Normal Operation
WARNING: This page is about a different car, the 2005 Mercury Montego, 2005 Ford Freestyle, and 2005 Ford Five Hundred. However, it is still accessible from the selected car via links, so may be relevant.
The smart junction box (SJB) sends a voltage reference signal to the headlamp switch through circuit 1401 (BK/LG). When the headlamp switch is placed in the PARKING LAMPS ON position, the voltage signal is routed to ground. When the SJB detects the headlamp switch in the PARKING LAMPS ON position, the SJB energizes an internal relay which routes voltage to the front parking lamps through circuit 1057 (OG/BK), and to the rear parking and license plate lamps through circuit 1058 (BN/WH).