Interpretation ID: nht92-5.2

DATE: August 3, 1992

FROM: Gary L. Hopkins -- VP & G.M. Control Systems Products, Bendix Heavy Vehicle Systems

TO: Office of Chief Counsel -- NHTSA

TITLE: Request for Interpretation - Motor Vehicle Safety Standard No. 124; Accelerator Control Systems (FMVSS #124)

ATTACHMT: Attached to letter dated 9/23/92 from Paul Jackson Rice to Gary L. Hopkins (A39; Std. 124)

TEXT:

Bendix Heavy Vehicle Systems of Allied-Signal Inc. (BHVS) manufactures electronic treadle assemblies that are utilized by several vehicle manufacturers as a component of their acceleration control system used with electronically controlled diesel engines. The BHVS electronic treadle assembly (see attachment) modulates an electric signal, received from an outside source, in response to the input of the operator's foot. This signal is an input to the engine electronic controller which in turn provides electronic signals that operate the engine fuel injectors to control engine power. (See attached schematic of a typical electronic engine control system).

The scope and requirements of FMVSS #124, which is a standard last updated in 1973, are specific as to the return of the vehicles throttle to the idle position. The BHVS electronic treadle assembly is not a throttle as it is not a component of the fuel metering device, nor is BHVS aware of any component on an electronic controlled diesel engine that is a throttle as defined by the standard. Therefore, it is our interpretation and opinion that FMVSS #124 is not applicable to the BHVS electronic treadle assemblies and electronic controlled diesel engines.

While BHVS has taken the above stated position on the applicability of FMVSS #124, it is recognized that until an appropriate standard is issued good safety design practices shall continue to be applied. Therefore, a malfunction in the accelerator control system that results in loss of vehicle control would be a safety related issue, not a compliance issue.

To be specific, BHVS is hereby requesting confirmation of our position that vehicles equipped with electronic engine control systems of the type as described and depicted in the schematic and which include an electronic treadle assembly are not covered by the scope and requirements of FMVSS #124.

If additional information is necessary, please contact me at (216) 329-9200.

(Drawings omitted)