Normal Operation
WARNING: This page is about a different car, the 2006 Mercury Milan, 2006 Lincoln Zephyr, and 2006 Ford Fusion. However, it is still accessible from the selected car via links, so may be relevant.
The smart junction box (SJB) sends a reference signal to the headlamp switch through circuit CLF21 (GY/VT). When the fog lamp switch is engaged, the voltage signal is routed to ground.
When the SJB detects the fog lamps on request, the SJB provides voltage to the fog lamp relay coil through circuit CLF29 (BN). When the fog lamp relay is energized, voltage is routed through circuit CLF12 (BN/YE) to the fog lamps.