Shift Interlock: Description and Operation

Automatic Transmission Shift Lock Control Description and Operation
The automatic transmission shift lock control system is a safety device that prevents an inadvertent shift of the transmission out of PARK when the engine is running. The driver must press the brake pedal before moving the shift lever out of the park position.

Shift lock Control With Cruise Control
The system consists of the following components:
^ The shift lock relay
^ The shift lock solenoid

When the vehicle is in PARK, the transmission range switch is closed and ignition voltage is supplied to the switch of the shift lock relay. When the brake pedal is applied, the stoplamp switch closes and battery voltage is supplied to the coil of the shift lock relay. The coil is grounded at G105 and the relay energizes. The energized shift lock relay applies voltage to the shift lock solenoid which energizes and releases the locking tab on the floor shifter.

Shift lock Control Without Cruise Control
The system consists of the following components:
^ The stoplamp switch
^ The shift lock solenoid

When the vehicle is in PARK, the transmission range switch is closed and ignition voltage is supplied to the stoplamp switch. When the brake pedal is applied, the stoplamp switch closes and battery voltage is applied to the shift lock solenoid which energizes and releases the locking tab on the floor shifter.