The automatic transmission shift lock control is a safety device that prevents an inadvertent shift out of PARK when the ignition is ON. 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 park/neutral position switch. When the transmission is in the PARK position the contacts in the park/neutral position switch are closed. This allows current to flow through the switch to the automatic transmission shift lock control switch. The circuit continues through the normally-closed switch to the automatic transmission shift lock control solenoid. The automatic transmission shift lock control solenoid is permanently grounded. This energizes the automatic transmission shift lock control solenoid, locking the shift linkage in the PARK position. When the driver presses the brake pedal the contacts in the automatic transmission shift lock control switch open, causing the automatic transmission shift lock control solenoid to release. This allows the shift lever to move from the PARK position.

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. The system consists of the park lock solenoid. With the ignition in the ON position, voltage is supplied to the park lock solenoid. The park lock solenoid energizes through a permanent ground unlocking the shift lever. With the ignition in the OFF or ACCY position the park lock solenoid de-energizes and locks the shift lever in the park position.