Front Fog Lamps
WARNING: This page is about a different car, the 2011 Cadillac DTS. However, it is still accessible from the selected car via links, so may be relevant.
When the fog lamp switch is turned ON, ground is applied through the fog lamp switch signal circuit to the body control module (BCM) indicating the fog lamps ON request. In response to this signal, the BCM applies ground to the fog lamp relay control circuit energizing the FOG LAMP PCB Relay. With the relay energized, battery voltage is applied through the switch side of the relay, the FOG fuse, and the fog lamp supply voltage circuits illuminating the fog lamps. At the same time the BCM sends a serial data message to the instrument panel cluster (IPC) requesting that the fog lamp indicator be illuminated.