Fog Lamps
WARNING: This page is about a different car, the 2018 Lincoln Navigator. However, it is still accessible from the selected car via links, so may be relevant.
The BCM monitors the headlamp switch position by sending voltage signals on multiple circuits to the headlamp switch. There is one circuit for each headlamp switch position. At any given time, one of the signal circuits is switched to ground to indicate the headlamp switch position.
When the BCM receives input from the headlamp switch indicating a request for the fog lamps, the BCM provides voltage to the fog lamps.
The BCM also provides Field Effect Transistor (FET) protection of the rear fog lamp output circuit. When an excessive current draw is detected, the BCM disables the front or rear fog lamp output circuit driver. Refer to: Module Controlled Functions - System Operation and Component Description .