaking
    A. Definition of Electronic Throttle Control System
    B. Brake-Throttle Override Equipment Requirement
    C. Brake-Throttle Override Performance Requirement
    D. Update of FMVSS No. 124 Disconnection Test Procedures
    E. Compliance Options for Various Vehicles
VII. Safety Benefits and Crash Data
    A. Summary of Crash Data on Accelerator Control Issues
    B. Owner Complaint Data
VIII. Cost, Lead Time, and Other Issues
    A. Cost of the Proposed BTO Requirement
    B. Proposed Lead Time and Phase-In
    C. Vehicles Over 10,000 lb GVWR
    D. Manual Transmission Vehicles
    E. Proposed New Title for FMVSS No. 124
IX. Rulemaking Analyses and Notices
    A. Executive Orders 12866, 13563, and DOT Regulatory Policies 
and Procedures
    B. Regulatory Flexibility Act
    C. Executive Order 13132 (Federalism)
    D. National Environmental Policy Act
    E. Paperwork Reduction Act
    F. National Technology Transfer and Advancement Act
    G. Executive Order 12988
    H. Unfunded Mandates Act
    I. Executive Order 13045
    J. Executive Order 1211
    K. Plain Language
    L. Regulation Identifier Number (RIN)
    M. Privacy Act
X. Public Participation

I. Executive Summary

    NHTSA is proposing to amend Federal Motor Vehicle Safety Standard 
(FMVSS) No. 124, Accelerator Control Systems,\2\ in two ways. First, we 
are proposing to update the throttle control disconnection test 
procedures in FMVSS No. 124. This would apply to passenger cars, 
multipurpose passenger vehicles, trucks and buses, regardless of 
weight. Second, we propose to add a new requirement for a Brake-
Throttle Override (BTO) system. The latter would be applicable to the 
same types of vehicles with 10,000 lbs. (4,536 kilograms) gross vehicle 
weight rating (GVWR) or less and that have ETC.

    \2\ 49 CFR 571.124.

    The first part of today's proposal follows up on a previous 
rulemaking effort. In 2002, NHTSA published an NPRM to update FMVSS No. 
124. That proposal was withdrawn in 2004 mainly because the agency 
concluded that further development was needed on some of the proposed 
test procedures. Today's proposal revives that effort and resolves test 
procedure issues raised in the previous rulemaking.
    The second part of our proposal, a BTO system requirement, would 
require that the brake pedal in a vehicle have

[[Page 22639]]

the capability of overriding input to the accelerator pedal when both 
are pressed at the same time. This action augments NHTSA's ongoing 
research and defect investigation efforts aimed at addressing a serious 
safety situation where a pedal becomes entrapped by a floor mat or no 
longer responds to driver release of the pedal because of some other 
obstruction or resistance.
    In general, this proposal aims to minimize the risk that loss of 
vehicle control will be caused by either: (1) Accelerator control 
system disconnections; or (2) accelerator pedal sticking and 
entrapment. For both of these safety risks, which can affect vehicles 
with mechanical as well as ETCs, the purpose of this rulemaking is to 
ensure that stopping a vehicle is possible without extraordinary driver 
actions. Accordingly, we believe both aspects of this rulemaking to 
update FMVSS No. 124 are warranted.
    For measuring return-to-idle in the event of a disconnection, this 
proposal includes updated test procedures carried over from the 2002 
proposal including a powertrain output test procedure which, under 
today's proposal, would be based on measurement of vehicle creep speed.
    For situations where the accelerator pedal fails to return after 
release, this proposal incorporates a new BTO requirement which 
     An equipment requirement to ensure the presence of BTO in 
each vehicle; and
     A performance requirement using a stopping distance 
criterion with the accelerator pedal applied.

II. Introduction

    Controlling acceleration is one of the fundamental tasks required 
for safe operation of a motor vehicle. Loss of control of vehicle 
acceleration and/or speed, so-called ``unintended acceleration'' or 
``UA'', can have serious safety consequences.\3\ It can arise either 
from driver error or for vehicle-based reasons including accelerator 
pedal interference and separation of throttle control components.

    \3\ In NHTSA's February 2011 final report ``Technical Assessment 
of Toyota Electronic Throttle Control Systems,'' the agency defined 
``Unintended Acceleration'' or ``UA'' very broadly as ``the 
occurrence of any degree of acceleration that the vehicle driver did 
not purposely cause to occur.'' Today's proposal deals mainly with a 
sub-category of UA which is characterized by accelerator pedals that 
fail to return because they are stuck or trapped.

    To address loss of control of vehicle acceleration, FMVSS No. 124 
requires an engine's throttle to return to idle when the driver stops 
pressing on the accelerator pedal or when any one component of the 
accelerator control system is disconnected or severed at a single 
point. The standard was issued under 49 U.S.C. 30111(a), which directs 
NHTSA (by delegation from the Secretary of Transportation) to prescribe 
FMVSSs. Section 30111(a) also states that ``Each standard shall be 
practicable, meet the need for motor vehicle safety, and be stated in 
objective terms.'' This subsection is also the basis for this proposal.
    In recent years, NHTSA has been working to update FMVSS No. 124 to 
more directly address newer electronic engine control systems and also 
to address different types of accelerator control safety issues such as 
those that could be mitigated by BTO technology.
    We have evaluated BTO technology to understand its performance 
characteristics and how it differs among manufacturers using this 
technology. Based on that evaluation, we believe that light-vehicle 
manufacturers in the U.S. can implement BTO on vehicles having ETC 
without significant difficulty or cost.
    Currently, there are a few vehicle models that still have 
mechanical throttle controls, and the manufacturers of those vehicles 
may lack sufficient lead time at this point and probably would incur 
significant cost to change their manufacturing plans to install BTO 
systems within the next one or two model years. This is due to the need 
to change over from mechanical throttle control to ETC for 
implementation of BTO. However, we believe in the near future these 
mechanically-throttled vehicles will be discontinued or replaced with 
new models having ETC.
    Based on compliance information that NHTSA receives from vehicle 
manufacturers annually, almost all model year 2012 light vehicles sold 
in the U.S. will have a BTO system. Based on our experience with these 
BTO systems, we believe they will comply with this proposed rule 
without significant modification. Consequently, any manufacturer 
design, validation, and implementation costs associated with this 
proposal should be minimal. Furthermore, compliance testing costs are 
expected to be low since the proposed test procedure is nearly 
identical to existing brake performance test procedures. Tests could be 
conducted along with existing brake performance tests.
    Although we do not have a statistical estimate for the number of 
fatalities or injuries that could be prevented by brake-throttle 
override technology, we believe that BTO would prevent a significant 
number of crashes and thus have a positive impact on motor vehicle 
safety. In NHTSA's complaint database, over a period of about ten years 
starting in January 2000, the agency identified thousands of reports of 
UA events of all types (see Section VIIB of this proposal). Based on 
NHTSA's review and analysis of a subset of vehicle owner-provided 
narratives in the complaints, some UA incidents appear to have involved 
stuck or trapped accelerator pedals, and a portion of those resulted in 
crashes. We believe brake-throttle override would prevent most crashes 
where a stuck or trapped accelerator pedal was to blame because, with a 
BTO system, the driver would be able to maintain control through normal 
application of the vehicle's brakes. We believe brake-throttle override 
also could prevent stuck-pedal incidents which do not result in a crash 
but which may require extraordinary driver actions to avoid a crash.

III. Safety Need for Brake-Throttle Override Systems

    One of the specific observations of the NASA in its report to NHTSA 
on Toyota unintended acceleration stated: ``When the brake can override 
the throttle command it provides a broad defense against unintended 
engine power whether caused by electronic, software, or mechanical 
failures.'' \4\ In Section A, below, we discuss actual incidents where 
a brake-throttle override system very likely would have provided a 
safety benefit. Of interest are driving emergencies in which drivers 
have extreme difficulty stopping or slowing their speeding vehicle 
because the accelerator pedal is prevented from returning to its normal 
rest position. Some of these incidents resulted in crashes and, in rare 
cases, deaths. These instances involve vehicles both with and without 
ETC systems. In Section B, we discuss how trapped pedal scenarios may 
lead to crashes. In Section C, we discuss how loss of power brake boost 
necessitates greater brake pedal pressure to stop a vehicle. Finally, 
in Section D, we discuss our conclusion that brake-throttle override 
systems can effectively prevent crashes involving trapped-pedal and 
sticking-pedal scenarios, and why we are proposing to require brake-
throttle override systems on light vehicles with ETC.

    \4\ See Observation O-2 in section 7.2, page 173, of the NASA 
report at: http://www.nhtsa.gov/PR/DOT-16-11.

A. Inability to Stop a Moving Vehicle in a Panic Situation

    On August 28, 2009, there was a passenger car crash near San Diego, 
California that resulted in the deaths of

[[Page 22640]]

four people. NHTSA's Office of Defects Investigation (ODI) inspected 
the crash site on September 3, 2009, and subsequently both ODI and the 
NHTSA Vehicle Research and Test Center inspected the vehicle. A report 
was filed on September 30, 2009.\5\ The investigators noted the 

    \5\ Memorandum from B. Collins (Investigator and Interviewer, 
Vehicle Research and Test Center) to K. DeMeter (Director, Office of 
Defects Investigation), September 30, 2009, available in the docket 
cited in the heading at the beginning of this notice.

     The vehicle was a loaned Lexus ES350 traveling at a very 
high rate of speed that failed to stop at the end of Highway 125.
     The driver was a 19-year veteran of the California Highway 
     The cause of the crash was ``very excessive speed.''
     A customer who had previously used the same loaner car 
involved in this crash reported an unwanted acceleration event, 
experiencing speeds in excess of 80 mph.
    Investigating this crash, NHTSA inspectors and the San Diego County 
Sheriff's Department discovered evidence that floor mats had trapped 
the accelerator pedal, as it was apparent that floor mats had been 
stacked in the driver footwell, the floor mat was unsecured, and the 
mat was not appropriate for the vehicle.
    The driver in this crash used the brakes during the prolonged event 
as evidenced by heat-related destruction of some brake components, but 
it is apparent that the brake application was insufficient to control 
the vehicle. It is unknown if the driver and occupants made attempts to 
use other means to stop the vehicle, including shifting the 
transmission to neutral and turning off the engine. The passenger car 
involved in the crash was equipped with a push-button keyless start 
system and a gated automatic transmission shifter with a manual shift 
mode. It did not have a BTO feature.
    NHTSA's Office of Defect Investigation has received complaints 
through the Vehicle Owner's Questionnaire (VOQ) of similar situations 
in which a driver attempted to stop a runaway vehicle. The following 
examples of this are excerpted from narrative descriptions in VOQs:

    Truck was in cruise control. Accelerated to pass slower traffic. 
Let off throttle. Truck went to full throttle. Could not get truck 
to decelerate. Had to stand on brakes to bring to a stop. Truck 
needs new rotors and pads. *The consumer stated the floor mat and 
gas pedal can interact. When the all weather mat is not clipped in 
place, and is moved under the gas pedal, it will become fully 
depressed. The mat can trap the pedal. *Updated [NHTSA-ODI 
ID 10245488]


    I was accelerating on the highway and my car continued to 
accelerate after I took my foot off the gas. I tried to brake and 
the pedal was extremely hard to press on. The car was able to slow 
down a bit but once I took foot off brake pedal the car would speed 
up again. I took my car in for service and was told they could not 
duplicate the problem and maybe a floor mat caused the problem. My 
car continues to have trouble braking. [NHTSA-ODI ID 


    While driving on a two-lane road * * * the accelerator became 
stuck. My car reached speeds of up to 80 mph. I could only reduce 
the speed to 60 mph by riding the brakes. I finally stopped the car 
by finding a safe pull-off and shifted into Neutral and then Park. 
My brakes were completely ruined and required replacement. My car 
was towed to a Toyota dealer. * * * The service department 
determined that the faulty acceleration was due to a rubber all-
weather mat. The mat had been placed over the standard floor mat. 
[NHTSA-ODI ID 10200097]

    There are similar examples of these kinds of incidents, with and 
without crashes, in complaint narratives in the VOQ database. Given our 
evaluation of brake-throttle override technology and the impact it 
could have in these types of incidents, we believe a regulation is 
necessary. Furthermore, this can be done at low cost and with minimal 
vehicle design impact. Therefore, NHTSA has decided to proceed with 
this proposal to require brake-throttle override systems.

B. How Trapped-Pedal Scenarios May Lead to Crashes

    The possibility of a trapped accelerator pedal has been widely 
acknowledged by NHTSA, vehicle manufacturers, consumer groups, and in 
the media as a key contributor to the problem of UA. Based on review of 
UA complaints in the agency's VOQ data and other sources such as media 
accounts, we can reconstruct how a pedal entrapment event might lead to 
a crash.
    Based on VOQ narratives, when a pedal entrapment occurs, it often 
follows an acceleration event such as an overtaking maneuver or a merge 
onto a highway. Upon completion of such a maneuver, when the driver 
backs off or releases the accelerator pedal, the pedal may be trapped 
due to interference caused in many cases by stacked or out-of-position 
floor mats, but it also can be caused by bunched or worn carpets or 
foreign objects in the driver footwell. In at least one case, a sharp 
edge on a plastic pedal snagged on the carpeting at wide-open throttle. 
We also have seen examples where internal friction in a pedal assembly 
prevented the accelerator pedal from springing back fully (i.e., to a 
neutral position).
    When pedal entrapment or sticking occurs, the driver is likely to 
be startled upon realizing that the vehicle is continuing to accelerate 
or is proceeding without an expected drop in speed, without any action 
on the driver's part. One possible reaction is to re-apply the 
accelerator pedal, which may dislodge it. More likely, a driver will 
attempt to apply the brakes. In doing so, a driver's conditioned 
expectation is that the brakes will produce quick and deliberate 
deceleration, responding with the same feel and feedback they provide 
in everyday driving.
    However, because the accelerator pedal is being held down and thus 
the vehicle is trying to accelerate or maintain speed, normal brake 
application usually will not result in the expected braking effect. 
This has been characterized as feeling like a ``tug-of-war'' between 
the engine and brakes. The problem is exacerbated at higher vehicle 
speeds where increased stopping effort is necessary. Also, if the 
brakes are applied with light to moderate force for an extended period, 
i.e., if the driver ``rides'' the brakes, heat-induced brake fade can 
result which lessens braking effectiveness. The loss of braking 
effectiveness may be compounded further by a reduction in brake boost, 
as described in the next section.
    From the perspective of a driver in a vehicle that is accelerating 
unexpectedly or that fails to slow down in the usual manner when the 
brake is applied, this may amount to confusing and even frightening 
vehicle behavior. Depending on the duration of the event, many drivers 
in this situation may experience panic to some degree, and their 
subsequent actions may be unpredictable.
    Especially in cases involving a high level of throttle input, in 
order to overcome the racing engine, the driver's application of the 
brakes has to be forceful and steady enough to produce a strong braking 
effect, ideally over a short duration to avoid brake fade. It is 
apparent from the complaint narratives that drivers sometimes do not 
apply steady, hard pressure to the brake pedal in these situations. 
Instead, they may ``ride'' the brakes with insufficient pedal force. Or 
they may release the brakes and repeatedly try to re-apply them, 
sometimes stabbing at the brake pedal. This kind of driver reaction is 
evident in incidents investigated by NHTSA and

[[Page 22641]]

also in complaint narratives, and it may lead to or be a result of a 
loss of power brake boost, as described below.

C. Loss of Power Brake Boost Requires Greater Brake Pedal Force

    Power brakes, as contrasted with manual brakes, provide boost to 
the brake pedal so that the force a driver must apply to the pedal in 
order to stop a vehicle is reduced. If the power assist fails, the 
brakes would still work, but the pedal force required to stop the 
vehicle would be multiplied. On vacuum-assisted power brake systems, 
which are by far the most common type in light vehicles, power assist 
is maintained by negative pressure (i.e., below atmospheric) in the 
engine's intake manifold.
    When an accelerator pedal is stuck with the throttle open, manifold 
vacuum is diminished.\6\ In order to maintain brake boost until the 
throttle closes and restores vacuum in the manifold, many light vehicle 
brake systems have to rely on residual vacuum, which usually is very 

    \6\ The degree of this diminishment depends mainly on throttle 
position and engine speed.

    If the brake pedal is pumped while the throttle is open, a loss of 
boost can ensue quickly for some vehicles. This depends on several 
factors including the rate of brake pedal application and how far the 
pedal is depressed. Brake booster volume and residual capacity are 
important factors that vary among different vehicles. Some vehicles 
have an auxiliary vacuum pump to maintain brake boost under low vacuum 
conditions, but even those systems have limitations. On vehicles with a 
hydraulic boost system, brake boost is unaffected by manifold vacuum, 
as are air brake systems in heavy vehicles. If a vehicle is equipped 
with an anti-lock brake system (ABS), engagement of the ABS provides 
brake hydraulic pressure to stop the vehicle, but sufficient brake 
pedal force still must be maintained by the driver, so having ABS does 
not always mitigate a loss of brake boost.
    Even with a loss of boost, a driver can usually bring a vehicle 
with a stuck accelerator to a stop. If a high enough brake pedal force 
is applied and held steadily, a vehicle's brakes typically are capable 
of overpowering its engine, but the force necessary on the brake pedal 
can be many times greater than that used in daily driving.
    In some of the UA complaints in the ODI database, it was reported 
that the driver eventually was able to stop a vehicle with a stuck 
accelerator by holding down the brake pedal forcefully. However, 
presumably because the required pedal pressure was much greater than 
what those drivers were accustomed to, many complainants stated that 
the brakes seemed to have failed even in cases where the vehicle was 
successfully stopped without a crash.

D. Description of Brake-Throttle Override

    A BTO is a feature that helps to address UA in trapped accelerator 
pedal situations and possibly in some other related situations. As 
reported in the press and to NHTSA, a number of vehicle manufacturers 
already have adopted brake-throttle override or will be incorporating 
BTO into their vehicle designs over the next few model years.
    Based on our technical review of the technology, brake-throttle 
override is an electronic function of the engine control system. 
Generally, it works by continuously checking the position of the brake 
and accelerator pedals and by recognizing when an acceleration command 
through the accelerator pedal is in conflict with a concurrent 
application of the brake pedal. If the BTO system identifies that a 
pedal conflict exists, it invokes the override function which causes 
the engine control system to ignore or reduce the commanded throttle 
input, thus allowing the vehicle to stop in a normal fashion. How this 
is accomplished depends on the design of the vehicle control system. In 
some vehicles, BTO engagement may partially close the throttle or 
return it to idle. In other types of powertrains, it may reduce fuel 
flow or, in the case of an electric drive system, attenuate the 
electric current driving the vehicle. Regardless of the specific means 
used, BTO intervention quickly reduces or eliminates the unintended 
vehicle propulsion.
    If a BTO system uses throttle closure to reduce power, this action 
may have the additional benefit of preventing loss of brake-boost by 
maintaining manifold vacuum (see discussion in the previous 

    \7\ Loss of brake boost is highly dependent on the type of 
vehicle propulsion and the design of its braking system.

