Park Lock System
WARNING: This page is about a different car, the 2002 Oldsmobile Bravada, 2002 GMC Envoy XL, 2002 GMC Envoy, and 2002 Chevrolet TrailBlazer. However, it is still accessible from the selected car via links, so may be relevant.
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 switch in the ON position, voltage is supplied to the park lock solenoid. The park lock solenoid energizes through a permanent ground unlocking the gearshift lever. With the ignition switch in the OFF or ACC position, the park lock solenoid de-energizes and locks the gearshift lever in the Park position.