Fog Lamps

WARNING: This page is about a different car, the 2021 Ford F-150. However, it is still accessible from the selected car via links, so may be relevant.

System Diagram

Courtesy of FORD MOTOR CO.

Fog Lamps

The headlamp switch sends a status message over the LIN circuit to the BCM to indicate the headlamp switch status (position or a fault with the headlamp switch). The BCM turns the parking lamps and headlamps on when the ignition is in RUN and the BCM detects a fault from the headlamp switch or wiring. This is normal behavior of the BCM when a fault has been detected with the inputs from the headlamp switch.

When the BCM receives input from the headlamp switch indicating a request for the fog lamps, the BCM provides voltage to the fog lamps.

If equipped, when the vehicle is in snow plow mode, the front fog lamps are disabled.

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 fog lamp output circuit driver.