[Federal Register Volume 70, Number 16 (Wednesday, January 26, 2005)]
[Notices]
[Pages 3765-3766]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 05-1433]
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DEPARTMENT OF TRANSPORTATION
National Highway Traffic Safety Administration
[Docket No. NHTSA 2004-17679; Notice 2]
General Motors Corporation, Denial of Petition for Decision of
Inconsequential Noncompliance
General Motors Corporation (GM), has determined that certain 2004
model year vehicles that it produced do not comply with S5.1 of 49 CFR
571.124, Federal Motor Vehicle Safety Standard (FMVSS) No. 124,
``Accelerator control systems.'' Pursuant to 49 U.S.C. 30118(d) and
30120(h), GM has petitioned for a determination that this noncompliance
is inconsequential to motor vehicle safety and has filed an appropriate
report pursuant to 49 CFR part 573, ``Defect and Noncompliance
Reports.'' Notice of receipt of a petition was published, with a 30-day
comment period, on May 19, 2004, in the Federal Register (69 FR 28977).
NHTSA received no comments.
Approximately 19,924 model year 2004 Cadillac SRX, Cadillac XLR,
and Pontiac Grand Prix vehicles are affected. S5.1 and S5.3 of FMVSS
No. 124 require that there shall be at least two sources of energy
capable of returning the throttle to the idle position from any
accelerator position or speed whenever the driver removes the opposing
actuating force. In the event of failure of one source of energy by a
single severance or disconnection, the return to idle shall occur
within three seconds for any vehicle that is exposed to ambient air at
-18 [deg]C to -40 [deg]C.
However, for the subject vehicles, in the event of failure of
either of the two Electronic Throttle Control (ETC) Pedal return
springs at ambient temperatures of -30 [deg]C to -40 [deg]C for the
Grand Prix and XLR and -10 [deg]C to -40 [deg]C for the SXR, the engine
in some of these
[[Page 3766]]
vehicles may not return to idle within the time limits specified by
S5.3.
GM believes that the noncompliance is inconsequential to motor
vehicle safety for the following reasons:
Vehicle Controllability: A number of conditions must occur for
the noncompliance to occur. A return spring must be severed, the
stack-up of tolerances in the ETC Pedal Position Sensor must exist,
the vehicle must have soaked at an ambient temperature of -30[deg] C
to -40[deg] C for the Grand Prix and XLR and -10 [deg]C to -40
[deg]C for the SXR, and the customer must drive the vehicle prior to
the vehicle interior warming up. In the extremely low likelihood of
all of these conditions existing, the condition would occur upon the
first application of the throttle pedal. The vehicle would continue
to be controllable by steering and braking, and the ETC Pedal
assembly would return to normal operation once the passenger
compartment warmed up.
Pedal Assembly is Protected: When FMVSS No. 124 was established
in 1973, the accelerator control systems of vehicles consisted of a
mechanical connection between the accelerator pedal and the engine's
carburetor. The throttle return springs required by FMVSS No. 124
were typically part of the carburetor, and subject to the harsh
engine environment. The requirements of S5.1 were established to
ensure that if one of those springs in that environment were to
fail, the engine would return to idle in a timely manner.
The ETC Accelerator Pedal Module in the subject vehicles
consists of the accelerator pedal at the end of the accelerator
pedal lever. The lever is connected to the ETC Pedal Sensor shaft,
and is returned to the idle position by two return springs. The ETC
Pedal Sensor provides two redundant signals to the engine control
module to indicate accelerator pedal position. The ETC Accelerator
Pedal Module is located entirely within the passenger compartment of
the vehicle. The return springs are in a protected area under the
instrument panel, and are not subject to the harsh environment of
the engine compartment.
Condition Requires Failed Return Spring: The condition that is
described can only occur if one of the two return springs is severed
or disconnected. The springs in the subject Accelerator Pedal
Module, however, have extremely high reliability and are not likely
to fail in the real world.
