Shift Interlock System
WARNING: This page is about a different car, the 2004 Lincoln Navigator and 2004 Ford Expedition. However, it is still accessible from the selected car via links, so may be relevant.
The shift interlock system prevents the shifting from PARK unless the brake pedal is depressed. The shift interlock system consists of a shift lock actuator mounted at the base of the steering column or on the floor shifter mechanism. If the ignition switch is in the RUN position, the shift lock actuator is on unless the brake pedal is depressed.