Power Door Locks
WARNING: This page is about a different car, the 2004 Ford Ranger. However, it is still accessible from the selected car via links, so may be relevant.
The smart junction box (SJB) controls the power door lock and keyless entry system. The lock and unlock operation is carried out by supplying ground to the SJB from either door lock control switch. The door lock actuators ground through the SJB. The door lock control switch will lock and unlock all doors by grounding the appropriate circuit to the SJB. The SJB then supplies power to the appropriate door lock actuator circuits to lock or unlock the doors.