Normal Operation
WARNING: This page is about a different car, the 2005 Mercury Mountaineer and 2005 Ford Explorer. However, it is still accessible from the selected car via links, so may be relevant.
With the headlamp switch turned to the autolamp position, a battery voltage signal is sent to the vehicle security module through circuit 1399 (DB/WH). The vehicle security module then determines the amount of ambient light based on the input received from the light sensor. The input signal is received through circuit 218 (WH/VT). When the ambient level has reached a point (determined by the internal programming of the vehicle security module), two internal relays are energized to supply power to the exterior lamps. Circuit 1205 (BK) is the ground circuit for the light sensor.