Interpretation ID: 3167yy
Design Engineer
Imo Industries, Inc.
Morse Controls Division
21 Clinton Street
Hudson, OH 44236-2899
Dear Mr. Reed:
This responds to your letter concerning Federal Motor Vehicle Safety Standard No. 102, Transmission shift lever sequence, starter interlock, and transmission braking effect, as it relates to electronic transmission shift controls that operate automatic transmissions used in heavy duty trucks and RV's and on solenoid operated powershift transmissions used in various on and off highway vehicles. You asked whether "the intent of [section S3.l.3 of the standard] is to render the engine starter inoperative when the transmission is in a forward or reverse drive gear or when the shift lever . . . is in such a gear." As discussed below, Standard No. 102 expressly provides that the engine starter shall be inoperative when the transmission shift lever is in a forward or reverse drive position.
By way of background information, the National Highway Traffic Safety Administration (NHTSA) does not provide approvals of motor vehicles or motor vehicle equipment. Under the National Traffic and Motor Vehicle Safety Act, it is the responsibility of the manufacturer to ensure that its vehicles and equipment meet applicable standards. The following provides our opinion based on the facts provided in your letter.
Section S3.l.3 of Standard No. 102 reads as follows:
S3.1.3 Starter interlock. The engine starter shall be inoperative when the transmission shift lever is in a forward or reverse drive position.
The standard thus expressly provides that the engine starter shall be inoperative when the transmission shift lever is in a forward or reverse drive position.
You state in your letter that "(t)he interests of public safety will be best served by requiring that the engine starter be inoperative when the transmission itself, not the transmission shift lever, is in a forward or reverse drive gear." According to your letter, with the introduction of electronic shift systems and fully electronic transmissions, the connection between the shift lever and the transmission is rarely performed by direct mechanical means, and there is a possibility that the shift lever position may not match the gear currently engaged by the transmission in situations where the transmission control circuitry overrides the shift lever selection in the interest of safety, transmission protection or other criteria related to specific applications. You state that any attempt to artificially match the electronic shift lever's position to the gear currently enaged by the transmission in such override situations involves added cost and complexity, as well as safety and reliability concerns. You also argue that requiring the shift lever to be moved to neutral when the transmission itself is already in neutral due to some override condition imposes unnecessary safety hazards in some applications.