    On a vehicle equipped with a BTO system, if for any reason an 
accelerator pedal fails to return after the driver stops pressing on 
it, BTO will engage as soon as the driver applies the brake pedal 
(there may be a delay built into the system on the order of one second; 
in some systems, other pre-conditions have to be met for the BTO to 
engage, as discussed below). By intervening in this way, the BTO system 
essentially gives the brake pedal priority over the accelerator pedal, 
allowing for normal braking. Thus, the vehicle can be brought to a stop 
with an amount of pedal effort that drivers are accustomed to, even 
though it may be clear that something out of the ordinary has occurred. 
Without a BTO system, the brakes would have to overcome the propulsive 
force of a racing engine, and the driver would have to ``fight'' the 
drivetrain as the vehicle is slowed and brought to a stop.
    Because it reduces or eliminates propulsive force and also has the 
potential to minimize loss of power brake boost, we believe that BTO 
would be very effective in scenarios like those described in the 
relevant VOQs where drivers apparently experienced trapped pedals. In 
those cases, BTO would ensure that normal application of the brake 
pedal would produce sufficient braking to stop the vehicle. This should 
minimize panic on the driver's part and very likely would lower the 
risk of a crash following a trapped pedal event.\8\

    \8\ We note that a BTO system fundamentally relies on brake 
pedal application. If the brake is not applied, even if all other 
necessary conditions are met, the BTO system will not engage and the 
vehicle accelerating force will not be suppressed. For this reason, 
pure pedal misapplication (meaning that a driver unintentionally 
steps on the accelerator pedal and does not apply the brake at all) 
is not addressed by installation of a BTO system.

    Some manufacturers' implementation of a BTO system may include 
checking for certain prerequisite conditions prior to actuation. The 
BTO system may check conditions such as vehicle speed, engine 
revolutions per minute (RPM), brake pedal travel, and pedal sequence 
(i.e., whether the brake was pressed first and then the gas pedal, or 
vice versa) to determine if the driver's intention is to stop the 
vehicle. Based on these conditions, the BTO system may determine that 
the combined brake and gas pedal inputs are actually intentional, and 
it would not necessarily intervene in that case. This may occur, for 
example, if the vehicle is at very low speed and the driver presses on 
the brake first and then on the accelerator. This behavior is 
consistent with intentional driving maneuvers which may be used for 
such things as trailer positioning or similar situations. We believe 
there is no particular safety issue in these situations, and in fact 
this type of ``two-footed'' driving capability can be desirable and may 
be in widespread use. Since there is no reason for the BTO to intervene 
in this case, today's proposal would not prohibit this kind of BTO 
design. In fact, our proposal intentionally avoids restricting the 
specific design aspects of BTO systems so that current BTO systems

[[Page 22642]]

can be accommodated to the greatest extent possible, because we believe 
those systems (based on our testing) would address the safety issue at 
    Although often caused by floor mat interference, the failure of an 
accelerator pedal to return after release may also result from ``sticky 
pedal'' situations.\9\ Depending on the source of ``stickiness'' in an 
accelerator pedal, we believe that brake-throttle override will be an 
effective countermeasure in most instances as it would treat sticky 
pedals the same as trapped pedals, and thus would prevent any 
significant vehicle acceleration once the brake pedal is applied.

    \9\ This may occur due to a malfunction in the moving parts of 
an accelerator pedal assembly causing the pedal to lose its ability 
to quickly spring back to its rest position. The assembly, after it 
has been in service, may develop excessive internal friction for a 
variety of possible reasons such as: internal springs or sensing 
elements can break; seating surfaces and housings can deform or 
fracture and fragments may lodge in moving parts; or foreign liquids 
can penetrate and coagulate inside the assembly. Manufacturing 
variation can play a role, as well as environmental factors like 
heat, cold, and moisture, which can lead to warping and corrosion. 
NHTSA has experience with pedal defects of this kind which have led 
to recalls, most notably the Jan. 2010 recall of accelerator pedal 
assemblies in Toyota vehicles [NHTSA Recall no. 10V-017].

    We note that an ETC system may recognize when a pedal assembly is 
malfunctioning, and it may be able to invoke some fail-safe action 
without involving BTO. This would depend on the nature of the 
malfunction and the design of the control system. For example, an ETC 
could override the accelerator pedal assembly if signals from the pedal 
position sensor exceed design limits. This could occur without brake 
pedal application. This is a desirable response to a broken pedal 
assembly and meets the need for safety independent of any brake-
throttle override capability.

IV. Technical Discussion of Accelerator Control System Safety Issues

A. Accelerator Control System Disconnections

    In the past, vehicles had mechanical throttle systems consisting of 
rods, levers, cables, and springs to translate movement of the driver-
operated accelerator pedal into throttle plate rotation. These systems 
were subject to the possibility of disconnection or separation of its 
linkages. Without a safety countermeasure such as a spring-loaded 
throttle plate, a disconnection in a mechanical system could result in 
a throttle plate that remained open after the driver let off of the 
accelerator pedal.
    Similarly, return springs are susceptible to the possibility of 
disconnection or breakage, which could lead to an open throttle if the 
control system lacks a backup spring or other supplemental means of 
closing the throttle.
    There also is the possibility that an accelerator control system 
could have excessive friction between its moving parts, especially in 
very cold temperatures. This could inhibit the throttle from 
immediately rotating back to idle after release of the accelerator 
    FMVSS No. 124 has been in place since the 1970s to ensure that 
disconnections, separations, or severances do not result in an open 
throttle and potentially a runaway vehicle. The Standard also prohibits 
ACSs that return the throttle to idle too slowly even with no 
disconnections, which could be hazardous in severe instances.
    These protections against disconnections and slow-returning 
throttles are carried forward in today's proposal.

B. Electronic Throttle Control

    Now that mechanical accelerator controls have been superseded by 
ETC, the kinds of failures that might occur are somewhat different. In 
an ETC or ``throttle-by-wire'' system, the driver still uses an 
accelerator pedal to modulate drivetrain output. However, most of the 
mechanical components linking the pedal to the throttle on the engine 
now are supplanted by electronic components including sensors, electric 
motors, a control module, and connecting wires. Some mechanical parts, 
particularly springs, are still employed, but the primary connection 
between the pedal and the engine throttle is electronic.
    Disconnections of the kind covered by FMVSS No. 124 are possible in 
ETC systems, but would involve separation of electrical connectors or 
severance of connecting wires rather than disconnection of linkages or 
cables. In official letters of interpretation, NHTSA has asserted that 
disconnection of power and ground wires in ETC systems, as well as 
shorting of those wires, are to be considered among the faults covered 
by the Standard, and the agency has conducted compliance testing 
accordingly. However, none of these electrical disconnections are 
explicitly addressed in FMVSS No. 124 currently.\10\ As such, today's 
proposal updates FMVSS No. 124 to incorporate these interpretations so 
that the standard will now have specific regulatory language to address 
electronic ACSs.

    \10\ For a fuller discussion of these letters of interpretation, 
please see NPRM of July 23, 2002 (67 FR 48117).

C. Potential ETC Failures Not Covered

    ETC systems generally are designed with fail-safe characteristics 
such as fault checking and control redundancy to prevent throttles from 
opening unintentionally. They often have ``limp home'' modes which 
restrict the throttle opening to a small range when a fault occurs. 
These fail-safe characteristics limit engine power so that the vehicle 
is incapable of abrupt acceleration. However, NHTSA understands that 
manufacturers and suppliers have implemented ETC systems in different 
ways and have incorporated different fail-safe characteristics in the 
design of these systems.
    Allegations of throttles failing to close after accelerator pedal 
release, or throttles opening unexpectedly without accelerator pedal 
input, have been widely publicized, and it has been alleged that some 
such incidents have been caused by electronic faults such as errant 
throttle control signals or ambient electrical disturbances. The agency 
has been carefully evaluating the safety of ETC systems through 
research and defect analysis, and we engaged the National Academy of 
Sciences (NAS), an independent scientific body, to study the problem of 
UA in motor vehicles. The NAS issued a report in January 2012 to 
broadly address the issue of safety in electronic vehicle control 
systems. (Note that this study is different from the NASA report 
released in February 2011 which focused specifically on Toyota ETC 
systems.) \11\

    \11\ The NASA report is available at: http://www.nhtsa.gov/PR/DOT-16-11. After ten months of studying Toyota's ETC system, NASA 
was not able to identify an electronic cause of large, unintended 
throttle openings.

    Until this work is complete, it is premature to propose additional 
safety requirements at this time. Therefore, the only ETC failures 
within the scope of this proposal are disconnections of ETC components 
and wiring which result in open or short circuits, which is consistent 
with NHTSA interpretations of the current language of FMVSS No. 124.

V. Proposed Update of FMVSS No. 124 Test Procedures

    We believe that changes set forth in this proposal are necessary to 
ensure that the longstanding requirements in FMVSS No. 124 remain 
relevant for modern ACSs.

[[Page 22643]]

    Although this proposal introduces new test procedures, we believe 
it does not impose a significant new burden on vehicle manufacturers. 
In fact, we expect it can relieve certification burden by providing 
test procedures for different kinds of accelerator control systems and 
also by accommodating fail-safe strategies other than return of a 
throttle to a mechanical stop.
    We note that this portion of today's proposal is nearly the same as 
the 2002 NPRM (July 23, 2002, 67 FR 48117), with two exceptions. First, 
an intake airflow rate criterion has been added to the other 
disconnection test procedures as a compliance option that may be useful 
for spark ignition engines. This criterion has been added in response 
to comments on the 2002 NPRM. Secondly, the powertrain output test we 
are proposing would use vehicle terminal speed or ``creep speed'' 
instead of some other parameter like engine speed or torque. This also 
has been added in response to comments on the 2002 NPRM.

A. Purpose and Scope of FMVSS No. 124 at Present

    The scope of FMVSS No. 124 as it currently exists is limited to how 
quickly a throttle returns to idle, either in normal operation (i.e., 
without any disconnections) or in the event of a disconnection or 
severance in the control system. We have sought to maintain the scope 
of the existing Standard by limiting today's proposal to what was 
designated in past agency interpretations as being within scope, and by 
limiting the additional test procedures to the minimum necessary for 
non-mechanical ACSs. For example, where the present Standard applies to 
single-point failures such as the disconnection of one end of a 
throttle cable, today's proposal also is limited to single-point 
disconnections such as removal of a single electrical connector or 
severing a conductor at one location.
    The current language of the test procedure in FMVSS No. 124 is 
expressed in terms of the return of an observable moving part, i.e., 
the throttle plate, to a closed or nearly closed position. It does not 
prescribe other types of vehicle fail-safe responses besides throttle 
closure. This neglects the variety of ways in which powertrain output 
in a vehicle with a modern throttle control system can be reduced to an 
acceptably benign level, e.g., spark adjustment, even though the 
throttle plate may be at a non-idle position. It also leads to non-
optimal test procedures for hybrid or electric vehicles and diesel-
engine vehicles whose drive power may not be governed by throttle 
    The current Standard's stated purpose is to ``prevent engine over-
speed.'' The sole performance criterion, expressed in terms of throttle 
plate closure, does indeed have the effect of limiting engine speed, or 
more specifically engine torque. That, in turn, limits power output to 
the drive wheels.
    FMVSS 124's focus on control of the throttle was a convenient 
criterion at the time the Standard was adopted. However, NHTSA does not 
believe the intent of the Standard should be construed as merely 
setting a limitation on throttle position. Instead, it is evident that 
the fundamental safety purpose of the Standard is to prevent a 
vehicle's powertrain from creating excessive driving force when there 
is no input to the accelerator pedal. There would be no safety reason 
whatsoever to require the throttle to close if that did not limit 
vehicle propulsion.

B. Need for Update of FMVSS No. 124

    Even if it is well established that FMVSS 124 does apply to ETC 
systems, regulating ETC systems by drawing analogies to mechanical 
systems has undesirable outcomes. This can lead to situations, as we 
have mentioned, where safe engine responses are discounted, and test 
methods for some alternative types of vehicle propulsion are not 
clearly defined.
    There are important questions about exactly how the Standard should 
be applied to ETC. For example, in a request for interpretation, one 
vehicle manufacturer suggested that merely placing two return springs 
on the accelerator pedal assembly satisfied the requirement for ``two 
sources of energy'' capable of returning the throttle to idle. NHTSA 
responded that, while that approach might be enough to satisfy the need 
for pedal return, it could not ensure return of the engine throttle 
itself in the event of a disconnection beyond the pedal.
    Another reason that FMVSS 124 needs updating is that powertrain 
responses that can result from failures in electronic systems are much 
more varied than with mechanical systems. Fuel injection and ignition 
timing are among factors that can be varied without any change in 
throttle position.
    For example, we have seen engines with spring-loaded throttles that 
do not close fully to idle when disconnected from the electrical 
harness. They assume a default position that is slightly more open than 
idle. This kind of ``limp-home'' feature presents no safety hazard. In 
fact, it provides a safety benefit by avoiding engine stalling and 
allowing the vehicle to be moved out of traffic, which can be critical 
for preventing a crash. Engines with this kind of design may accomplish 
the essential fail-safe performance by retarding the ignition timing or 
restricting fuel delivery so that the engine torque output is limited 
to a level at or below what is normally provided at idle. A design of 
this kind thus is able to achieve an equivalent level of safety without 
full return of the throttle.
    Other technology also illustrates the need for this update of FMVSS 
124. Modern engines routinely have variable valve lift and/or timing 
control. In at least one recent engine design, the level of valve 
control is great enough that the throttle plate no longer throttles the 
engine during at least part of the engine's operating range. Instead, 
air intake is throttled to a large extent by the intake valves 
themselves while the throttle plate stays in an open position. In such 
a design, requiring ``return of the throttle to the idle position'' 
would be design restrictive without any safety justification.
    Furthermore, the reduced relevancy of the throttle plate removes 
the most easily observable component for verifying return-to-idle. For 
some engines such as electronically controlled diesel engines with 
unitized injectors, assessing compliance cannot be done by simply 
observing retraction of a traditional fuel rack to a set position. This 
means that some alternative method of verifying return-to-idle is 
    In spite of these facts, even the most advanced engines do have an 
idle state, and it is still possible to identify a measurement 
criterion for them and to expect these types of engines to return to a 
safe idle state.
    In order to recognize the advancement of engine technology, and to 
better regulate advanced vehicle propulsion systems, improved 
regulatory language is needed. This proposal addresses this need with 
revised regulatory language to include new test procedures that can be 
applied to a variety of vehicle propulsion systems.

C. Applicability to Electronic Throttle Control Components

    NHTSA concluded in published interpretation letters that electrical 
wires and connectors in an electronic ACS are analogous to mechanical 
components in a traditional ACS and are therefore subject to the same 
safety requirements as their mechanical counterparts. We were able to 
conclude this because the regulatory language, although modeled on 

[[Page 22644]]

features of carbureted engines, actually is stated in very general 
terms. It defines the ACS as ``all vehicle components, except the fuel-
metering device, that regulate engine speed in direct response to the 
movement of the driver-operated control and that return the throttle to 
the idle position upon release of the actuating force.''
    NHTSA stated that the ACS does not consist only of the accelerator 
pedal assembly and the wiring harness connecting it to the engine 
control module (ECM), but extends beyond the ECM to include connections 
to the actual throttling device on the engine. We stated that the ACS 
must extend beyond the pedal assembly because those components are the 
only link between the engine throttle and the accelerator pedal. 
Otherwise, if the electrical connection between the ECM and throttle 
actuator was disconnected for example, no fail-safe action would be 
required, which would be contrary to the Standard's primary purpose.
    There was also the issue of whether the ECM itself should be 
considered part of the ACS. We concluded in the interpretation letters 
that the ECM should be considered an ACS component for the purposes of 
the Standard because throttle control signals originate within it. We 
stated that the ECM as a whole unit, along with its associated external 
connective wires, are critical ``linkages'' that in effect form a 
connection from the gas pedal to the engine throttling device.
    On the other hand, it was less clear whether internal circuitry 
within the ECM or another enclosed electronic module should be subject 
to ``severances and disconnections.'' If that were the case, the system 
might have to withstand disruption of internal electronic elements such 
as the microprocessor without causing loss of throttle control. 
Instead, we concluded that the internal elements of an ECM, besides 
serving functions unrelated to throttle control, are analogous to the 
internal fuel-metering parts of a carburetor, which the existing 
Standard's ACS definition specifically excludes. Thus, the agency's 
position has been that severances or disconnections of elements inside 
of the ECM or another enclosed module in the ACS are outside the scope 
of Standard No. 124.
    The 2002 proposal included new regulatory language to clarify FMVSS 
124's applicability to electronic components. It included the following 
requirement for fail-safe performance:

    Severances and disconnections include those which can occur in 
the external connections of an electronic control module to other 
components of the accelerator control system and exclude those which 
can occur internally in an electronic control module.

The interpretation letters (discussed in the July 2002 NPRM) also 
recognized that disconnections of wires between electronic components 
could result in short circuits, not just open circuits. For that 
reason, the proposed regulation also stated:

    The accelerator control system shall meet [these] requirements * 
* * when either open circuits or short circuits to ground result 
from disconnections and severances of electrical wires and 

These requirements are carried forward in today's proposal.

