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, the tramsmission control module supplies ignition voltage to the automatic transmission park interlock relay. The relay coil is permanently grounded. When the relay is energized, the brake applied voltage signal continues to the automatic transmission shift lock control solenoid. The automatic transmission shift lock control solenoid is also permanently grounded. This energizes the automatic transmission shift lock control solenoid allowing the transmission shift lever to be moved from the PARK position. When the brake pedal is released, the contacts in the stop lamp switch open, de-energizing the automatic transmission shift lock control solenoid. This locks the shift lever in the PARK position.