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 reference signal to the light sensor through circuit 1416 (YE/WH). When the headlamp switch is placed in the AUTOLAMPS ON position, the SJB monitors the ambient light conditions based on the input received from the light sensor. When the ambient light level has reached a point (determined by the internal programming of the SJB), the SJB provides voltage to the headlamps, parking and license plate lamps.