[Federal Register Volume 69, Number 217 (Wednesday, November 10, 2004)]
[Proposed Rules]
[Pages 65126-65127]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 04-24978]


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DEPARTMENT OF TRANSPORTATION

National Highway Traffic Safety Administration

49 CFR Part 571

[Docket No. NHTSA-2002-12845]
RIN 2127-AH71


Federal Motor Vehicle Safety Standards; Accelerator Control 
Systems

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

ACTION: Withdrawal of rulemaking.

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SUMMARY: In July 2002, NHTSA published an NPRM proposing to update 
Federal Motor Vehicle Safety Standard (FMVSS) No. 124, the agency's 
safety standard for vehicle accelerator control systems, to make 
explicit its applicability to new types of engines and throttle 
controls, particularly electronic ones. The proposal included a number 
of new test procedures to address different types of powertrain 
technology. One of those test procedures involved measurement of engine 
speed under realistic powertrain load conditions on a chassis 
dynamometer. That procedure was ``technology-neutral'' and was included 
to allow testing of vehicles that could not readily be tested by one of 
the other procedures included in the proposal that were technology 
specific.
    As discussed in this document, the agency is withdrawing the NPRM 
while it conducts further research on issues relating to chassis 
dynamometer-based test procedures for accelerator controls.

FOR FURTHER INFORMATION CONTACT: The following persons at the NHTSA, 
400 7th Street, SW., Washington, DC 20590.
    For non-legal issues, you may call Mr. Michael Pyne, Office of 
Crash Avoidance Standards (Telephone: 202-366-2720) (Fax: 202-366-
7002).
    For legal issues, you may call Ms. Dorothy Nakama, Office of Chief 
Counsel (Telephone: 202-366-2992) (Fax: 202-366-3820).

SUPPLEMENTARY INFORMATION: 

I. Background

    Federal Motor Vehicle Safety Standard (FMVSS) No. 124, Accelerator 
Control Systems, provides for safe control of engine power by a 
vehicle's driver-operated accelerator. For vehicles that are operating 
with their accelerator controls intact, FMVSS No. 124 requires the 
rapid return of the throttle to the idle position (within one second 
for light vehicles and two seconds for heavy vehicles) when the 
accelerator pedal is released. For vehicles that experience 
disconnections in the linkage between their accelerator pedals and 
throttling devices, FMVSS No. 124 requires return to idle in an equally 
rapid fashion. By virtue of FMVSS No. 124's requirements, drivers are 
ensured that releasing the accelerator pedal will prevent the engine 
from continuing to power the drive wheels at a level greater than the 
idle level, even if the accelerator linkage breaks.
    New engine control technology such as ``throttle-by-wire'' systems 
have significantly changed the nature of accelerator control functions 
and failure modes. Throttle linkages have become less common, and now 
``disconnections'' or ``severances'' as referred to in the standard 
could just as easily involve electrical wires as they could rods, 
levers, and cables. In interpretation letters, NHTSA has stated that 
electrical wires and connectors in an electronic system are analogous 
to mechanical components in a traditional system and are therefore 
covered by FMVSS No. 124. However, complexity in electronic accelerator 
control systems is much greater than in mechanical ones, especially in 
terms of the powertrain responses that can result from failures in such 
systems.
    In order to update FMVSS No. 124, NHTSA published a Request for 
Comments in 1995 (60 FR 60261) and, after consideration of comments 
received, issued an NPRM in 2002 (67 FR 48117).
    The agency proposed that the standard specify explicitly the 
components and types of disconnections and severances to be covered in 
electronic accelerator control systems. NHTSA also proposed that the 
standard include new test procedures to better address different types 
of powertrains. A manufacturer could choose any one of the test 
procedures as a basis for compliance, and a ``universal'' chassis 
dynamometer test was included as a last resort in cases where the other 
procedures were inapplicable.
    In making the proposal, NHTSA sought not to expand the scope of the 
existing Standard, but to merely clarify the standard's applicability 
to accelerator control systems associated with various powertrains 
including gasoline engines, diesel engines, electric motors, and 
hybrids. The new procedures in the proposal were all premised on return 
to a ``baseline'' idle condition measured on a normally operating 
vehicle, analogous to return of a throttle plate to the idle position.
    The proposal included three technology specific test procedures 
plus a ``universal'' test procedure. The first of the proposed 
technology specific test procedures was essentially the existing air 
throttle plate position test of the current Standard, normally 
applicable to conventional gasoline engines. The second test procedure 
was measurement of fuel flow rate, normally applicable to diesel 
engines. The third test procedure was measurement of input current to a 
drive motor, applicable to electric vehicles. The last procedure was 
measurement of drivetrain output via engine speed, conducted on a 
chassis dynamometer. This was considered a universal test because it 
could be applied to gasoline, diesel, or electric vehicles.

II. Reason for Withdrawal

    In commenting on the NPRM and in subsequent comments, the Alliance 
of

[[Page 65127]]

Automobile Manufacturers (Alliance) suggested that FMVSS No. 124 should 
include a direct measurement of powertrain output to the drive wheels. 
<SUP>1,2</SUP> The Alliance stated that this would be a ``technology-
neutral'' test and, thus, would be similar to NHTSA's proposed engine 
RPM test but with the advantage of being more easily applicable to 
hybrid powertrains in which engine RPM might not indicate drive torque. 
Subsequently, the Alliance suggested that the powertrain output test 
should measure vehicle driving speed, i.e., ``creep speed,'' rather 
than output horsepower or torque.\3\ Toyota suggested a similar 
approach, but requested that the agency consider a somewhat different 
creep speed test procedure.\4\
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    \1\ Docket NHTSA-2002-12845-10.
    \2\ Docket NHTSA-2002-12845-13.
    \3\ Docket NHTSA-2002-12845-15.
    \4\ Docket NHTSA-2002-12845-14.
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    While the agency regards these suggestions merely as variations on 
the dynamometer-based engine rpm test as proposed in the NPRM, we 
believe that additional research on the exact procedures for the 
suggested test is desirable. In particular, the agency wants to conduct 
its own tests to provide additional support for the use of a 
dynamometer for measurement of powertrain output (or possibly creep 
speed measurements), and demonstrate the feasibility of conducting 
compliance tests for all suggested approaches.
    In addition, the Alliance suggested that the agency include air 
flow rate measurement as another optional test procedure in FMVSS No. 
124. Many vehicles already have mass air flow sensors that can monitor 
air flow rate. For vehicles with sensors, the test would measure the 
air flow rate during the failsafe response for comparisons to the 
baseline idle condition. NHTSA plans to conduct research on the 
suggested air flow rate test procedure and decide on the 
appropriateness of including it in FMVSS No. 124.
    Given the time it will take to conduct research on some of the 
issues involved, NHTSA has decided not to continue an active rulemaking 
on this issue during that research. Therefore, NHTSA is withdrawing the 
rulemaking to update FMVSS No. 124.

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

    Issued: November 4, 2004.
Stephen R. Kratzke,
Associate Administrator for Rulemaking.
[FR Doc. 04-24978 Filed 11-9-04; 8:45 am]
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