Shift Interlock: Description and Operation

DESCRIPTION
A shift interlock mechanism is installed on vehicles with an automatic transmission to prevent shifting the transmission out of the PARK position unless the brake pedal is depressed.

CONSTRUCTION
The transmission shift control linkage consists of a floor mounted shifter assembly, a cable connecting the shifter to the transmission shift lever, an interlock cable connecting the shifter to the steering column lock assembly, a solenoid assembly attached to the key interlock assembly, a bracket retaining the solenoid, and the necessary wiring.

OPERATION
The interlock cable locks the shift lever in the PARK position when the ignition switch is in the LOCK position. It also requires the shift lever to be in the PARK position to turn the ignition switch to the LOCK position. The solenoid is energized when the ignition switch is turned to the ON position, locking the shifter in the PARK position. When the brake pedal is depressed and the stoplamp switch is activated, the shift lock solenoid is deactivated and the shifter can be moved out of the PARK position.