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, voltage is supplied to automatic transmission shift lock control switch. Voltage flows through the normally closed contacts of the automatic transmission shift lock control switch to the automatic transmission shift lock control solenoid. When the body control module (BCM) receives a class 2 message from the powertrain control module indicating the transmission is in the park position the BCM grounds the automatic transmission shift lock solenoid control circuit . This energizes the automatic transmission shift lock control solenoid causing the transmission shift lever to be physically locked in the PARK position. When the brake pedal is pressed 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 be move out of the PARK position.

Vehicles equipped with a floor shift have a park lock solenoid. The park lock solenoid is a safety device that prevents an inadvertent shift out of PARK when the key is in the OFF position. The key must be in the RUN position to release the park lock solenoid.

1. The system consists of the park lock solenoid.
2. The body control module (BCM)

With the ignition in the ON position, voltage is supplied to the park lock solenoid. The park lock solenoid energizes through a controlled ground at the body control module. When the body control module (BCM) receives a class 2 message from the powertrain control module indicating the transmission is in the park position the BCM grounds the control circuit. With the ignition in the OFF or ACCY position the park lock solenoid de-energizes and mechanically locks the shift lever in the park position.