D. Test Procedures of the 2002 NPRM

    Of the several test procedures included in the 2002 NPRM, the first 
was essentially the air throttle plate position of the original 
Standard, normally applicable to conventional gasoline engines.
    A second proposed procedure, new to FMVSS 124, allowed for 
measurement of net fuel flow rate, and was included primarily for 
diesel engines, but could be applied to vehicles with other types of 
    A third proposed procedure, also new, allowed for measurement of 
electric current flow to an electric drive motor, and was intended for 
electric vehicles and for the electric driven portion of hybrid 
    Finally, the 2002 NPRM proposed a new procedure which would use 
engine speed to indicate idle state. As conceived, the procedure was to 
be conducted on a chassis dynamometer in order to simulate a realistic 
load on the drivetrain. RPM was thought to be a valid idle-state 
measurement as long as the appropriate amount of load was exerted on 
the drivetrain of the vehicle so that the engine speed response 
reflected actual driving conditions. The engine RPM test was considered 
a multi-purpose test because it could be applied to different 
powertrain types including those of gasoline, diesel, and possibly 
electric vehicles.
    Under the 2002 NPRM, a manufacturer could choose any one of the 
proposed test procedures as a basis for compliance, and the choice was 
to be irrevocable so that failure to comply under the selected 
procedure could not be negated merely by trying each of the other 
procedures in hopes of successfully complying.
    All of the procedures in the proposal were premised on return to a 
``baseline'' idle condition which was the measured idle of the vehicle 
in normal operation, i.e., without any faults or disconnections in the 
ACS. Return to the ``baseline'' idle was treated as analogous to return 
of a throttle plate to the idle position. A tolerance was deemed 
appropriate to accommodate overshoot and/or fluctuation which are 
possible responses when disconnections are present in electronically 
controlled throttle systems. The proposal set the idle state tolerance 
at 50 percent above the measured baseline value.

E. Powertrain Output Test Procedures and ``Creep Speed''

    Early on in the effort to update FMVSS No. 124, comments from 
industry groups led to the idea that a performance test which measured 
engine output would be a useful alternative to a throttle position 
test. Among suggested measurement criteria were engine RPM and drive 
wheel torque. This idea evolved into using vehicle speed as a 
measurement criterion, and the term ``creep speed'' was applied to this 
because it would measure the speed that a vehicle has when it 
``creeps'' along. Creep speed describes the condition of a vehicle 
moving under its own power when it is in gear and has no input to the 
driver-operated accelerator control. It is defined as the maximum or 
terminal speed that a vehicle can achieve in that condition both with 
its ACS intact and with disconnections.
    This test had the significant advantage of being ``technology-
neutral'' meaning that it would be applicable to all forms of vehicle 
propulsion. However, measuring vehicle speed as a compliance criterion 
necessitates testing a vehicle under real or simulated driving 
conditions. That meant that a chassis dynamometer would be required for 
a creep speed test, or else the vehicle would have to be tested on a 
test track.
    At the time of the 2002 proposal, NHTSA was persuaded that the 
creep speed test had merit, but decided that further evaluation of the 
idea was necessary for a number of reasons. First, it was necessary to 
verify feasibility of using a dynamometer to measure creep speed since 
the agency did not have a similar procedure in any other regulation. 
Second, it would be necessary to determine whether creep speed was a 
useful and practical performance criterion. Lastly, we wanted to 
demonstrate the practicability of conducting compliance tests using 
that approach.
    Subsequent to the 2002 NPRM, NHTSA conducted a series of tests 
using a wheel-driven (chassis) dynamometer at the Transportation 
Research Center (TRC) in East Liberty, Ohio. A report

[[Page 22645]]

describing the testing and results is available in the docket number 
cited in the heading of this notice. Tests were conducted using three 
ETC-equipped vehicles instrumented with torque wheels on their drive 
axles for measurement of the net acceleration or deceleration torque. 
As described in the report, the dynamometer was programmed so that its 
power absorption simulated the net road force of actual driving 
conditions, including the effects of tire rolling resistance and 
aerodynamic drag unique to each test vehicle.\12\

    \12\ Road force data is available for U.S. vehicles through the 
Environmental Protection Agency's annual vehicle database which is 
available on the EPA Web site: http://www.epa.gov/otaq/crttst.htm. 
The EPA measurements are derived using a coastdown technique defined 
in SAE J2264 ``Chassis Dynamometer Simulation of Road Load Using 
Coast Down Techniques'' (APRIL 1995).

    Dynamometer tests were conducted on each vehicle in a variety of 
operational conditions including both normal operation and with 
disconnection faults. The testing evaluated vehicle response to the 
types of disconnections that are possible in electronic ACS systems. 
Torque output, vehicle speed, and engine RPM were measured parameters 
of each test. Throttle plate position was also monitored. The latter 
was useful for determining if a vehicle's design strategy to limit 
engine power during fail-safe operation was to use throttle control or 
some other factor. The following are key test results of NHTSA's 

                                          ACS Creep Speed Test Results
                                          Chevrolet pick-up,     Buick Lacrosse sedan,    Toyota Corolla sedan,
                                             LT245/75R16               P225/55R17               P195/65R15
Creep Speed at unfaulted idle........  3 mph-4 mph............  5 mph..................  4.9 mph.
Maximum faulted creep speed..........  9 mph..................  23.5 mph...............  23.6 mph.
Fault condition where maximum creep    Disconnection at         Pedal harness            Disconnection at
 speed occurs.                          throttle actuator        disconnect at 40 mph     throttle actuator
                                        (whole connector).       or greater.              (whole connector).

    This NHTSA testing indicated that drivetrain torque values were low 
following each sampled type of ACS disconnection. This was evident in 
that the test vehicles' engines did not race to a high RPM level and 
the vehicles decelerated or gradually accelerated (depending on the 
initial test speed) to their terminal creep speeds. The vehicles 
behaved as if they were operating either in a normal idle or a ``high 
idle'' condition, except in a few cases where the result was stalling 
or rough idling. The vehicles remained easily controllable in terms of 
being free of any abrupt acceleration. At any point in each test, it 
was possible to bring the test vehicles to a stop on the dynamometer 
with only light brake application (equivalent to or only marginally 
greater than that needed to prevent movement of an in-gear vehicle at a 
normal idle).
    The drivetrain output test procedure that we are proposing today as 
an alternative to throttle position, fuel delivery rate, air intake 
rate, or electric power delivery is based on this creep speed 
methodology. We are proposing that FMVSS No. 124 should allow a maximum 
creep speed for all vehicles of 50 km/h (31 mph). This is a speed that 
we concluded would accommodate typical light vehicle responses to ACS 
disconnections including various limp-home modes. This was based in 
part on a demonstration of vehicle response to pedal position sensor 
disconnection using a popular passenger vehicle with ETC. The 
demonstration was conducted as part of an ex-parte meeting and 
discussion with vehicle manufacturers as a follow-on to the 2002 

    \13\ See docket NHTSA-2002-12845-0014, record of discussion and 
demonstration held on December 10, 2002, with Toyota.

    Our subsequent laboratory tests, as reported above, showed that 
this level of speed is equivalent to a relatively small amount of 
drivetrain torque output. Considering that this speed would be the 
ultimate terminal speed of a vehicle with an ACS disconnection, it 
represents a small and easily controllable amount of vehicle 
acceleration. We believe that it is a reasonable threshold that would 
ensure safety in the event of an ACS disconnection.
    The proposed procedure would measure terminal speed following an 
ACS disconnection from any initial vehicle speed. It is divided into 
two parts, corresponding to whether the initial test speed is greater 
or less than the required maximum of 50 km/h. For initial speeds lower 
than 50 km/h, the vehicle's terminal speed following an ACS 
disconnection would have to stay below the 50 km/h threshold. For 
higher initial speeds, the terminal speed following a disconnection 
would have to drop to 50 km/h or lower within some specified period of 
time after the accelerator control is released. We call the latter case 
the ``coastdown'' procedure. The creep speed and coastdown procedures 
are discussed in more detail later in this document.

F. Comments on the 2002 NPRM

    A number of comments were submitted in response to NHTSA's 2002 
NPRM (before it was withdrawn). Commenters included The Alliance of 
Automobile Manufacturers (Alliance), The American Trucking Associations 
(ATA), The Association of International Automobile Manufacturers 
(AIAM), and The Truck Manufacturers Association (TMA). Some individual 
member companies of those organizations also submitted comments 
including Blue Bird Body Company, BMW Group, Ford Motor Company, 
American Honda Motor Company, and Volkswagen of America, Inc.
    The comments were generally supportive of NHTSA's effort to update 
FMVSS 124, but raised a number of important issues. To a great extent, 
changes we have made in the current proposal vis-[agrave]-vis the 2002 
NPRM address those issues. The following is a brief point-by-point 
summary of the comments:
     Cancellation of ``limp-off-the-road'' mode by brake pedal 
application is design restrictive.
     50 percent idle state tolerance is insufficient and could 
lead to stalling; range should be defined by manufacturer or some 
different way.\14\

    \14\ AIAM did not suggest a specific definition.

     Favors having compliance options, but objects to 
``irrevocable selection.''
     Suggests fuel delivery and air intake rate tests be done 
simultaneously (combine S6.2 and 6.3), i.e., measure both quantities at 
once; vehicle ``passes'' if either measurement meets the specification.
     Recommends allowing optional early compliance with the new 

[[Page 22646]]

     Favors deleting ``normal operation'' requirement or at 
least adding appropriate test procedures.
     Increase delay time allowed for return of entire 
powertrain to idle state in the proposed RPM test.
     Allow manufacturer to define an acceptable range for idle.
     If NHTSA keeps tolerance, 50 percent is not large enough.
     Procedure in S6.2.5, S6.3.5, and S6.5.5 should say 
``remove actuating force after at least 3 sec. but before X sec.''
     Concerned with use of ``indefinitely'' with respect to 
maintaining idle following disconnection.
     The dynamometer-based RPM test procedure would be overly 
burdensome because manufacturers would have to consider so many 
permutations of vehicle mass, final drive gearing, and drag.
     Uncertainty in measurement of RPM return time by itself is 
probably greater than the specified 3 second allowance.
     Tolerance of 50 percent is too small--high altitude 
example given; suggests much larger tolerance since even twice the 
baseline (100 percent tolerance) would still be safe for drivers to 
     With automatic transmissions, gear selection is modified 
after an ETC failure occurs, i.e., the vehicle cannot maintain same 
gears in failure-mode tests as in baseline tests.
     Favors measuring vehicle speed, not engine speed, in RPM 
     Favors establishing an overall powertrain output test as 
main criterion in the safety standard.
     Maximum idle should be defined according to manufacturer, 
not according to baseline measurement.
Blue Bird
     Supports the 2002 NPRM in full; two year lead-time 
relieves burden of compliance.
     Supports NHTSA effort; specific comments included with 
Alliance and TMA submittals.
     Recommends that the ``idle state'' definition be 
consistent throughout the standard.
     Recommends performance-based test for cancellation of 
``limp-home'' mode instead of specifying brake application which is too 
design restrictive.
     Believes that the 50 percent tolerance should be adjusted 
to account for likely variation in fuel rate at or near idle.
     Believes tolerance concept is impracticable and 50 percent 
is inadequate.
     linking maximum idle to baseline is design restrictive and 
unnecessary for safety.
     Fail-safe idle state varies too much to achieve stable 
conditions for comparison to baseline.
     Stalling will result if fail-safe idle is restricted as 
     Standard 124 should be based on a manufacturer-specified 
maximum idle.
     Suggests technology neutral ``powertrain torque output'' 
test for fail-safe operation.
     Technology-neutral test should apply to normal operation 
as well as fail-safe (but not sure what compliance criterion should be 
     Return to idle should not be required before removal of 
pedal force after fault inducement.
     Asks for confirmation that manufacturers will be allowed 
to make running changes in production to ``irrevocable selection''.
     Electronic ``dashpots'' should be treated the same as 
mechanical ones in current standard (however, this would be unnecessary 
if NHTSA allows manufacturer-specified maximum idle).
     ``Detection by powertrain control system'' should be added 
to stop-lamp illumination as an allowable indicant of brake pedal 
     When air throttle percent-opening is close to zero at 
idle, 50 percent is meaningless.
     Definition of ``air throttle position'' neglects non-
rotating (slide type) throttles; suggests a simplified definition.
     Anticipates most trucks using fuel rate test to comply; 
suggests that fuel rate signal, not fuel delivery rate, is the 
appropriate criterion.
     Severing power to the ECM shuts down processor, which 
means fuel rate signal goes away, which would necessitate observing 
some other compliance measure.
     Wants to allow bench test of stand-alone engine instead of 
whole vehicle but not sure how ``impose test load'' as used in the 
procedures would apply to a test of a stand-alone engine, i.e., not 
mounted in a truck chassis.
     Irrevocable selection wording too restrictive.
     Recommends performance-based specification for removal of 
limp-home mode, not the design-restrictive ``service brake apply'' in 
the NHTSA proposal.
     Wants return to or below the baseline to be an acceptable 
     Asks if the tolerance is based on 50 percent of the 
average, maximum, minimum, or what? Also thinks the term 
``indefinitely'' should be defined or quantified.
    Generally, these comments have been addressed in today's proposal 
where appropriate or necessary. We have removed the procedure which 
specified that a limp-home mode would have to be cancelled by a light 
application of the service brake. Limp-home modes instead have to fall 
within the 50 percent tolerance of the applicable idle state indicant, 
or cannot exceed the allowable creep speed of 50 km/h.
    We have not increased the tolerance but left it at 50 percent as 
proposed in 2002 because commenters did not provide a specific 
alternative value or any rationale to support changing the tolerance.
    We have maintained the ``irrevocable selection'' stipulation given 
that we want to deter a manufacturer that fails to comply under their 
chosen test option from claiming compliance under another test option.
    In regard to determining the idle state for a test vehicle, we 
continue to believe that measuring a baseline value for the idle prior 
to executing any disconnections is a better alternative than requiring 
the vehicle manufacturer to provide idle state information for each 
test vehicle. This issue was discussed in the 2002 NPRM, and the 
reasoning has not changed. Essentially, we believe it is more expedient 
and practical to ascertain the baseline idle as part of the test 
    Among other issues raised in comments on the 2002 proposal, and how 
we propose to address them, are the following:
     We have elected to leave FMVSS No. 124's ``normal 
operation'' requirement in today's proposal because it has always been 
part of the Standard and no compelling reason for removing it was 
offered by any commenter. It may be relevant for vehicle operation in 
very cold temperatures.
     Some commenters disagreed with our use of ``indefinitely'' 
to refer to the required duration of a vehicle's return-to-idle 
following a disconnection. We believe it is necessary for safety to 
prohibit a design in which the throttle initially responds to an ACS 
disconnection by closing but re-opens

[[Page 22647]]

after a short time. We would consider alternative suggestions for how 
to ensure that idle is maintained following disconnection, and we 
request comment on this issue.
     The tolerance of 50 percent may not be relevant when 
applied to a throttle position because it is not valid for a closed or 
nearly closed throttle. In general, engine output is not a linear 
function of ``percent throttle opening.'' NHTSA requests comment on the 
best way to evaluate throttle position as it relates to engine output 
(i.e., angular position, percent of full open, or some other measure) 
and how the 50 percent tolerance should be applied to throttle 
     Regarding the comment suggesting how to define throttle 
position for rotating air throttles, we note that the term ``percent 
throttle opening'' was not defined in the 2002 proposal even though it 
was used in one of the proposed compliance criteria. As above, we are 
requesting comment on how best to define throttle position so that it 
corresponds with drivetrain output.
     Regarding the comment that, when measuring fuel rate or 
air intake rate, disconnection of the ECM power might cause the 
internal processor to stop functioning, and thus the fuel rate or air 
intake rate signal would cease: We do not view this as a significant 
difficulty because it can be assumed that the engine would shut down in 
this case, which would of course qualify as a complying vehicle 
response since powertrain output would go to zero.
     To the extent that we have not addressed in today's 
proposal comments that were made on the 2002 NPRM and remain relevant, 
we request further comment in response to this proposal.

VI. Notice of Proposed Rulemaking

    This section explains how we propose to amend FMVSS No. 124 so that 
crashes and associated injuries or deaths as described previously can 
be minimized.
    Based in part on NHTSA's VOQ data, we propose in this NPRM to 
address drivers' inability to stop vehicles in stuck-accelerator 
emergencies by amending FMVSS No. 124 to require a brake-throttle 
override system on all light vehicles having ETC.
    With this requirement, we intend for the effect of the BTO system 
to be independent of the stopping capability provided by a vehicle's 
service brakes. That is, even if stopping power alone is sufficient for 
a vehicle to meet the performance requirement under high-speed, open-
throttle conditions, we are proposing that there still must be 
electronic intervention invoked by brake application to abate drive 
torque caused by a stuck accelerator pedal.

A. Definition of Electronic Throttle Control System

    We propose to define electronic throttle control as an accelerator 
control system in which movement of a driver-operated control is 
translated into throttle actuation at least in part by electronic, 
instead of mechanical, means. Note that in this definition, 
``accelerator control system,'' ``driver-operated accelerator 
control,'' and ``throttle'' are separately defined terms whose 
definitions are included in the regulatory text. This definition is 
necessary to identify vehicles to which the BTO requirements would 
apply, i.e., those having ETC.

B. Brake-Throttle Override Equipment Requirement

    We also are proposing an equipment requirement for BTO. This would 
be included in addition to a BTO performance requirement as described 
in the next section. We are proposing the requirement in paragraph 
S5.4.1 of Sec.  571.124.
    The equipment requirement also would specify that a BTO system may 
be designed so that it does not engage at speeds below 10 mph, as 
discussed below.
    This equipment requirement is necessary to ensure that a brake-
throttle override capability is installed on each vehicle, and that a 
manufacturer's certification is not based only on brake system 
performance. Otherwise, it might be possible for a manufacturer whose 
vehicle meets the BTO performance test without engagement of a BTO 
system to avoid installing BTO altogether.\15\ Under this requirement, 
BTO must engage if the powertrain controller determines that inputs to 
the brake and accelerator pedals are conflicting. This means not just 
that the pedal inputs are overlapping but also that they probably are 
unintentional; are unlikely to occur in normal driving; and may create 
an unsafe operating condition. For example, if a vehicle is travelling 
at a high rate of speed, and the brake is forcefully applied while 
accelerator pedal input signal remains high, it is logical to conclude 
that the driver's intent is to slow the vehicle and that the throttle 
command should be ignored. On the other hand, if overlap between the 
accelerator pedal and brake exists only briefly, such as for less than 
one second, there is no reason to engage an override feature since a 
vehicle could not accelerate much in such a short time span, and the 
potential for loss of control would be very small.

    \15\ This approach of combining an equipment requirement with a 
performance test is similar to the approach NHTSA used in 
establishing FMVSS No. 126, ``Electronic Stability Control 
Systems.'' In that rulemaking, NHTSA stated, ``An equipment 
requirement is necessary because it would be almost impossible to 
devise a single performance test that could not be met through some 
action by the manufacturer other than providing an ESC system.'' 
[72FR17238]. In the case of brake-throttle override, whereas the 
proposed performance test is based on stopping distance requirements 
in FMVSS No. 135 which many vehicles can meet with a significant 
margin, it is likely that some vehicles, for instance those with 
high brake-torque-to-drive-torque ratios, could meet the proposed 
BTO performance test without actually having a BTO system.

