Circuit/System Description
WARNING: This page is about a different car, the 2006 Buick Lucerne. However, it is still accessible from the selected car via links, so may be relevant.
The fog lamps are controlled by the body control module (BCM) by inputs from the for lamp switch. When the BCM receives a fog lamps ON command, it grounds the fog lamp relay control circuit in order to energize 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 lamps supply voltage circuits to the fog lamps.