[Code of Federal Regulations]
[Title 49, Volume 5]
[Revised as of October 1, 2002]
From the U.S. Government Printing Office via GPO Access
[CITE: 49CFR571.124]

[Page 407]
 
                        TITLE 49--TRANSPORTATION
 
                            OF TRANSPORTATION
 
PART 571--FEDERAL MOTOR VEHICLE SAFETY STANDARDS--Table of Contents
 
            Subpart B--Federal Motor Vehicle Safety Standards
 
Sec. 571.124  Standard No. 124; Accelerator control systems.

    S1. Scope. This standard establishes requirements for the return of 
a vehicle's throttle to the idle position when the driver removes the 
actuating force from the accelerator control, or in the event of a 
severance or disconnection in the accelerator control system.
    S2. Purpose. The purpose of this standard is to reduce deaths and 
injuries resulting from engine overspeed caused by malfunctions in the 
accelerator control system.
    S3. Application. This standard applies to passenger cars, multi-
purpose passenger vehicles, trucks, and buses.
    S4. Definitions.
    S4.1  Driver-operated accelerator control system means all vehicle 
components, except the fuel metering device, that regulate engine speed 
in direct response to movement of the driver-operated control and that 
return the throttle to the idle position upon release of the actuating 
force.
    Fuel metering device means the carburetor, or in the case of certain 
engines the fuel injector, fuel distributor or fuel injection pump.
    Throttle means the component of the fuel metering device that 
connects to the driver-operated accelerator control system and that by 
input from the driver-operated accelerator control system controls the 
engine speed.
    Idle position means the position of the throttle at which it first 
comes in contact with an engine idle speed control appropriate for 
existing conditions according to the manufacturers' recommendations. 
These conditions include, but are not limited to, engine speed 
adjustments for cold engine, air conditioning, and emission control, and 
the use of throttle setting devices.
    Ambient temperature means the surrounding air temperature, at a 
distance such that it is not significantly affected by heat from the 
vehicle under test.
    S4.2  In the case of vehicles powered by electric motors, the words 
throttle and idle refer to the motor speed controller and motor 
shutdown, respectively.
    S5. Requirements. The vehicle shall meet the following requirements 
when the engine is running under any load condition, and at any ambient 
temperature between -40 degrees Celsius and +52 degrees Celsius after 12 
hours of conditioning at any temperature within that range.
    S5.1  There shall be at least two sources of energy capable of 
returning the throttle to the idle position within the time limit 
specified by S5.3 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 
throttle shall return to the idle position within the time limits 
specified by S5.3, from any accelerator position or speed whenever the 
driver removes the opposing actuating force.
    S5.2  The throttle shall return to the idle position from any 
accelerator position or any speed of which the engine is capable 
whenever any one component of the accelerator control system is 
disconnected or severed at a single point. The return to idle shall 
occur within the time limit specified by S5.3, measured either from the 
time of severance or disconnection or from the first removal of the 
opposing actuating force by the driver.
    S5.3  Except as provided below, maximum time to return to idle 
position shall be 1 second for vehicles of 4536 kilograms or less GVWR, 
and 2 seconds for vehicles of more than 4536 kilograms GVWR. Maximum 
time to return to idle position shall be 3 seconds for any vehicle that 
is exposed to ambient air at -18 degrees Celsius to -40 degrees Celsius 
during the test or for any portion of the 12-hour conditioning period.

[38 FR 2980, Jan. 31, 1973; as amended at 60 FR 13645, Mar. 14, 1995]