    This proposed equipment requirement makes BTO engagement optional 
below 16 km/h (10 mph). We believe this will accommodate most ``two-
footed'' driving situations which have legitimate purposes such as 
maneuvering trailers, pushing other vehicles (as police sometimes do to 
move stalled vehicles out of traffic), and in off-road driving. These 
driving scenarios are not considered to be unsafe, and there is no 
compelling safety reason to prohibit them.
    The proposed equipment requirement limits required BTO engagement 
to ``conflicts'' between the accelerator pedal and brake, so that BTO 
systems can allow for left-foot braking and other two-footed driving 
situations as manufacturers see fit to accommodate their customers. For 
example, a brake-first-then-accelerator sequence of pedal application 
would not necessarily be considered a ``conflict'' and so would not 
always have to engage the BTO.
    The 10 mph (16 km/h) cut-off is the speed below which initial 
engagement of BTO is not required. That is, if a pedal conflict 
initially occurs below 10 mph, the onset of BTO intervention is not 
required until the vehicle speed reaches 10 mph. Once vehicle speed 
reaches 10 mph, BTO must engage at that point, assuming other 
conditions for engagement exist. This does not mean that, if BTO 
engages at a speed above 10 mph, the BTO can disengage as the vehicle 
slows to below 10 mph. It must remain engaged until the vehicle has 
been brought to a stop and remain engaged until either the pedal 
conflict no longer exists (for example, if the driver releases the 
brake, or the gas pedal becomes unstuck), or vehicle drive power is 
removed by another action such as turning off the ignition.
    We have considered whether it is appropriate to require that BTO 
activation be accompanied by a warning or alert to signal to the driver 
that BTO intervention has occurred. This could be in the form of either 
a visible or audible alert. We are not proposing that such an

[[Page 22648]]

alert be required, but we request comment on this issue, specifically 
if there is any safety data that would justify such a requirement.
    A related issue is whether it should be possible for a vehicle 
operator to manually turn off the BTO function. For example, a switch 
or control could be provided for that purpose, similar to on/off 
switches for disabling Electronic Stability Control (ESC). 
Alternatively, a manufacturer might design an ``ESC off'' switch so 
that it also disables the BTO. We are not proposing to prohibit 
controls that turn off BTO. However, if a vehicle is equipped with a 
control for turning off BTO, we believe that the driver should be 
warned that the system is off, and the system should always default to 
a ``BTO On'' state whenever the ignition is cycled. We request comment 
on whether a BTO Off function should be allowed and, if so, how it 
should function.

C. Brake-Throttle Override Performance Requirement

    As indicated previously, we are taking the approach in this 
proposal of including both a performance requirement and an equipment 
requirement for brake-throttle override systems. We considered 
establishing a design requirement as the sole requirement for BTO, but 
the differences among BTO systems currently available from different 
vehicle manufacturers are significant enough that a design requirement 
by itself cannot effectively accommodate them all without being overly 
complex and/or design restrictive. By combining a relatively simple 
performance test with the basic equipment requirement described above, 
we can achieve a robust standard which is largely performance-based and 
minimally costly or burdensome.
    We believe this approach is appropriate because, by all 
indications, existing BTO systems are effective for their intended 
purpose, and we would not be able to justify a BTO requirement that 
favors one design over another or compels some manufacturers to go to 
the expense of re-designing their systems. In fact, NHTSA recently 
sampled a number of current BTO systems in a brief series of high-
speed, open-throttle braking tests.\16\ Those tests demonstrated that 
each of the different BTO designs was very effective. In each test, at 
speeds up to 99 mph, stopping distances of BTO-equipped vehicles with 
their accelerator pedal held to the floor typically were less than 5 
percent to no more than 15 percent greater than normal (``normal'' 
meaning in a drop-throttle condition from the same test speed). That 
was contrasted with open-throttle stopping distances from similar 
speeds that were about 35 to 70 percent greater than normal for 
vehicles without BTO. The stopping distance improvement for vehicles 
with BTO compared to those without BTO was even larger in tests in 
which the brake pedal was modulated or ``pumped''. When combined with 
an open throttle, pumping of the brakes increases the pedal force 
needed to stop a vehicle, and this seems to be a fairly common 
occurrence in stuck accelerator pedal situations according to complaint 
narratives in the ODI database.

    \16\ See test summary ``Results of NHTSA Stopping Distance Tests 
of Production Brake-Throttle Override Systems'' at the beginning of 
the notice.

    In order to ensure the effectiveness of new BTO systems, we are 
proposing an open-throttle stopping distance test. The proposed 
requirement specifies a stopping distance measurement in which the 
accelerator pedal is applied at up to 100 percent of pedal travel for 
the duration of the braking event. The procedure would consist of 
conventional stopping distance measurements in accordance with 
specifications found in FMVSS No. 135, ``Light vehicle brake systems.'' 
Where Standard No. 135 specifies that the throttle is released or the 
vehicle is placed in neutral, the vehicle would remain in gear with the 
accelerator pedal held down to as much as 100 percent of its travel. 
This represents the situation when an accelerator pedal is trapped by a 
floor mat, with 100 percent pedal application being the worst-case 
scenario. For the purposes of these tests, we are proposing that the 
minimum accelerator pedal input would be 25 percent because pedal 
inputs below that level may not produce significant vehicle 
acceleration and may not require intervention by the BTO system. (We 
note that this is merely to facilitate consistent BTO performance 
testing, and does not mean that BTO systems cannot engage at less than 
25 percent accelerator pedal input.)
    Test speeds for the proposed BTO procedure would be any speed from 
30 km/h (18.6 mph) up to as much as 160 km/h (99.4 mph). The latter is 
the maximum specified under FMVSS No. 135. The procedure carries over 
the specification in S7.6 of FMVSS No. 135 that limits test speed to 80 
percent of a vehicle's maximum speed, not to exceed 160 km/h.
    The required stopping distance would be based on one of two 
requirements in FMVSS No. 135, depending on whether the test speed was 
greater or less than 100 km/h, to reflect the fact that FMVSS No. 135 
stopping distances are somewhat different for speeds above and below 
100 km/h. For test speeds of 100 km/h or below, the stopping distance 
requirement in S7.5, ``Cold Effectiveness,'' would apply. For speeds 
above 100 km/h, the stopping distance requirement in S7.6, ``High-Speed 
Effectiveness,'' would apply.
    We propose that the BTO performance test would be conducted at 
Lightly Loaded Vehicle Weight (LLVW) as defined in S6.3 of FMVSS No. 
135. Although the Cold Effectiveness and High Speed Effectiveness 
procedures in FMVSS No. 135 specify conducting tests at both LLVW and 
GVWR, the stopping distance requirement is the same regardless of the 
loading condition. Consequently, we believe it is unnecessary to 
include the GVWR loading condition in the BTO performance test. We 
request comments with supporting data on whether there is any safety 
need for BTO performance to be measured at GVWR.
    Under S6.5.3.2 of FMVSS No. 135, for stopping distance procedures 
specifying multiple test runs, compliance is achieved if any one of the 
test runs is within the prescribed distance. This applies to the Cold 
Effectiveness and High Speed Effectiveness procedures, where six test 
runs are required for each set of test conditions. The vehicle is 
deemed to comply if at least one stop is within the required distance. 
We propose using this same methodology for the BTO performance tests.
    All other test conditions and procedures would be in accordance 
with FMVSS No. 135 specifications. This includes ambient environmental 
conditions, track conditions, and vehicle set-up. This would utilize 
existing practices to the greatest extent possible, thus reducing test 
burden and cost.
    We are proposing that the stopping distance of a vehicle in an 
open-throttle condition shall not be more than 5 percent greater than 
the required stopping distance in FMVSS No. 135, specifically as set 
forth in S7.5 for test speeds up to 100 km/h and S7.6 for test speeds 
over 100 km/h. This 5 percent margin allows for any additional stopping 
distance resulting from the delay that may be needed for the BTO system 
to engage and during which the brakes have to work against the 
powertrain drive torque. The stopping distances in FMVSS No. 135 do not 
account for any such drive torque because they are measured with the 
vehicle in neutral or with the accelerator pedal released. The 5 
percent margin represents approximately the additional stopping 
distance NHTSA found was needed in

[[Page 22649]]

our tests of BTO-equipped vehicles (the same tests cited immediately 
above) comparing their wide-open throttle stopping distance to their 
drop-throttle stopping distance at maximum FMVSS No. 135 test speeds.

D. Update of FMVSS No. 124 Disconnection Test Procedures

New Creep Speed and Coastdown Test Procedures
    We are proposing a new vehicle performance test of powertrain 
output as an optional test procedure for compliance with the FMVSS No. 
124 disconnection requirements. This procedure would measure vehicle 
speed following an ACS disconnection, so-called ``creep speed,'' as the 
criterion for compliance. Other criteria such as engine RPM were 
considered and rejected as a result of comments on the 2002 rulemaking 
effort. By evaluating vehicle speed and acceleration, the creep speed 
test will directly measure the fundamental parameter that affects 
safety with respect to vehicle accelerator controls.
    Specifically, the compliance criterion we are proposing is vehicle 
terminal speed following an ACS disconnection and removal of force on 
the accelerator pedal. In order to comply, the measured creep speed 
obtained with no accelerator pedal input would have to fall below a 
maximum allowable value, which we are proposing should be 50 km/h (31 
mph). As mentioned previously in this proposal, this speed was 
suggested by a vehicle manufacturer and was confirmed as an appropriate 
level in NHTSA's tests of two passenger cars and one light truck. It 
would accommodate typical responses of vehicle control systems to ACS 
disconnections, including limp-home modes. Our tests also confirmed 
that this level of speed corresponds to a low level of drivetrain 
torque capability and thus is easily controllable.
    Under our proposed requirement, in the worst case of a vehicle 
whose torque output following an ACS disconnection allows the vehicle 
to reach a creep speed of exactly 50 km/h, the vehicle would accelerate 
at a rate only marginally greater than it would with no ACS faults. The 
vehicle's acceleration would be limited to the equivalent of the 
aerodynamic and frictional drag forces on the vehicle at 50 km/h which, 
for light vehicles, is a small fraction of what the powertrain is 
capable of producing.
    Compliance with the creep speed requirement would be evaluated by 
selecting any accelerator pedal input (including zero input) that 
results in an initial test speed below 50 km/h. Then, following 
disconnection of the ACS and release of the accelerator pedal (if it 
was initially applied), the vehicle's speed would have to remain below 
50 km/h. We are proposing a time limit of 90 seconds for this 
procedure, meaning that the vehicle would comply if its speed does not 
exceed 50 km/h before 90 seconds have elapsed. If a vehicle is 
accelerating so slowly that it meets this requirement, then that is 
sufficient indication that it has an acceptable fail-safe response. The 
average acceleration rate to reach 50 km/h in 90 seconds is 
approximately 0.015 g's,\17\ which is a very low value considering that 
conventional passenger cars are capable of well over twenty times that 
value at low initial speeds. The 90-second time limit also will avoid 
unnecessarily prolonging the tests to wait for very slowly accelerating 
vehicles to finally reach a terminal speed. We request comment on 
whether 90 seconds is an appropriate value and, if not, what time limit 
should be substituted and why.

    \17\ `G' or `g' is a unit that refers to the average 
acceleration produced by gravity at the Earth's surface.

    For creep speed tests where the initial test speed is above 50 km/
h, we are proposing a coastdown procedure which uses as a baseline the 
coastdown time of the test vehicle with its transmission in neutral. 
This compliance criterion was suggested by a vehicle manufacturer and 
appears to be a practical and appropriate specification. Under this 
procedure, each assessment of compliance would require two test runs as 
     The first run would measure the elapsed time required for 
the test vehicle to coastdown from a selected target speed to exactly 
50 km/h in neutral gear. The coastdown time measured in this way should 
constitute a worst-case since there would be no engine braking 
(resistance to vehicle motion resulting from engine friction and 
compression, independent of the vehicle brake system) to decelerate the 
vehicle. This elapsed time would be a ``baseline'' for comparison to 
the result of the second test run.
     In the second run, conducted at the same target speed but 
with the vehicle remaining in gear, coastdown would commence following 
an induced ACS disconnection and release of accelerator pedal. As in 
the first run, elapsed time for the vehicle to decelerate to 50 km/h 
would be the measured value.
    Compliance would be determined by comparing the coastdown time in 
these two runs. The coastdown time in gear, from the second run, would 
have to be less than the coastdown time in neutral, from the first run. 
This comparison would verify that the powertrain output of the test 
vehicle in fact was reduced to a safe level, i.e., a level that 
produces less than a 50 km/h terminal speed, while at the same time 
establishing a time limitation to ensure that the rate of deceleration 
is not unreasonably low.
    As NHTSA has not had the opportunity to conduct trials using this 
methodology, we are requesting comment on any issues related to this 
proposed coastdown test procedure.
    We are proposing that the vehicle creep speed and coastdown time 
measurements would be conducted using a chassis dynamometer to impose 
road force through the vehicle's drive wheels. The general test 
parameters for this type of dynamometer testing are available in an 
industry standard, SAE J2264, ``Chassis Dynamometer Simulation of Road 
Load Using Coastdown Techniques.'' We are proposing to incorporate by 
reference portions of that SAE standard. In NHTSA compliance testing, 
the vehicle's terminal speed would be measured following an ACS 
disconnection when using the test procedures and environmental 
conditions specified in the SAE standard. For testing using a 
dynamometer, manufacturers would have the option of either measuring a 
vehicle's road load characteristic directly by use of the procedure in 
SAE J2264, or by looking up the necessary road load coefficients in an 
Environmental Protection Agency database.\18\

    \18\ See http://www.epa.gov/otaq/crttst.htm.

    A potential issue with creep speed and coast-down measurements 
conducted on a chassis dynamometer is that FMVSS No. 124 includes test 
temperatures down to as low as minus 40 Celsius (equivalent to minus 
40[deg] F). To the best of our knowledge, existing vehicle dynamometer 
facilities normally cannot achieve ambient temperatures that low. 
Therefore, we specifically request comment on whether a different lower 
limit on environmental temperature should be specified in the FMVSS for 
tests of vehicle ACSs conducted using a dynamometer facility.
    We are proposing that the new creep speed test also could be 
conducted on a test track, to the extent that a suitable test area with 
adequate straightaway space is available. When starting from a high 
speed in the coastdown portion of the proposed test procedure, a 
vehicle may coast for a number of minutes. The

[[Page 22650]]

required length of the test area could easily be on the order of a mile 
or more. This may limit the feasibility of substituting a track test 
for a dynamometer test.
    For a track test, the test area should meet a maximum slope 
specification since any significant grade could affect test outcome. 
Furthermore, in order for the test to be repeatable, wind conditions 
would have to be light, and air temperature should also be within a 
limited range because these factors influence aerodynamic drag. We are 
proposing the following conditions for creep and coastdown speed 
measurements conducted on a test track:
     Straight course of dry, smooth, unbroken concrete or 
asphalt pavement with a continuous grade of not more than 0.5 percent 
in any direction;
     Ambient temperature between 5 C (41 [deg]F) and 32 C (90 
     Average wind speed no greater than 16 km/h (10 mph) with 
gusts no greater than 20 km/h (12 mph) and with the wind velocity 
component perpendicular to the test direction no greater than 8 km/h (5 
    To the best of our knowledge, these conditions are consistent with 
current industry practice for this kind of testing. We request comment 
on these proposed conditions, specifically any information to support 
why NHTSA should consider different test conditions.
    We believe that this new method of compliance is a necessary 
addition to FMVSS No. 124 that fulfills the need for a ``technology 
neutral'' test that can be applied to any type of wheel-driven motor 
vehicle regardless of the type of propulsion system it uses. This 
procedure is performance-based and uses established vehicle test 
methods that should be familiar to the industry. Therefore, we believe 
that this new proposed procedure is both practicable and objective.
New Air Intake and Fuel Delivery Rate Tests
    This proposal includes a fuel delivery rate test procedure as in 
the 2002 NPRM. It also includes a new air intake rate test procedure 
that was not included in the 2002 NPRM. This procedure was suggested in 
comments as an alternative that will expedite testing of some vehicles. 
It is identical to the fuel rate test, but uses mass airflow rate 
rather than fuel flow rate to quantify the state of vehicle power 
output and whether the engine is at idle.
    These test procedures are logical extensions of the traditional 
throttle position test. For most existing gasoline engines, throttle 
position indicates (and in fact controls) the rate of intake of air/
fuel mixture into the engine which, in turn, determines engine power 
output. Since the air/fuel ratio stays relatively constant over the 
engine's operating range, observing either the fuel intake rate or air 
intake rate also provides a valid indicant of engine output, and either 
quantity can substitute for throttle position. In effect, fuel rate, 
air intake rate, and throttle position are equivalent for FMVSS 124 
purposes in that they each can indicate whether the engine is at idle.
    For diesel engines, the traditional FMVSS 124 test indicant is the 
fuel rack position which determines fuel flow. (The fuel rack is the 
mechanical linkage on older diesel engines that moves back and forth 
when the accelerator pedal is pressed and released; its operation is 
analogous to a mechanical throttle linkage on a gasoline engine.) Fuel 
rack position corresponds to fuel intake rate, so we are proposing 
that, on modern diesels without a fuel rack, the net fuel delivery rate 
is the appropriate engine power indicant. Diesels operate on excess 
intake air unlike a gasoline engine, so power output cannot necessarily 
be gauged by air intake rate alone. We request comment as to the 
appropriateness of air intake rate as a measurement criterion for 
diesel engines, and also whether there are other possibilities for 
diesels besides those we have considered here.
Components Included in an Accelerator Control System
    In interpretation letters on FMVSS No. 124 which responded to 
questions about which parts of an ETC system are considered ACS 
components, we treated an ACS as a series of linked components 
extending from the driver-operated control to the throttling or fuel-
metering device on the engine or motor. Electronic systems using wires, 
relays, control modules, and electric actuators joining the accelerator 
pedal to the throttle or injectors on the engine are analogous to 
mechanical systems in which levers, cables, and springs serve the same 
purpose. We indicated that a severance at any one point in the system 
should not result in a large increase in engine power, and that this 
also applies to an ACS that mixes mechanical and electronic components.
    Nevertheless, an ETC system is less easily defined than a 
mechanical one because a variety of components can influence engine 
speed without being in the direct line of action between the 
accelerator pedal and the throttling device on the engine. As in the 
2002 NPRM, we see two basic approaches for defining the items included 
in an electronic ACS.
    One approach would be to list in the regulatory text of the 
Standard each and every component, including each conductor, connector, 
module, etc., which is subject to the fail-safe requirements. This 
explicit approach would provide a high degree of specificity, but would 
lack flexibility. It carries a significant risk that a connective 
component omitted from specific mention in the standard would be 
excluded from regulation, even if the omission was unintentional.
    An alternative approach, and the one that we have chosen to adopt 
in this proposal, is to specify in general terms the connective 
components that are regulated. This approach lends a greater degree of 
flexibility and leaves open the possibility that the regulatory 
language can be adapted to new technology. The covered ACS parts still 
would be limited to ``connective components'' only, so we believe that 
using this general approach does not diverge from the scope of the 
existing Standard.
    We are listing here some common components of an ACS to illustrate 
the intent of the proposed Standard and to make it widely acknowledged 
that these components are considered connective components of an ACS. 
This is not intended to be an all-inclusive list. The following 
enumerates some of the connective components for both mechanical and 
electronic systems that we believe must comply with the disconnection 
requirements of FMVSS No. 124:
 Components of an Air- or Fuel-Throttled Engine
    The critical connective components of the ACS are: (1) The springs 
or other sources of stored energy that return the driver-operated 
control and the throttle to their idle position; (2) the linkages, 
rods, cables or equivalent components which are actuated by the driver-
operated control; (3) the linkages, rods, cables or equivalent 
components which actuate the throttle; (4) the hoses which connect 
hydraulic or pneumatic systems within an ACS; (5) the connectors and 
individual conductors in the electrical wiring which connect the 
driver-operated control to the engine control processor; (6) the 
connectors and individual conductors in the electrical wiring which 
connect the ECM to the throttle or other fuel-metering device; and (7) 
the connectors and individual conductors in the electrical wiring which 
connect the ECM to the electrical power source and electrical ground.
    The ECM itself is also included as a single component of an 
electronic ACS. However, as before, we treat the fail-safe (i.e., 
disconnection) requirements of the