Durability Testing: The ETC Accelerator Pedal Module is designed
for a service life of at least 100,000 miles or 10 years working
life for passenger car application. The Minimum Typical Predicted
Usage Profile of the Component Technical Specification states that
the Accelerator Pedal mechanism may be subject to 35,000,000 dithers
/ 70,000,000 sensor direction changes. The GM Test Procedure TP3750,
Accelerator Pedal Lab Durability Cycling Test, that is used during
the development and validation of this system, subjects these parts
to 2 million cycles, an equivalent usage greater than 6 lives for an
automatic transmission passenger vehicle and 3 lives for a manual
transmission passenger vehicle. There were no accelerator pedal
return spring failures after testing multiple samples to 10 million
cycles during the durability testing that was performed on the ETC
Accelerator Pedal Module for the subject vehicles.
Condition Requires Extreme Temperatures, Pedal Assembly Warms
Quickly: The root cause of the condition is an increase in friction
that may occur on some ETC Accelerator Pedal Modules due to a stack-
up of tolerances, but only when the Module is subjected to extreme
ambient temperatures. All tests at temperatures above those extremes
resulted in full compliance with the FMVSS No. 124 time limits for
all pedal assemblies tested. Therefore, the ambient temperatures
required for the possibility of the noncompliance to exist are
severe. Even if a vehicle with a disconnected return spring soaked
under the necessary harsh conditions for a sufficient time, the
potential for the noncompliance to occur would exist for only a
short time, because the pedal assembly would warm up quickly with
activation of the vehicle heating system.
Warranty Data: GM has reviewed warranty data for these 2004
vehicles, as well as complaint data. GM is unaware of any data
suggesting the subject condition is a real world safety issue.
Prior NHTSA Decision: On August 3, 1998, NHTSA granted a
petition for decision of inconsequential noncompliance to GM for
1997 Chevrolet Corvettes that failed to meet the requirements of
FMVSS No. 124, with respect to the requirement to return to idle in
less than 3 seconds at -40 [deg]C.
Additional information was requested from GM. One of the factors
considered in the prior petition grant (63 FR 41320, August 3, 1998)
was that the accelerator control system performance of the Corvettes
improved after several thousand application cycles of the accelerator
pedal.
However, in the present case, GM and its pedal assembly supplier
conducted several tests of samples from the subject population
attempting to demonstrate this kind of improvement by cycling pedal
assemblies at ambient and cold temperatures, but the throttle return
performance was not significantly improved.
Six accelerator pedal assemblies were taken from GM vehicles with
up to 11,553 accumulated driving miles and tested on a fixture with one
return spring disconnected at -40 [deg]C and higher temperatures.
Checking times to return from 10 percent, 50 percent, and 100 percent
wide-open throttle positions to idle, two of the assemblies returned to
idle within three seconds. The four others had not fully returned
within one minute.
The worst performer of these assemblies was installed in a vehicle
for testing on a dynamometer in a cold chamber. The driver accelerated
to 70 mph and removed his foot from the accelerator control pedal.
Vehicle speed reduced slowly. Tapping or pumping the accelerator pedal
had little affect. Side taps applied to the pedal improved return time
such that the pedal returned within 40-50 seconds. When the driver used
his foot to lift up the pedal, the idle condition was achieved within
five seconds.
The standard requires that a vehicle's accelerator control system,
with one return spring disconnected, return to idle in cold ambient
temperatures within three seconds. A driver who starts a vehicle
affected by the noncompliance in these conditions and begins driving it
soon thereafter could be unable to control vehicle speed and experience
a loss of control.
In consideration of the foregoing, NHTSA has decided that the
petitioner has not met its burden of persuasion that the noncompliance
described is inconsequential to motor vehicle safety. Accordingly, GM's
petition is denied.
Authority: 49 U.S.C. 30118, 30120; delegations of authority at
CFR 1.50 and 501.8.
Issued on: January 19, 2005.
Claude H. Harris,
Director, Office of Vehicle Safety Compliance.
[FR Doc. 05-1433 Filed 1-25-05; 8:45 am]
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