Rear Fog Lamps

WARNING: This page is about a different car, the 2008 Cadillac CTS. However, it is still accessible from the selected car via links, so may be relevant.

The rear fog lamp relay coil and switch terminals are supplied with battery voltage at all times. Ground is applied at all times at G200 to the rear fog lamp switch inside of the turn signal/multifunction switch. When the rear fog lamp switch is placed in the ON position, ground is applied through the rear fog lamp switch signal circuit to the body control module (BCM). Battery voltage is applied at all times from the REAR FOG LAMP fuse to the REAR FOG LAMP relay. The BCM applies ground through the rear fog lamp relay control circuit to the coil side of the REAR FOG LAMP relay causing the relay coil to energize. When the relay is energized, the switch contacts close and battery voltage is applied from the REAR FOG LAMP fuse through the relay, to the rear fog lamps. Ground for the rear fog lamps is applied at all times at G402.

The BCM will send a message via GMLAN serial data to the instrument panel cluster (IPC) to enable the rear fog lamp indicator.