[[Page 22651]]

Standard as pertaining to the external connections to and from the ECM. 
We consider the internal elements of the ECM to be like the internal 
elements of a carburetor or throttle body injector, which are not 
subject to the fail-safe requirements of the Standard. The wiring and 
connectors between the pedal position sensor and the ECM, the wiring 
and connectors between the ECM and the fuel or air throttling device on 
the engine, and the power and ground connections to the ECM all qualify 
as connective elements rather than internal ones.
 Components of an Electric Propulsion System's ACS
    For an electric motor-driven vehicle, the critical connective 
components of an ACS are: (1) Springs or other sources of energy that 
return the driver-operated control and the motor speed controller to 
the idle position; (2) linkages, rods, cables or equivalent components 
which are actuated by the driver-operated control; (3) linkages, rods, 
cables or equivalent components which actuate the motor speed 
controller; (4) hoses which connect hydraulic or pneumatic actuators 
and components within the ACS; (5) connectors and individual conductors 
in electrical wiring connecting the driver-operated control to the 
motor speed controller or motor control processor; (6) connectors and 
individual conductors which connect the motor control processor to the 
motor speed controller (if they are separate modules); (7) connectors 
and individual conductors in the electrical wiring which connect the 
motor control processor to electrical power and ground; and (8) the 
connectors and individual conductors in the electrical wiring from the 
motor speed controller to the electric traction motor.
Definition of Idle State
    Based on comments NHTSA received on the 2002 NPRM, manufacturers 
would prefer that the Safety Standard allow the manufacturers to 
determine what is an acceptable idle state. Manufacturers consistently 
commented that the idle state varies according to a number of factors 
such as engine temperature, accessory load, emission controls, and 
altitude. It may not be possible to specify fixed values for throttle 
position, engine speed, fuel rate, etc., because those characteristics 
can change according to many conditions without any input from the 
accelerator pedal. They pointed out that limp-home modes can adjust 
engine operation to prevent stalling and to provide enough power for a 
vehicle to be moved from an unsafe location in the event of a 
    The current Standard accommodates a range of idle state values by 
allowing any throttle position ``appropriate for existing conditions.'' 
In a traditional air-throttled engine which has a mechanical throttle 
stop that designates the idle position of the throttle, the throttle 
stop can change position as dictated by operating conditions. For 
example, it may move to a position of increased throttle opening when 
the engine is cold. In testing, the throttle stop provides a convenient 
reference position that makes determination of compliance a simple 
    Vehicle manufacturers recommended that idle state should be a 
manufacturer-specified data item provided to NHTSA for each compliance 
test. Under this approach, each manufacturer would specify a value or 
range of values for the applicable idle state indicant for each of its 
    After considering the comments, we are not persuaded that this 
approach is the best solution to the question of how to define an 
appropriate idle state value. We believe it would be burdensome to have 
to obtain idle state data from manufacturers for each test vehicle, 
potentially for numerous possible operating conditions.
    Instead, we believe it is easier and more practical to establish a 
baseline idle state simply by measuring the initial value of the 
applicable idle state indicant (throttle position, fuel delivery rate, 
electrical power input, etc.) at the beginning of a compliance test 
(i.e., immediately before any fault is induced). This initial value 
would be an appropriate baseline because it would account for whatever 
operating conditions exist at the time a test takes place. It is 
convenient because it is measured directly as part of the test 
procedure, and it does not depend on information provided by vehicle 
    Once the baseline is established, the value of the idle state 
indicant at the end of the test is expected to be the same as or close 
to the baseline value established at the start of the test (within a 
tolerance range, as defined below). Compliance is indicated by whether 
or not the idle state returns to the baseline value within the elapsed 
time specified in S5.3 of the regulatory text.
    This approach is valid only if operating conditions such as engine 
temperature, accessory load, etc., are fairly constant during a test 
since adjustments made by an electronic control system to compensate 
for changes in conditions would not be observable but rather would take 
place within the ECM. Consequently, it could be difficult to 
distinguish between a permissible increase in idle state and a 
noncomplying one.
    In order to address this, NHTSA's proposal specifies that operating 
conditions must be held constant to the greatest extent possible during 
fail-safe tests in order to minimize variations in engine idle that are 
not due to an ACS disconnection. In a compliance test, the engine must 
be stabilized and all accessory controls fixed so that conditions that 
affect idle state do not change significantly during the course of the 
test. This includes operating the engine long enough to deactivate cold 
start features as well as to stabilize emission controls. We have 
specified that the engine must be operated for at least 5 minutes prior 
to any measurement of idle, as this should be sufficient to achieve a 
reasonably steady idle state. We request comment whether 5 minutes is 
an appropriate value.
    For some operating characteristics such as ``variable 
displacement'' or cylinder de-activation modes, we recognize that 
maintaining a constant operating condition may not be straightforward. 
It would be acceptable to either prevent engagement of these kinds of 
features during testing or to ensure that they do not change the idle 
state during testing. We request comment on what means are available to 
ensure that features like cylinder deactivation do not influence test 
    Under today's proposal, the baseline value is established by 
observing the idle state indicant for an engine with a normally 
functioning ACS. For the ``normal operation'' requirement, the 
compliance criterion would be the time to return to the baseline value 
from the moment of release of the accelerator pedal from any position 
within its full range of movement. For the ``fail-safe'' requirement, 
the idle state following a disconnection in the ACS is compared to the 
baseline value to ensure that it is close to (i.e., within the 
tolerance) or below the baseline. The time elapsed from the moment of 
the disconnection and pedal release for the measured value to return to 
the baseline value must be within the Standard's specified time spans 
(1 second for light vehicles). With the engine operating in a steady 
state with accessory controls at fixed settings, any difference in the 
``before and after'' idle states should be attributable to the induced 

[[Page 22652]]

Two Sources of Energy for Returning Throttle to Idle
    At present, FMVSS No. 124 states in S5.1, ``there shall be at least 
two sources of energy capable of returning the throttle to the idle 
position'' within the specified time limits from any accelerator 
position or speed, whenever the driver removes the actuating force on 
the accelerator pedal. It also specifies that, whenever one source of 
energy fails, the other shall be able to return the throttle to idle. 
In the past, springs have been the predominant sources of energy for 
return to idle. That appears to still be the case for accelerator pedal 
assemblies of vehicles with electronic accelerator controls and for 
throttle bodies. These assemblies usually incorporate multiple springs, 
and testing of fail-safe operation would still include disconnection of 
each single spring.
    However, because the standard requires return-to-idle regardless of 
whether there are two sources of energy present, this requirement may 
be considered superfluous. Most if not all manufacturers will continue 
to provide two or more return springs on accelerator pedal assemblies 
and throttle bodies whether or not there is an explicit requirement for 
it because it is a simple way of meeting the ``single-point 
disconnection'' requirement when one of the springs is disconnected.
    As we have noted elsewhere in this proposal, our letters of 
interpretation have stated that, although having two or more springs on 
a pedal assembly is a good idea, that alone is not sufficient to ensure 
compliance with the FMVSS No. 124 fail-safe requirements. For example, 
dual springs on the pedal assembly would be irrelevant if the 
assembly's electrical connector was disconnected.
    For these reasons, we believe it may be appropriate to delete the 
requirement for two sources of energy which return the throttle to 
idle. We request comment on this issue.
    Under today's proposal, the single-point disconnection requirement 
is applicable to any source of throttle return energy connected to the 
ACS. This includes electric motors and actuators, solenoids, and other 
electrically powered devices. The electric power source for these 
components would be considered a ``source of energy'' for closing the 
throttle, and thus the power and ground leads for these components 
would be subject to disconnection.
Criteria for Return to Idle in Normal Operation
Engines With a Traditional Throttle Plate
    Like the previous NPRM, this proposal retains return of a throttle 
plate to the idle position as the criterion for normal operation of 
air-throttled engines with a traditional throttle. This criterion is 
still valid for many gasoline engines with either mechanical or 
electronic accelerator controls, and probably will continue to be for 
the foreseeable future.
Diesel Engines
    For diesels (and other fuel-throttled engines), this proposal 
provides fuel delivery rate (gallons/hour of fuel entering the 
combustion chambers of the engine) as a measure of idle state. It 
requires return of the fuel rate to the idle fuel rate as a measure of 
return-to-idle. For diesel engines, power is controlled directly by 
controlling fuel flow. The result of rapidly releasing the accelerator 
control is a rapid return of the fuel rate to the steady idle rate, and 
there is no need to account for the time lag required for the engine 
speed to return to idle. In this respect, the fuel rate of fuel-
throttled engines is analogous to the throttle position of air-
throttled engines.
Engines With Unitized Injectors
    An engine with self-contained, integrated fuel injectors (called 
``HEUI'' injectors for High Energy Unit Injector), now commonplace in 
commercial trucks, is potentially problematic with respect to return to 
idle criteria because it has multiple ``throttles,'' those being its 
individual injectors, which can operate independently of each other. 
However, fuel flow rate for these engines generally can still be used 
to quantify the operational state of the engine. The fuel rate combines 
the action of the individual injectors and represents the steady effect 
of all the injectors' dynamic duty cycles (percent open time or pulse 
width and frequency). It also avoids the problem of the lack of a 
visibly observable throttle reference position. Fuel rate thus provides 
a satisfactory return-to-idle indicant for modern diesel engines with 
electronic fuel systems.
    For light vehicles, similar fuel control arrangements may become 
more prevalent as diesels become more common and direct-injection 
gasoline engines enter the marketplace. We believe these vehicles will 
be able to comply by either the fuel rate test or one of the other 
available test procedures described in this proposal.
    For many heavy vehicles, we understand that a fuel rate signal 
which consolidates the effect of fuel pressure and fuel injector duty 
cycle is available as a standardized diagnostic channel. For engines 
without this diagnostic signal, direct measurement of fuel flow in the 
supply and return lines would be necessary to ascertain the net fuel 
Electric Motors
    For vehicles which use electric motor propulsion, the electric 
power input at the drive motor (computed from voltage and current) 
would be used as the indicant idle state. This measurement responds 
directly to the operation of the motor controller which, like a 
unitized electronic fuel injector, is a throttle without a measurable 
reference position. Since drive torque is directly proportional to the 
drive motor input current and voltage, this indicant is equivalent to 
throttle position. Alternative measurement criteria used for non-
electric vehicles such as fuel delivery rate are not applicable to 
electric vehicles, but we request comment on whether there are any 
other measurement criteria that would be appropriate for electric 
No Normal Operation Test Corresponding to Creep Speed Method
    Unlike the test procedures for throttle position, fuel delivery 
rate, air intake rate, and electric power delivery, the creep speed 
test does not have a corresponding normal operation criterion. This was 
the subject of at least one comment on the 2002 NPRM that suggested 
that an engine output criterion should be provided for normal as well 
as fail-safe operation. However, establishing a normal operation 
requirement based on creep speed would require restricting aspects of 
vehicle performance such as engine braking effect that have never been 
part of FMVSS No. 124 or any other NHTSA regulation. For example, a 
normal operation requirement for creep speed might specify that a 
vehicle has to coastdown to a speed of `X' from an initial test speed 
of `Y' in `Z' seconds. This would place restrictions on vehicle rolling 
resistance and engine-braking that are unrelated to safety. Therefore, 
a creep speed-based normal operation requirement is not feasible under 
FMVSS No. 124.
    Consequently, if a manufacturer selects the creep speed procedure 
to certify to the fail-safe requirement, a different procedure would 
have to be selected to certify to the normal operation requirement.

[[Page 22653]]

Response Time for Normal Operation
    This proposal maintains the existing requirement that, in normal 
operation (i.e., without faults in the ACS), return to idle must occur 
within 1 second after release of the accelerator pedal for light 
vehicles, and within 2 seconds for heavy vehicles (over 10,000 lb. 
GVWR). The required response time is 3 seconds if the test vehicle is 
exposed to temperatures of minus 18 Celsius or lower during any portion 
of the 24-hour conditioning period, for both light and heavy vehicles.
Fail-Safe Performance Criteria
    Because electronic ACSs can use various means to reduce vehicle 
power in response to an ACS disconnection, our intent in this proposal 
is to allow manufacturers to take advantage of those possibilities by 
establishing fail-safe criteria that are performance-oriented rather 
than design-oriented.
Powertrain Output ``Creep Speed'' Test Option
    We have included in S6.5 of the proposed regulatory text a new 
``technology-neutral'' powertrain output test performed on a 
dynamometer or test track, as described previously in this document 
(see ``New Creep Speed and Coastdown Test Procedures'' under section VI 
D, above). This test of fail-safe response is performance-based and 
independent of powertrain design, i.e., it is valid for any type of 
powertrain in any wheel-driven vehicle. It provides a universal 
measurement criterion, i.e., maximum vehicle terminal speed, that has 
direct relevance to the safety purpose of FMVSS 124. The new creep 
speed and coastdown procedures require that a test vehicle cannot 
accelerate appreciably if its initial speed is below 50 km/h and must 
decelerate if its initial speed is above 50 km/h upon release of the 
accelerator pedal following an ACS disconnection. The new creep speed 
and coastdown procedures appear in section S6.5 of the regulatory text 
of this rule which specifies controlled test conditions for accurate 
exertion of road load on the drivetrain.
Fail-Safe Performance Test for Air-Throttled Engines
    For air-throttled engines, return of the throttle plate to the idle 
position is the least burdensome test for many vehicles in current 
production. This alternative is identical to the procedure of the 
present Standard. A second alternative is return of the fuel rate to 
the idle state. For air-throttled engines, engine power cannot vary 
substantially from the idle state if the fuel rate is constrained to 
the value observed at the idle state. Thus, fuel delivery rate is a 
reliable indicant that engine power is constrained. Similarly, a third 
alternative is mass airflow rate through the intake manifold. Air 
intake rate behaves like fuel delivery rate for vehicles whose fuel-air 
ratio stays relatively constant as operating conditions vary. Thus, air 
intake rate is also an acceptable indicant of engine power output.
Fail-Safe Performance Test for Fuel-Throttled Engines
    Since fuel-throttled engines such as diesel engines may operate 
with excess intake airflow, neither the position of an air throttle, if 
one is present, nor the air intake rate would be an accurate indicant 
of engine power. Fuel delivery rate, on the other hand, is an accurate 
and sufficient indicant of engine power for these engines in most 
cases. The same fuel delivery rate criterion specified for evaluating 
compliance in normal operation of fuel-throttled engines is included in 
this proposal as an optional test for fail-safe performance.
    Some modern diesel and gasoline direct injection engines may inject 
additional small amounts of fuel during a single injection cycle. This 
extra fuel does not contribute to propulsion, but is intended to smooth 
engine operation or to meet emissions requirements. If vehicles with 
these types of engines could not be adequately tested using the fuel 
delivery rate procedure, then the optional creep speed procedure would 
be an appropriate alternative since that test is not sensitive to any 
particular fuel delivery characteristics.
Fail-Safe Performance Test for Electric Vehicles
    For vehicles driven solely by electric motors, we are proposing 
that an optional test of fail-safe performance be the same as the 
normal operation criterion, i.e., return of the drive motor electric 
power input to the idle state. This procedure can also be applied to 
the electric drive motor of a hybrid vehicle.
Fail-Safe Performance Test for Hybrid Vehicles
    For a hybrid vehicle that combines more than one type of propulsion 
system, the most applicable test procedure would be the creep speed 
test which would evaluate the net driving effect of the various 
propulsion systems working together. Alternatively, fail-safe 
performance of each separate engine's or motor's accelerator controls 
could be demonstrated independently using test options appropriate for 
each type of propulsion system. For example, on a gas-electric hybrid, 
the gas engine might be tested by measuring the throttle position while 
the electric motor is tested by measuring current and voltage.
Response Time Requirements for Fail-Safe Operation
    The required response times for the idle state indicant to return 
to or near the baseline value following an ACS disconnection are the 
same as those given in the current Standard and also for normal 
operation of the ACS. For light vehicles (under 10,000 lb GVWR), return 
to idle must occur within 1 second after ACS disconnection and release 
of the accelerator pedal, or, within 2 seconds for heavy vehicles (over 
10,000 lb. GVWR). The required response time is 3 seconds if the test 
vehicle is exposed to temperatures of minus 18 Celsius or lower during 
any portion of the 24-hour conditioning period, for both light and 
heavy vehicles.
    For the proposed creep speed procedure, compliance is not based 
directly on the time required for an idle state indicant to return to 
idle. Instead, for test speeds at or below 50 km/h, compliance is based 
on whether the vehicle's terminal speed remains below 50 km/h for at 
least 90 seconds after an ACS disconnection; for test speeds greater 
than 50 km/h, compliance is based on whether the time required to coast 
down to 50 km/h is greater or less than the coastdown time in neutral 
from the same test speed.

