Brake Shift Interlock System
WARNING: This page is about a different car, the 2011 Mercury Milan, 2011 Lincoln MKZ, and 2011 Ford Fusion. However, it is still accessible from the selected car via links, so may be relevant.
The brake shift interlock system prevents a shift out of PARK unless the brake pedal is depressed. The brake shift interlock system has a Brake Shift Interlock Actuator (BSIA) mounted on the floor selector lever assembly. If the ignition switch is in the RUN position, the BSIA is continually on unless the brake pedal is depressed.