The automatic transmission shift lock control system is a safety device that prevents an inadvertent shift 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. The system consists of the following components:

With the ignition in the ON position, battery positive voltage is supplied to the stop lamp switch and to the switch side of the automatic transmission shift lock control relay. The circuit continues through the normally-closed stop lamp switch to the coil of the automatic transmission shift lock control relay. The coil of the shift lock control relay is permanently grounded. With the automatic transmission shift lock control solenoid energized the shift lever is mechanically locked in the PARK position. When the driver presses the brake pedal, the contacts in the automatic transmission shift lock control switch open, de-energizing the automatic transmission shift lock control solenoid. This allows the shift lever to move from the PARK position.