E. Compliance Options for Various Vehicles

    Our proposal would require manufacturers to specify one of the 
following criteria as the basis for certifying a vehicle to the 
requirements of S5.1 (normal operation) and S5.2 (fail-safe operation) 
of the standard: Throttle position, fuel delivery rate, air intake 
rate, electric power delivery, and creep speed/coastdown performance. 
The selection would be at the option of the manufacturer. However, 
while one of the criteria, creep speed/coastdown performance, could be 
used for any vehicle, the appropriateness of the other criteria would 
depend on the nature of the vehicle. For example, an electric vehicle 
could be certified based on electric power delivery in addition to 
creep speed/coastdown performance, and a vehicle with a gasoline engine 
could be certified based on throttle position, fuel delivery rate, and 
air intake rate, as well as creep speed/coastdown performance. We 
believe it is appropriate to permit multiple options to manufacturers 
so long as each option

[[Page 22654]]

would meet the relevant safety need. We request comments on the 
appropriateness of each of the proposed options; the possibility of a 
manufacturer seeking to use an option that might not be appropriate for 
a vehicle given the characteristics of the vehicle and, if so, the 
safety consequences; and whether there is a need for the regulation to 
limit any of the options to vehicles with particular characteristics.

VII. Safety Benefits and Crash Data

    A rule based on today's proposal would be expected to prevent most 
crashes resulting from accelerator pedal entrapment, including floor 
mat incidents. The accidents that could be avoided are similar to 
highly publicized crashes that have played a key role in the escalation 
of UA as a nationally recognized safety problem.
    With regard to the ACS disconnection requirements, any benefits 
associated with the original FMVSS No. 124 safety standard would be 
unchanged by this proposal.

A. Summary of Crash Data on Accelerator Control Issues

    Three of NHTSA's crash datasets were identified as potential 
sources of information about possible accelerator control issues in 
passenger vehicles: Fatality Analysis Reporting System (FARS), National 
Motor Vehicle Crash Causation Survey (NMVCCS), and National Automotive 
Sampling System--Crashworthiness Data System (NASS-CDS). FARS is an 
annual census of fatal traffic crashes based upon secondary data 
sources such as the police accident report. NMVCCS was a one-time three 
year special study of crashes involving at least one passenger vehicle 
towed due to damage and investigated by NHTSA with an emphasis on pre-
crash factors. NASS-CDS is an annual sample of crashes involving at 
least one passenger vehicle towed due to damage and investigated by 
NHTSA with an emphasis on crashworthiness factors. Overall these 
databases each contain cases involving an allegation of a stuck 
accelerator or throttle, and the available information is summarized 
below. However, each of these sources also has limitations that should 
be considered when using the results.
Fatality Analysis Reporting System (FARS)
    FARS is a nationwide census providing yearly data regarding fatal 
injuries suffered in motor vehicle traffic crashes. FARS records when a 
pre-existing vehicle defect or condition is noted in police accident 
report (PAR) as a vehicle related factor. According to the FARS Coding 
and Validation Manual, ``the report may indicate that a component is 
inadequate, inoperative, faulty, damaged or defective.'' The FARS 
Manual also cautions that the presence of a vehicle related factor 
``only indicates the existence of the condition(s)'' and that the 
condition ``may or may not have played a role in the crash.''
    The most relevant vehicle related factor in FARS to identify 
possible accelerator control issues is ``power train.'' The code for 
``power train'' includes the following components: universal joint, 
drive shaft, transmission, engine, clutch and gas pedal. In the 2009 
data there were seven light passenger vehicles with the presence of a 
power train related factor involved in seven fatal crashes resulting in 
ten fatalities.
    Because of the inclusion of many different components and 
situations in the category of powertrain, researchers must request the 
PAR from the State and review the narrative sections to extract 
additional information. However, in this case, analysis of these seven 
PARs indicated that the police reports did not typically contain useful 
information for understanding whether the accelerator control was a 
factor in the crash. Our analysis also indicated that many of the 
reports with this designation involve vehicles that stalled.
National Motor Vehicle Crash Causation Survey (NMVCCS)
    NMVCCS was a nationwide survey of crashes involving light passenger 
vehicles, with a focus on the factors related to pre-crash events. A 
total of 6,949 crashes were investigated between January 1, 2005, and 
December 31, 2007. Of these, 5,470 cases comprise a nationally 
representative sample. The remaining 1,479 cases are suitable for 
clinical study. Each investigated crash involved at least one light 
passenger vehicle that was towed due to damage.
    The advantage of NMVCCS over FARS for identifying possible 
accelerator control issues is twofold. The first is that the data in 
NMVCCS are based upon the investigation of a researcher trained to 
focus on pre-crash events rather than exclusively on secondary sources 
such as the PAR. The second is that NMVCCS contains a more specific 
vehicle related factor. According to the NMVCCS SAS Analytical Users 
Manual, the vehicle related factor of ``engine'' in NMVCCS ``documents 
if the vehicle experienced an engine related problem during the pre-
crash phase. Examples of engine related problems include stalling, 
missing, and throttle problems.'' There were 26 cases that included a 
vehicle with an engine related problem--20 in the nationally 
representative sample and 6 among the case studies. After reading the 
crash narratives associated with these cases, most of them involved 
engines that stalled or overheated. Only three cases involved a problem 
with the accelerator control: Case numbers 2005074596262, 2007008450848 
and 2007079486127. The first case involved a 1984 Oldsmobile Cutlass 
that was known to have an accelerator problem before the crash. The 
driver reported that ``the vehicle would not remain running unless [he] 
held [his] foot on the gas and then [put] the vehicle into gear'' and 
that while doing this right before the crash ``the accelerator stuck at 
full throttle.'' The second case involved a 1994 Chevrolet Corvette 
that the driver reported was not running properly. The driver ``tried 
to feather the gas, upon doing so the gas pedal stuck down.'' The 
driver lost control while braking and steering. The third case involved 
a 1965 Ford Mustang where the ``accelerator became stuck and the 
vehicle accelerated to approximately 129 km/h (80 mph).'' The driver 
lost control and left the roadway after applying the brakes. Only two 
of these three cases were part of the nationally representative sample, 
and there are not enough cases to accurately estimate a sample size for 
the problem.
National Automotive Sampling Survey--Crashworthiness Data System (NASS-
    NASS-CDS is an annual nationally representative sample of traffic 
crashes involving at least one passenger vehicle towed due to damage. 
The advantage of NASS-CDS is that many years of data can be examined, 
and this analysis focuses on the most recent ten years (2000 through 
2009). A limitation, however, is that NASS-CDS does not have a coded 
variable to search for possible accelerator control factors. Instead, 
the identification of potentially relevant cases is based upon 
searching the crash narrative for key words. A caveat associated with 
this search is that the potential accelerator control issue must be 
mentioned in the crash narrative and the key words must be able to 
identify these cases.
    A search of the crash narrative for ``throttle,'' ``accelerator'' 
or ``gas pedal'' resulted in 44 cases from 2000 through 2009. However, 
in many of these cases the person applied the gas pedal rather than the 
brake. In a few cases the driver's foot struck the accelerator usually 
because of a medical condition

[[Page 22655]]

such as a seizure but sometimes because of the foot becoming trapped or 
wedged. However, eleven cases during the ten-year period indicated an 
accelerator control issue. Additional searches were conducted for 
``racing,'' ``acceleration'' and ``runaway'' to find cases related to 
racing engines, sudden or UA and runaway vehicles. However, these 
searches did not produce any additional relevant cases.
    The following table summarizes the results, including a brief recap 
of the accelerator control issue as described in the narrative:

                  Make                                    Model                      MY            Notes
Chevrolet..............................  Corvette...............................     1995  The PAR reported the
                                                                                            throttle had stuck
                                                                                            open for some
Oldsmobile.............................  Cutlass................................     1989  Vehicle throttle
                                                                                            stuck open.
Oldsmobile.............................  Ciera..................................     1990  The driver of the
                                                                                            vehicle has
                                                                                            indicated that his
                                                                                            accelerator pedal
                                                                                            stuck causing the
                                                                                            loss of vehicle
Ford...................................  F-Series Pickup........................     1997  The driver stated the
                                                                                            accelerator stuck.
Chevrolet..............................  C/K/R/V-Series Pickup..................     1988  The driver
                                                                                            experienced a
                                                                                            problem with the
                                                                                            attempted to stop at
                                                                                            the marked
                                                                                            intersection, but
                                                                                            was unable to stop.
Buick..................................  LeSabre................................     1989  The driver stated
                                                                                            that the accelerator
                                                                                            stuck and he could
                                                                                            not stop the
Pontiac................................  Bonneville.............................     2002  The PAR related the
                                                                                            driver was driving
                                                                                            in lane one of the
                                                                                            three-lane, one-way
                                                                                            street when the
                                                                                            accelerator stuck
                                                                                            and the driver took
                                                                                            evasive action and
                                                                                            steered the vehicle
                                                                                            to the left so he
                                                                                            would not run out
                                                                                            into traffic. But
                                                                                            the interview stated
                                                                                            the driver was
                                                                                            parked on the right
                                                                                            side of the road and
                                                                                            when he started up
                                                                                            the vehicle it took
Chevrolet..............................  Cavalier...............................     1990  The vehicle's
                                                                                            accelerator stuck
Chevrolet..............................  Blazer.................................     1996  A portable oxygen
                                                                                            tank fell onto the
Ford...................................  Bronco.................................     1985  The accelerator of
                                                                                            vehicle got stuck.
Infiniti...............................  J30....................................     1993  The driver claimed
                                                                                            the accelerator

    Overall it appears that the claims of accelerator control issues 
span a variety of vehicle models and model years. Also, in most cases, 
the only information available about the nature of the problem is a 
claim that an accelerator or throttle ``stuck'' while the vehicle was 
in motion. In some cases the narrative explicitly mentioned that the 
driver tried to stop but could not. Two of the eleven cases do not fit 
the general pattern of a stuck accelerator with little additional 
information. In one case an oxygen tank fell on the accelerator, and 
the driver was unable to stop the vehicle. In another case, there were 
conflicting reports of whether the driver could not stop a moving 
vehicle or whether the vehicle suddenly accelerated from a stopped 
    There are several reasons that NASS-CDS is not particularly useful 
for providing national estimates of the incidence of accelerator 
control issues. As mentioned previously, searching for key words in the 
narrative requires that the information be recorded in the narrative 
and that the key words are capturing all of the appropriate cases. A 
second reason is that the information available in the narrative is 
usually just the claim of a stuck accelerator or throttle with little 
additional information to understand the nature of the problem. A final 
reason is that the sample size of eleven cases over ten years is not 
sufficient for accurately estimating the problem size. Nevertheless, to 
the extent that we are able to identify in NASS-CDS some cases where an 
accelerator pedal became stuck, along with out test track assessment of 
vehicles with the technology, we believe brake-throttle override would 
be a solution for mitigating the subsequent crashes that occurred.
    Because the FARS, NASS, and NMVCSS data are of limited usefulness 
for estimating harm caused by ACS-related failures, we cannot estimate 
the safety problem on a national level. However, based on media 
reports, our analysis of recent ODI complaint data, observations from 
NASA's review of certain Toyota vehicles, and NHTSA's history with 
floormat issues and other types of problems that prevent an accelerator 
pedal from responding normally, we believe this rulemaking is 

B. Owner Complaint Data

    The Office of Defects Investigation (ODI) is the office within 
NHTSA responsible for conducting defect investigations and 
administering safety recalls in support of NHTSA's mission to improve 
safety on our nation's roadways. One important means by which ODI 
discovers vehicle safety-related defects is self-reporting by vehicle 
owners. By relating the information over a toll-free hotline or by 
filling out a VOQ on-line,\19\ vehicle owners can provide complaint 
information that is entered into ODI's vehicle owner complaint 
database. This information is used with other complaints and 
information to determine if a safety-related defect trend exists.

    \19\ The VOQ form and other information about filing a complaint 
can be found at the following NHTSA-administered Web site: 

    Our analysis and discussion of stuck and trapped accelerator pedals 
in today's notice is exemplified by ODI VOQs because consumers have 
described crashes or incidents involving a vehicle speeding out of 
control with a stuck accelerator pedal. These incidents cannot be 
identified readily from data elements in NHTSA's traditional crash data 
sources (as discussed in the previous section) or there are too few 
cases available in those databases. In addition, one of the specific 
observations made by the NASA in its report to NHTSA on Toyota 
unintended acceleration stated that some VOQs indicate that drivers may 
not know or understand the vehicle response when they attempt to 
control a runaway vehicle, i.e., that the high engine speed resulting 
from a shift to neutral will not harm the vehicle, or that pumping 
vacuum-assisted brakes can decrease their effectiveness.\20\

    \20\ See Observation O-1 in section 7.2, page 172, of the NASA 
report at: http://www.nhtsa.gov/PR/DOT-16-11.

    There are important qualifications in the use of VOQs as a data 
source for conducting rulemaking. Among them are:
     VOQs are self-reported data, meaning that the information 
they contain is dependent on the description of an incident provided by 
the driver, another involved party, or someone related.

[[Page 22656]]

     There may be no follow up investigation to verify what 
actually happened or to make an objective analysis of the root cause of 
a crash. However, in the case of complaints involving UA, ODI did do 
extensive follow-up work, mostly in connection with defect 
investigations that were opened, and attempted to confirm, for example, 
if there was evidence of floor mat interference contributing to a UA 
     Important facts about other possible contributing factors 
in these incidents may be unavailable.
     The crashes and incidents reported are not randomly 
selected (random selection is a normal prerequisite for statistical 
analysis.) In the case of UA incidents, selection depended partly on 
which vehicles were involved in ODI investigations.
     Many relevant incidents may be unreported because the 
driver or other party chose not to file a complaint or did not know how 
or where to do so.
     The numbers of complaints relating to any safety problem 
may either under-represent or over-represent the extent of the problem 
on a national level.
    VOQs can, however, help to identify emerging safety issues and 
problems that drivers are having, which is appropriate for what we are 
trying to address with this proposal. NHTSA's analysis and breakdown of 
UA complaints is available in the February 2011 NHTSA report, 
``Technical Assessment of Toyota Electronic Throttle Control (ETC) 
Systems,'' \21\ Section 2. Using a broad keyword search and manual 
review of the results, NHTSA identified a total of 9,701 UA incidents 
of all types involving model year 1998-2010 vehicles reported in VOQs 
between January 1, 2000, and March 5, 2010. It was possible to identify 
the UA initiation speed in 5,512 of those incidents, and a crash was 
indicated in 2,039 of the 5,512. Of those crashes, 16 percent had 
either medium or high initiation speed (defined as at least 15 mph or 
45 mph, respectively).

    \21\ The report is available on the internet at: http://nhtsa.gov/staticfiles/nvs/pdf/NHTSA-UA_report.pdf.

    Although we do not know how many of those complaints are 
attributable to UA resulting from stuck or trapped accelerator pedals, 
there are many examples of VOQs which indicate that the accelerator 
pedal was stuck, or something to that effect, including some that 
specifically mention floor mat entrapment. A few of these go into 
greater detail, describing harrowing incidents that exceed a minute in 
duration, include swerving in and out of traffic, and are accompanied 
by severe heat damage to the brakes. While these are relatively 
uncommon compared to overall crash/incident risk, they often pose extra 
danger because of the longer duration of the events and the freeway 
environment where they often occur which may include evasive action by 
surrounding vehicles, therefore exposing more people to crash risk.
    In any case, it appears that stuck or trapped accelerator pedals 
present a serious safety problem and occur frequently enough to warrant 
regulatory action, even if accurate quantification of the problem is 
not possible at the present time.

VIII. Cost, Lead Time and Other Issues

A. Cost of the Proposed BTO Requirement

    We expect the cost of a brake-throttle override requirement for 
light vehicles to be close to zero for the following reasons. As of 
model year 2012, all but two light vehicle manufacturers have 
incorporated brake-throttle override in the ETC-equipped vehicle models 
that they produce for sale in the U.S. This is based on manufacturer-
supplied information that NHTSA receives as part of our annual safety 
compliance testing program. There are a few specific ETC-equipped 
models currently without BTO because they are at the end of their 
product design cycle and which either will be discontinued or will be 
equipped with BTO in the next design cycle, prior to the effective date 
of any final rule which results from this proposal.
    The proposed BTO regulation would set minimum requirements for 
existing as well as future light vehicle BTO systems. Based on our 
experience with them, existing systems will meet the proposed standard 
without modification. However, if some systems do require changes to 
meet the proposed standard, we believe the changes would be minimal.
    Because of the nearly 100 percent market penetration of the 
technology, the fact that most if not all systems already would meet 
the rule, and given that a final rule would not take effect for at 
least one or two years from the date of today's notice, we expect that 
manufacturer design, validation, and implementation costs attributable 
to the proposed brake-throttle override requirement for light vehicles 
would be close to zero.
    Compliance testing costs also are expected to be low since the 
proposed test procedure is nearly identical to existing brake 
performance test procedures and could be conducted along with existing 
brake performance tests.

B. Proposed Lead Time and Phase-In

    As discussed in Section V, we believe that current vehicles should 
be able to comply with the ACS disconnection requirements in this 
proposal without significant lead time because the updated procedures 
in this proposal do not change the basic return-to-idle requirement 
that has applied to motor vehicles for as long as the current standard 
has been in effect. We are proposing the following lead time for 
compliance with the disconnection requirements in this proposal as 
     Each vehicle shall comply within one year from the next 
September 1 following the date of publication of the final rule.

We are not proposing a phase-in period for the disconnection 
requirements because the proposed rule codifies the positions taken by 
the agency on those requirements that have been promulgated in 
interpretation letters available for a number of years to industry and 
the public. Also, our compliance testing of vehicles with ETC has not 
demonstrated significant compliance issues to date.

    We are proposing that lead time for compliance with the new brake-
throttle override requirements should be as follows:
     Each vehicle subject to the requirements shall comply 
within two years from the next September 1 of the date of publication 
of the final rule.

For example, if a final rule were published on October 1, 2012, the 
disconnection requirements in the final rule would take effect on 
September 1, 2013, and the brake-throttle override requirements would 
take effect on September 1, 2014. We believe that this would give 
vehicle manufacturers ample time to implement the new requirements at 
minimal cost.

    For the brake-throttle override requirements, we believe a phase-in 
is unnecessary because a significant portion of new vehicles already 
are either equipped with a BTO system or will be by the coming model 
    We request comment on the proposed lead time, including specific 
safety issues or cost and production issues that might influence the 
effective date of the rule.

C. Vehicles Over 10,000 lb GVWR

    In addition to covering light vehicles, FMVSS No. 124 also applies 
to heavy vehicles, i.e., trucks and buses. Many heavy trucks are 
diesel-powered. For

[[Page 22657]]

throttle system disconnection testing on those vehicles, the fuel rate 
compliance option would be applicable. The creep speed procedure on a 
dynamometer or test track would be an option also. However, since heavy 
truck powertrains and chassis often are produced separately by 
different manufacturers, a given powertrain might have to be certified 
for several different chassis. Responsibility for certification 
(assuming it is a multi-stage manufacturing situation) typically would 
fall to the chassis manufacturer.
    For heavy vehicles, a brake-throttle override requirement may or 
may not be necessary. Trucks and buses already are subject to 
compliance with FMVSS No. 105, Hydraulic and electric brake systems and 
FMVSS No. 121, Air brake systems, so performance tests based on braking 
distance are practicable. In addition, NHTSA's complaint and crash data 
reports do not indicate a trapped pedal problem in heavy vehicles.
    Furthermore, trucks and buses often operate at full throttle during 
normal driving, and the acceleration rate of trucks and buses is 
significantly lower than for light vehicles. Additionally, most trucks 
have manual transmissions for which the clutch functions as an 
available countermeasure in the case of a stuck throttle in a truck.
    Since there is no apparent safety need for brake-throttle override 
systems to apply to heavy vehicles, we are proposing that the brake-
throttle override requirement would apply only to passenger cars, 
multipurpose passenger vehicles, trucks, and buses with GVWRs of 10,000 
pounds or less. However, we seek comment on this issue, specifically 
any data related to pedal entrapment or similar issues where BTO might 
be an effective safeguard.

D. Manual Transmission Vehicles

    In the proposed brake-throttle override system regulation, we have 
not made any distinction for vehicles with GVWRs of 10,000 pounds or 
less equipped with manual transmissions. There are cogent reasons why 
manual transmission-equipped vehicles might be less susceptible to 
crashes resulting from trapped pedals. Primarily, these vehicles have a 
clutch pedal which disengages the engine from the drive-wheels. This 
provides an expedient countermeasure for a driver in the event of a 
trapped accelerator pedal. Furthermore, clutch operation is not 
influenced by a stuck throttle the way that brake operation may be.
    Compared to vehicles with automatic transmissions, pedal placement 
in a manual transmission vehicle may be different and the brake pedal 
typically is smaller. We do not know if these factors influence trapped 
pedal incidents, either positively or negatively.
    NHTSA invites comments on this issue. If comments include 
sufficient justification for excluding manual transmission vehicles 
from the BTO requirements, and we are convinced that there will be no 
safety-related consequences, we will consider adopting that exclusion. 
Otherwise, we would not have any basis for excluding vehicles from the 
brake-throttle override system requirements based on their having a 
manual transmission.

E. Proposed New Title for FMVSS No. 124

    To reflect the addition of a Brake-Throttle Override requirement, 
we are proposing that the title of FMVSS No. 124 be changed from 
``Accelerator control systems'' to ``Accelerator control and brake-
throttle override systems.'' We invite comment on this proposed change.

IX. Rulemaking Analyses and Notices

A. Executive Orders 12866 and 13563 and DOT Regulatory Policies and 

    The agency has considered the impact of this rulemaking action 
under Executive Orders 12866 and 13563 (January 18, 2011, ``Improving 
Regulation and Regulatory Review'') the Department of Transportation's 
regulatory policies and procedures (44 FR 11034; February 26, 1979). 
OMB has advised us that this NPRM is not significant. This action was 
not reviewed by the Office of Management and Budget under these 
executive orders. It is not considered to be significant under the 
Department's Regulatory Policies and Procedures.\[1]\

    \[1]\ Department of Transportation, Adoption of Regulatory 
Policies and Procedures, 44 FR 11034 (Feb. 26, 1979).

    This NPRM includes the following proposed changes to FMVSS No. 124: 
Adds language so the Standard explicitly applies to ETC systems; 
includes test procedures for hybrids and other vehicles whose 
propulsion is not governed by throttling of combustion air intake; and 
adds a new requirement for a brake-throttle override system. We believe 
that the cost of implementing this proposal, if adopted, would be 
relatively small. Given the interpretations issued by NHTSA, 
manufacturers should have been aware for a long time of the 
applicability of FMVSS No. 124 to ETC-equipped vehicles. Since this 
proposal does not change the scope of the ACS disconnection 
requirements and only defines specific test procedures for ETC systems, 
all vehicles should be able to comply without costly re-design. Also, 
since this proposal allows new alternative methods of compliance for 
ACS disconnections, vehicles should not have significant compliance 
    There would likely be costs associated with certification testing. 
Those costs might vary somewhat depending on which procedure a 
manufacturer selects, but they should be similar to the costs of 
certifying to the current standard. In the case of the powertrain 
output (i.e., creep speed) test option, we expect the cost would be 
comparable to that for a single test run conducted for EPA emission or 
fuel economy purposes in a dynamometer facility or on a test track. 
These are tests that vehicle manufacturers conduct routinely either in 
their own facilities or through a commercially available source.
    For Brake-Throttle-Override systems, we believe the cost of the 
rule would be minimal because manufacturers already are incorporating 
BTO in their light vehicle fleets, and those systems are likely to meet 
the new safety requirement without modification. This would minimize 
any costs attributable to a NHTSA rule. There would be compliance 
testing costs.

B. Regulatory Flexibility Act

    Pursuant to the Regulatory Flexibility Act (5 U.S.C. 601 et seq., 
as amended by the Small Business Regulatory Enforcement Fairness Act 
(SBREFA) of 1996), whenever an agency is required to publish a notice 
of rulemaking for any proposed or final rule, it must prepare and make 
available for public comment a regulatory flexibility analysis that 
describes the effect of the rule on small entities (i.e., small 
businesses, small organizations, and small governmental jurisdictions). 
The Small Business Administration's regulations at 13 CFR Part 121 
define a small business, in part, as a business entity ``which operates 
primarily within the United States.'' (13 CFR 121.105(a)). No 
regulatory flexibility analysis is required if the head of an agency 
certifies that the rule will not have a significant economic impact on 
a substantial number of small entities. The SBREFA amended the 
Regulatory Flexibility Act to require Federal agencies to provide a 
statement of the factual basis for certifying that a rule will not have 
a significant economic impact on a substantial number of small 
    NHTSA has considered the effects of this rulemaking action under 

[[Page 22658]]

Regulatory Flexibility Act. According to 13 CFR 121.201, the Small 
Business Administration's size standards regulations used to define 
small business concerns, manufacturers of passenger vehicles would fall 
under North American Industry Classification System (NAICS) No. 336111, 
Automobile Manufacturing, which has a size standard of 1,000 employees 
or fewer. Using the size standard of 1,000 employees or fewer, NHTSA 
estimates that there are fewer than 20 small business manufacturers of 
passenger vehicles subject to the proposed requirements.
    The Head of the Agency hereby certifies that this proposed rule 
would not have a significant economic impact on a substantial number of 
small entities. The basis for this certification is that if made final, 
none of the proposed changes will require the addition of new systems 
or equipment on existing vehicles that manufacturers are not already 
putting on vehicles (i.e., brake-override systems), and costs 
associated with the proposal will be minimal for all manufacturers, 
including small businesses.

C. Executive Order 13132 (Federalism)

    NHTSA has examined today's proposal pursuant to Executive Order 
13132 (64 FR 43255; Aug. 10, 1999) and concluded that no additional 
consultation with States, local governments, or their representatives 
is mandated beyond the rulemaking process. The agency has concluded 
that the proposal would not have sufficient federalism implications to 
warrant consultation with State and local officials or the preparation 
of a federalism summary impact statement. The proposal would not have 
``substantial direct effects on the States, on the relationship between 
the national government and the States, or on the distribution of power 
and responsibilities among the various levels of government.''
    NHTSA rules can have preemptive effect in two ways. First, the 
National Traffic and Motor Vehicle Safety Act contains an express 
preemption provision:

    When a motor vehicle safety standard is in effect under this 
chapter, a State or a political subdivision of a State may prescribe 
or continue in effect a standard applicable to the same aspect of 
performance of a motor vehicle or motor vehicle equipment only if 
the standard is identical to the standard prescribed under this 

49 U.S.C. 30103(b)(1). It is this statutory command that preempts any 
non-identical State legislative and administrative law \22\ addressing 
the same aspect of performance.

    \22\ The issue of potential preemption of state tort law is 
addressed in the immediately following paragraph discussing implied 

    The express preemption provision described above is subject to a 
savings clause under which ``[c]ompliance with a motor vehicle safety 
standard prescribed under this chapter does not exempt a person from 
liability at common law.'' 49 U.S.C. 30103(e). Pursuant to this 
provision, State common law tort causes of action against motor vehicle 
manufacturers that might otherwise be preempted by the express 
preemption provision are generally preserved. However, the Supreme 
Court has recognized the possibility, in some instances, of implied 
preemption of State common law tort causes of action by virtue of 
NHTSA's rules--even if not expressly preempted.
    This second way that NHTSA rules can preempt is dependent upon the 
existence of an actual conflict between an FMVSS and the higher 
standard that would effectively be imposed on motor vehicle 
manufacturers if someone obtained a State common law tort judgment 
against the manufacturer--notwithstanding the manufacturer's compliance 
with the NHTSA standard. Because most NHTSA standards established by an 
FMVSS are minimum standards, a State common law tort cause of action 
that seeks to impose a higher standard on motor vehicle manufacturers 
will generally not be preempted. However, if and when such a conflict 
does exist--for example, when the standard at issue is both a minimum 
and a maximum standard--the State common law tort cause of action is 
impliedly preempted. See Geier v. American Honda Motor Co., 529 U.S. 
861 (2000).
    Pursuant to Executive Order 13132, NHTSA has considered whether 
this rule could or should preempt State common law causes of action. 
The agency's ability to announce its conclusion regarding the 
preemptive effect of one of its rules reduces the likelihood that 
preemption will be an issue in any subsequent tort litigation.
    To this end, the agency has examined the nature (e.g., the language 
and structure of the regulatory text) and objectives of today's rule. 
NHTSA does not intend that this rule preempt state tort law that would 
effectively impose a higher standard on motor vehicle manufacturers 
than that established by today's rule. Establishment of a higher 
standard by means of State tort law would not conflict with the 
proposal announced here. Without any conflict, there could not be any 
implied preemption of a State common law tort cause of action.

D. National Environmental Policy Act

    NHTSA has analyzed this NPRM for the purposes of the National 
Environmental Policy Act. The agency has determined that implementation 
of this action would not have any significant impact on the quality of 
the human environment.

E. Paperwork Reduction Act

    Before a Federal agency can collect certain information from the 
public, it must receive approval from the Office of Management and 
Budget (OMB). Under the Paperwork Reduction Act of 1995, a person is 
not required to respond to a collection of information by a Federal 
agency unless the collection displays a valid OMB control number. NHTSA 
has carefully examined this notice of proposed rulemaking and has 
determined that there are no Paperwork Reduction Act consequences on 
motor vehicle manufacturers or any other members of the public if this 
NPRM is made final.

F. National Technology Transfer and Advancement Act

    Under the National Technology Transfer and Advancement Act of 1995 
(NTTAA) (Pub. L. 104-113), ``all Federal agencies and departments shall 
use technical standards that are developed or adopted by voluntary 
consensus standards bodies, using such technical standards as a means 
to carry out policy objectives or activities determined by the agencies 
and departments.'' In today's NPRM, NHTSA proposes to incorporate by 
reference, in whole or in part, two voluntary consensus standards 
developed by the Society of Automotive Engineers (SAE): SAE J2264 (APR 
95) ``Chassis Dynamometer Simulation of Road Load Using Coastdown 
Techniques'' and in SAE J1263 (JAN2009), ``Road Load Measurement and 
Dynamometer Simulation Using Coastdown Techniques,'' the following test 
conditions: S7.1, ``Ambient Temperature''; S7.2 ``Fog,'' S7.3 
``Winds,'' and S7.4 ``Road Conditions.''

G. Executive Order 12988

    With respect to the review of the promulgation of a new regulation, 
section 3(b) of Executive Order 12988, ``Civil Justice Reform'' (61 FR 
4729, February 7, 1996) requires that Executive agencies make every 
reasonable effort to ensure that the regulation: (1) Clearly specifies 
the preemptive effect; (2) clearly specifies

[[Page 22659]]

the effect on existing Federal law or regulation; (3) provides a clear 
legal standard for affected conduct, while promoting simplification and 
burden reduction; (4) clearly specifies the retroactive effect, if any; 
(5) adequately defines key terms; and (6) addresses other important 
issues affecting clarity and general draftsmanship under any guidelines 
issued by the Attorney General. This document is consistent with that 
    Pursuant to this Order, NHTSA notes as follows. The issue of 
preemption is discussed above in connection with E.O. 13132. NHTSA 
notes further that there is no requirement that individuals submit a 
petition for reconsideration or pursue other administrative proceeding 
before they may file suit in court.

H. Unfunded Mandates Reform Act

    The Unfunded Mandates Reform Act of 1995 requires agencies to 
prepare a written assessment of the costs, benefits and other effects 
of proposed or final rules that include a Federal mandate likely to 
result in the expenditure by State, local or tribal governments, in the 
aggregate, or by the private sector, of more than $100 million annually 
(adjusted for inflation with base year of 1995). This NPRM, if made 
final, would not result in expenditures by State, local or tribal 
governments, in the aggregate, or by the private sector in excess of 
$100 million annually.

I. Executive Order 13045

    Executive Order 13045 (62 FR 19885, April 23, 1997) applies to any 
rule that: (1) Is determined to be ``economically significant'' as 
defined under E.O. 12866, and (2) concerns an environmental, health, or 
safety risk that NHTSA has reason to believe may have a 
disproportionate effect on children. This rulemaking is not subject to 
the Executive Order because it is not economically significant as 
defined in E.O. 12866. However, since this NPRM, if made final, would 
require an updated ACS on passenger cars, multipurpose passenger 
vehicles, trucks and buses, and would require a brake-throttle override 
system on passenger cars, multipurpose passenger vehicles, trucks and 
buses with a GVWR of 10,000 pounds or less, it should have a beneficial 
safety effect on children riding in such vehicles.

J. Executive Order 13211

    Executive Order 13211 (66 FR 28355, May 18, 2001) applies to any 
rulemaking that: (1) Is determined to be economically significant as 
defined under E.O. 12866, and is likely to have a significantly adverse 
effect on the supply of, distribution of, or use of energy; or (2) that 
is designated by the Administrator of the Office of Information and 
Regulatory Affairs as a significant energy action. This rulemaking is 
not subject to E.O. 13211.

K. Plain Language

    The Plain Writing Act of 2010 (Pub. L. 111-274) and Executive Order 
12866 require each agency to write all rules in plain language. 
Application of the principles of plain language includes consideration 
of the following questions:
     Have we organized the material to suit the public's needs?
     Are the requirements in the rule clearly stated?
     Does the rule contain technical language or jargon that is 
not clear?
     Would a different format (grouping and order of sections, 
use of headings, paragraphing) make the rule easier to understand?
     Would more (but shorter) sections be better?
     Could we improve clarity by adding tables, lists, or 
     What else could we do to make the rule easier to 
    If you have any responses to these questions, please include them 
in your comments on this proposal.

L. Regulation Identifier Number (RIN)

    The Department of Transportation assigns a regulation identifier 
number (RIN) to each regulatory action listed in the Unified Agenda of 
Federal Regulations. The Regulatory Information Service Center 
publishes the Unified Agenda in April and October of each year. You may 
use the RIN contained in the heading at the beginning of this document 
to find this action in the Unified Agenda.

M. Privacy Act

    Anyone is able to search the electronic form of all comments 
received into any of our dockets by the name of the individual 
submitting the comment (or signing the comment, if submitted on behalf 
of an association, business, labor union, etc.). You may review DOT's 
complete Privacy Act Statement in the Federal Register published on 
April 11, 2000 (Volume 65, Number 70; Pages 19477-78).

X. Public Participation

How do I prepare and submit comments?

    Your comments must be written and in English. To ensure that your 
comments are correctly filed in the Docket, please include the docket 
number of this document in your comments.
    Your comments must not be more than 15 pages long. (49 CFR 553.21.) 
We established this limit to encourage you to write your primary 
comments in a concise fashion. However, you may attach necessary 
additional documents to your comments. There is no limit on the length 
of the attachments.
    Comments may also be submitted to the docket electronically by 
logging onto the Docket Management System Web site at http://www.regulations.gov. Follow the online instructions for submitting 
    Please note that pursuant to the Data Quality Act, in order for 
substantive data to be relied upon and used by the agency, it must meet 
the information quality standards set forth in the OMB and DOT Data 
Quality Act guidelines. Accordingly, we encourage you to consult the 
guidelines in preparing your comments. OMB's guidelines may be accessed 
at http://www.whitehouse.gov/omb/fedreg_reproducible.

How can I be sure that my comments were received?

    If you wish Docket Management to notify you upon its receipt of 
your comments, enclose a self-addressed, stamped postcard in the 
envelope containing your comments. Upon receiving your comments, Docket 
Management will return the postcard by mail.

How do I submit confidential business information?

    If you wish to submit any information under a claim of 
confidentiality, you should submit three copies of your complete 
submission, including the information you claim to be confidential 
business information, to the Chief Counsel, NHTSA, at the address given 
above under FOR FURTHER INFORMATION CONTACT. In addition, you should 
submit a copy, from which you have deleted the claimed confidential 
business information, to the docket at the address given above under 
ADDRESSES. When you send a comment containing information claimed to be 
confidential business information, you should include a cover letter 
setting forth the information specified in our confidential business 
information regulation. (49 CFR Part 512.)

Will the agency consider late comments?

    We will consider all comments received before the close of business 
on the comment closing date indicated above under DATES. To the extent

[[Page 22660]]

possible, we will also consider comments that the docket receives after 
that date. If the docket receives a comment too late for us to consider 
in developing a final rule (assuming that one is issued), we will 
consider that comment as an informal suggestion for future rulemaking 

How can I read the comments submitted by other people?

    You may read the comments received by the docket at the address 
given above under ADDRESSES. The hours of the docket are indicated 
above in the same location. You may also see the comments on the 
Internet. To read the comments on the Internet, go to http://www.regulations.gov. Follow the online instructions for accessing the 
    Please note that even after the comment closing date, we will 
continue to file relevant information in the docket as it becomes 
available. Further, some people may submit late comments. Accordingly, 
we recommend that you periodically check the Docket for new material. 
You can arrange with the docket to be notified when others file 
comments in the docket. See http://www.regulations.gov for more 

List of Subjects in 49 CFR Part 571

    Imports, Motor vehicle safety, Motor vehicles, and Tires.

Proposed Regulatory Text for FMVSS No. 124

    In consideration of the foregoing, NHTSA proposes to amend 49 CFR 
Part 571 as set forth below.


    1. The authority citation for Part 571 continues to read as 

    Authority: 49 U.S.C. 322, 30111, 30115, 30117 and 30166; 
delegation of authority at 49 CFR 1.50.

    2. Section 571.5 is amended by adding paragraphs (k)(50) and 
(k)(51) to read as follows:

Sec.  571.5  Matter incorporated by reference.

* * * * *
    (k) * * *
    (50) SAE 1263 (JAN2009) ``Road Load Measurement and Dynamometer 
Simulation Using Coastdown Techniques,'' Sections S7.1 ``Ambient 
Temperature,'' S7.2 ``Fog,'' S7.3 ``Winds,'' and S7.4 ``Road 
    (51) SAE J2264 (APR 1995) ``Chassis Dynamometer Simulation of Road 
Load Using Coastdown Techniques.''
* * * * *
    3. Section 571.124 is revised to read as follows:

Sec.  571.124  Standard No. 124; Accelerator control and brake-throttle 
override systems.

    S1. Scope. This standard establishes requirements for each engine, 
electric motor, and other motive power source connected to a vehicle's 
drive wheels to return to idle, within a specified time and a specified 
tolerance, whenever actuating force on the driver-operated accelerator 
control is removed and whenever there is a severance or disconnection 
in the accelerator control system. This standard also establishes 
requirements for brake-actuated throttle override systems.
    S2. Purpose. The purpose of this standard is to reduce deaths and 
injuries resulting from uncontrolled vehicle propulsion caused by 
malfunctions or disconnections in accelerator control systems and from 
conflicting inputs to the brake and accelerator controls in a vehicle.
    S3. Application. This standard applies to passenger cars, 
multipurpose passenger vehicles, trucks, and buses. Section S6.6 does 
not apply to vehicles having a GVWR greater than 10,000 lb (4545 kg), 
or to vehicles without Electronic Throttle Control.
    S4. Definitions.
    Accelerator control system means all vehicle components, including 
both mechanical and electrical/electronic components and modules, that 
operate a vehicle's throttle in response to movement of the driver-
operated accelerator control and that, upon removal of actuating force 
on the driver-operated control, return both the throttle and the 
driver-operated control to their idle or rest positions. For the 
purposes of this standard, an electronic control module is considered a 
single component, and the external wiring and connections of each 
module to other accelerator control system components and to other 
vehicle components including power and ground connections are subject 
to severance or disconnection.
    Air intake rate means the rate at which combustion air is supplied 
to an engine.
    Air-throttled engine means an internal combustion engine in which 
output power is controlled primarily through regulation of the air 
intake rate.
    Ambient temperature means the temperature of air surrounding a test 
vehicle measured at a sufficient distance to not be significantly 
affected by heat from the test vehicle.
    Coastdown means vehicle deceleration which occurs when there is no 
input to either the brake or accelerator pedals.
    Creep speed means the maximum terminal speed that can be achieved 
when a vehicle in a lightly loaded condition, starting from a 
standstill or any speed of which the vehicle is capable, is driven in 
any gear with no input to its driver-operated accelerator control.
    Driver-operated accelerator control means any device on a vehicle, 
such as an accelerator pedal, that a driver uses to modulate engine or 
motor power, but not including cruise control, locking hand throttles, 
or any engine or motor control not intended for regulating vehicle 
    Electric power delivery means a power computation (such as wattage) 
derived from the current and voltage input to an electric motor that 
drives a vehicle.
    Electronic throttle control means an accelerator control system in 
which movement of the driver-operated control is translated into 
throttle actuation, at least in part by electronic, instead of 
mechanical, means.
    Engine or motor means any source of motive power in a vehicle, 
including internal combustion engines and electric motors, connected to 
the drive wheels and capable of propelling the vehicle.
    Fuel delivery rate means the net rate of fuel use (supply minus 
return) in an engine.
    Fuel metering device means the internal parts of a carburetor, fuel 
injector, fuel distributor, or fuel injection pump, and the internal 
elements of electronic modules in the accelerator control system such 
as circuit boards and discrete electrical components contained inside 
an engine control module, which adjust engine or motor operating 
variables such as fuel-air ratio and ignition timing.
    Fuel-throttled engine means an internal combustion engine in which 
output power is controlled primarily through regulation of fuel 
delivery rate.
    Idle or idle state means the normal running condition of a 
vehicle's engine or motor with no faults or malfunctions affecting 
engine or motor output when there is no input to the driver-operated 
accelerator control.
    Idle state conditions are conditions which influence idle state 
during normal operation of a vehicle, including but not limited to 
engine temperature, air-conditioner load, emission control state, and 
the use of speed setting devices such as cruise control.
    Idle state indicant means a vehicle operating parameter which 
varies directly with engine or motor output, including: throttle 
position, fuel delivery rate, air intake rate, electric power delivery, 
and creep speed.
    Throttle means the component of an accelerator control system 
which, in

[[Page 22661]]

response to movement of the driver-operated accelerator control, 
modulates vehicle propulsion by varying throttle position, fuel 
delivery rate, air intake rate, electric power delivery, or other means 
by which powertrain output is regulated.
    S5. Requirements. Each vehicle shall meet the requirements of S5.1 
through S5.3 when tested in accordance with applicable procedures in 
S6, at any ambient temperature between minus 40 and plus 50 degrees 
Celsius and after 12 hours of conditioning at any temperature within 
that range unless otherwise specified, and with its engine or motor 
running under any load condition and at any speed of which the engine 
or motor is capable.
    S5.1 Normal Operation. The throttle shall return to idle within the 
time limit specified in S5.3 whenever the driver-operated accelerator 
control is released from any position when the vehicle is tested in 
accordance with S6.3.
    S5.2 Fail-safe Operation. Each vehicle shall meet S5.2.1 or S5.2.2. 
A fuel metering device is not subject to disconnection or severance 
under this test procedure.
    S5.2.1 In the event of a disconnection or severance at a single 
point of any one component of the accelerator control system, including 
disconnection or severance of an electrical component that results in 
an open circuit or a short circuit to ground, but not a disconnection 
or severance inside of an electronic module, the throttle shall return 
to or below idle plus a tolerance of 50 percent, within the time limit 
specified in S5.3 after release of the driver-operated accelerator 
control from any position, when tested in accordance with S6.4; or
    S5.2.2 When tested in accordance with S6.5, each vehicle's maximum 
creep speed shall be no greater than 50 km/h (31 mph), and the vehicle 
shall decelerate continuously from any initial speed greater than 50 
km/h of which the vehicle is capable until its speed is reduced to 50 
km/h or lower, and the time required to coast down to 50 km/h shall not 
exceed the time required to coast down to 50 km/h from the same speed 
in neutral gear without faults in the accelerator control system.
    S5.3 Response Time. When tested in accordance with S6.3 and S6.4, 
the maximum time to return to idle as indicated by the throttle 
position or other selected idle state indicant shall be
    (a) Not greater than 1 second for vehicles of 4536 kilograms 
(10,000 pounds) or less gross vehicle weight rating (GVWR),
    (b) Not greater than 2 seconds for vehicles of more than 4536 
kilograms (10,000 pounds) GVWR, and
    (c) Not greater than 3 seconds for vehicles, regardless of GVWR, 
that are exposed to ambient air at minus 18 to minus 40 degrees Celsius 
during a test or any portion of the 12-hour conditioning period.
    S5.4 Brake-Throttle Override.
    S5.4.1 Each motor vehicle under 10,000 lb GVWR having electronic 
throttle control shall meet the performance requirement of S6.6 and 
shall be equipped with a throttle-override system that is engaged by 
application of the vehicle's service brake and that meets the following 
    (a) The system shall consist of hardware and/or software components 
on the vehicle which have the capability of identifying and reacting to 
conflicts between accelerator pedal and brake pedal inputs;
    (b) At vehicle speeds greater than 16 km/h (10 mph), when a 
conflict exists between the vehicle's accelerator and brake pedals, the 
override system must engage and must substantially reduce propulsive 
force delivered to the driving wheels to a controllable level by means 
of a change in throttle opening, fuel delivery rate, air intake rate, 
electric power delivery, or an equivalent means;
    (c) Once engaged, the override must remain engaged at any speed as 
long as brake pedal application is maintained at or above the force 
level or travel which initially engaged the override, and as long as 
accelerator pedal input is in conflict with the brake application.
    S5.4.2 When tested in accordance with the brake-throttle override 
performance test in S6.6, a vehicle is deemed to comply if at least one 
of the six stops is made within the prescribed distance. However, in 
all of the six stops, the brake-throttle override must engage if the 
system identifies a conflict between the accelerator pedal and brake.
    S5.4.3 If a means is provided for the vehicle operator to turn off 
the brake-throttle override system--
    (a) There must be an illuminated alert or message that remains in 
view of the driver as long as the system is turned off and the vehicle 
ignition is on, and
    (b) The system must default to an active state whenever the vehicle 
ignition is started.
    S6. Test Procedures.
    S6.1 Irrevocable Selection. The manufacturer shall select one of 
the following criteria upon which it bases its certification to the 
requirements in section S5.1 and S5.2 in this standard: throttle 
position, fuel delivery rate, air intake rate, electric power delivery, 
or creep speed/coastdown performance. This selection is irrevocable and 
shall be made prior to or at the time of certification of the vehicle 
pursuant to 49 CFR Part 567, ``Certification.''
    S6.2 General. For the test procedures in sections S6.3 and S6.4, 
the ``baseline'' value is the value of the selected idle state indicant 
measured for an engine or motor operating at idle without accelerator 
control system faults under the conditions that exist at the beginning 
of a test and which are held constant during the test.
    (a) For idle state conditions that provide a means of driver 
control, for example air-conditioner setting, the selected setting for 
testing may be any point within the control range, including ``off.''
    (b) The engine or motor is operated for not less than 5 minutes to 
stabilize the idle state prior to testing.
    (c) Vehicles are conditioned and tested at any ambient temperature 
between minus 40 and plus 50 degrees Celsius, except as specified for 
creep speed and coastdown test procedures in S6.5.
    (d) The time to return to idle in S6.4 is measured first from the 
instant that a severance or disconnection occurs and then, if 
necessary, from the instant of release of the driver-operated 
accelerator control.
    S6.3 Test Procedure for Evaluating Return-to-Idle in Normal 
    S6.3.1 Condition the test vehicle to a selected ambient temperature 
for up to 12 hours.
    S6.3.2 Start the vehicle, set controls such as for the air-
conditioner, and operate the engine for not less than 5 minutes.
    S6.3.3 Measure the baseline value of one of the following idle 
state indicants identified by the vehicle manufacturer for the test 
vehicle: throttle position, fuel delivery rate, air intake rate, or 
electric power delivery.
    S6.3.4 Set engine speed and powertrain loading condition by 
shifting the transmission to neutral or any gear and moving the driver-
operated accelerator control to any position, with or without 
resistance applied to the vehicle's drive wheels.
    S6.3.5 After at least 3 seconds, release the driver-operated 
accelerator control.
    S6.3.6 Verify that the measured idle state indicant returns to or 
below its baseline value determined in S6.3.3 following release of the 
driver-operated accelerator control within the response time specified 
in S5.3.

[[Page 22662]]

    6.4 Test Procedure for Evaluating Return-to-Idle Following a 
Disconnection or Severance
    6.4.1 Condition the test vehicle to a selected ambient temperature 
for up to 12 hours.
    S6.4.2 Start the vehicle, set controls such as for air-
conditioning, and operate the engine for not less than 5 minutes.
    S6.4.3 Measure the baseline idle value of one of the following idle 
state indicants identified by the vehicle manufacturer for the test 
vehicle: throttle position, fuel delivery rate, air intake rate, or 
electric power delivery.
    S6.4.4 Set engine speed and powertrain loading condition by 
shifting the transmission to neutral or any gear and moving the driver-
operated accelerator control to any position, with or without 
resistance applied to the vehicle's drive wheels.
    S6.4.5 While continuing to measure the idle state indicant, 
disconnect one component of the accelerator control system by removing 
one connector or severing a wiring harness or individual wire, leaving 
the disconnected or severed component in either an open circuit 
condition or shorted to ground.
    S6.4.6 If there is no change in the idle state indicant after at 
least 3 seconds, release the driver-operated accelerator control.
    S6.4.7 Verify that, following either S6.4.5 or S6.4.6, the idle 
state indicant returns to and remains at or below a value that is no 
more than 50 percent greater than its baseline value as measured in 
S6.4.3, within the response time specified in S5.3.
    S6.5 Alternative Procedure for Evaluating Return-to-Idle Following 
a Disconnection or Severance, Using Creep Speed and Coastdown
    S6.5.1 This test procedure measures creep speed and coastdown time 
on a chassis (wheel-driven) dynamometer configured to simulate the 
correct road load as a function of speed for the test vehicle as 
determined in accordance with SAE J2264 (APR 95), ``Chassis Dynamometer 
Simulation of Road Load Using Coastdown Techniques.'' (Incorporated by 
reference, see Sec.  571.5.) This test procedure also may be performed 
on a straight road course consisting of dry, smooth, unbroken asphalt 
or concrete pavement with a continuous grade of not more than 0.5 
percent in any direction.
    S6.5.2 The test vehicle is lightly loaded (driver-only with no 
cargo and fuel tank level between one-quarter and full.) Tires are set 
at cold inflation pressures provided on the vehicle placard and/or the 
tire inflation label, and all vehicle windows are fully closed. For 
track tests, ambient conditions are as specified in SAE J1263 (JAN 
2009), ``Road Load Measurement and Dynamometer Simulation Using 
Countdown Techniques'' in section 7, ``Test Conditions'' at S7.1 
``Ambient Temperatures'', S7.2 ``Fog,'' S7.3 ``Winds,'' and S7.4 ``Road 
Conditions'' (incorporated by reference, see Sec.  571.5).
    S6.5.3 Time intervals measured in S6.5.5 and S6.5.6 begin at the 
instant that a disconnection or severance is induced in the accelerator 
control system, or from the instant that the accelerator pedal is 
released or the transmission is shifted to neutral, as applicable, 
depending on which of those actions initiates a vehicle response. Test 
vehicle speed versus time are recorded continuously during test runs.
    S6.5.4 Start up the test vehicle, set accessory controls such as 
for air-conditioning, and operate the vehicle for not less than 5 
    S6.5.5 Creep Speed Measurement Procedure
    (a) With the vehicle's drive wheels on the dynamometer roller(s) or 
with the vehicle positioned on the road test course, place the 
transmission selector in the ``drive'' position. For manual 
transmissions, select the highest gear (lowest numerical gear ratio) 
which allows the vehicle to coast without stalling if the clutch is 
gradually released when there is no input to the accelerator pedal.
    (b) With the vehicle operating at idle or at any target speed up to 
50 km/h (31 mph), simultaneously release the accelerator pedal (if 
applied) and disconnect one component of the accelerator control system 
by removing one connector or severing a wiring harness or individual 
wire, leaving the disconnected or severed component in either an open 
circuit condition or shorted to ground.
    (c) Note the speed of the test vehicle at 90 seconds after the 
disconnection and verify that it does not exceed 50 km/h.
    S6.5.6 Coastdown Time Measurement Procedure
    (a) With the vehicle's drive wheels on the dynamometer roller(s) or 
with the vehicle positioned on the road test course, place the 
transmission selector in the ``drive'' position and drive the vehicle 
up to any selected target speed greater than 50 km/h. For manual 
transmissions, select any gear appropriate for the selected target 
    (b) At the target speed, release the accelerator pedal and 
simultaneously shift the vehicle into neutral. Allow the vehicle to 
coast without any brake input.
    (c) Verify that the vehicle decelerates to or below 50 km/h and 
record the elapsed time needed for the vehicle to reach 50 km/h.
    (d) Repeat the step in S6.5.6(a) and, at the same target speed, 
simultaneously release the accelerator pedal and disconnect one 
component of the accelerator control system by removing one connector 
or severing a wiring harness or individual wire, leaving the 
disconnected or severed component in either an open circuit condition 
or shorted to ground.
    (e) Record the elapsed time needed for the vehicle to decelerate to 
50 km/h, and verify that it does not exceed the elapsed time in the 
step in S6.5.6(c).
    S6.6 Performance Test for Brake-Throttle Override Systems.
    Measure vehicle stopping distance with the test vehicle's 
accelerator pedal applied as specified in the following procedure:
    S6.6.1 Select a target speed which is greater than or equal to 30 
km/h and less than or equal to 160 km/h and which, if greater than 100 
km/h, does not exceed 80 percent of the test vehicle's maximum speed. 
``Maximum speed'' is used as defined in section S4 of 49 CFR 571.135, 
``Light Vehicle Brake Systems,'' (FMVSS No. 135).
    S6.6.2 Conduct stopping distance measurements in accordance with 
the general procedures and test conditions specified in S6 of FMVSS No. 
135, and as follows:
    (a) Accelerate the test vehicle and, while still in gear, hold the 
accelerator pedal in any fixed position between 25 and 100 percent of 
the full range of pedal travel.
    (b) At the target speed, without releasing the accelerator pedal 
from the position as selected in S6.6.2(a), apply the service brake and 
bring the vehicle to a stop using a brake pedal force of not less than 
65N (14.6 lbs) and not more than 500N (112.4 lbs).;
    (c) Repeat six times for a total of six test runs at each target 
    S6.6.3 Verify that the stopping distance `S' (in meters) for each 
vehicle speed `V' (in km/h) is no more than 5 percent greater than the 
stopping distance specified in either S7.5.3(b) or S7.6.3 of FMVSS No. 
135 by meeting one of the following requirements:
    (a) For test speeds up to and including 100 km/h: S <= 1.05(0.10V + 
    (b) For test speeds greater than 100 km/h: S <= 1.05(0.10V + 

    Issued on: March 28, 2012.
Christopher J. Bonanti,
Associate Administrator for Rulemaking.
[FR Doc. 2012-9065 Filed 4-12-12; 11:15 am]