GM Service Manual Online
For 1990-2009 cars only

Voltage is supplied to the fog lamp relay coil through CKT 74 (LT BLU) when the park lamps are turned on. Voltage is supplied to the load feed side of the relay at all times from the FOG LP fuse. The fog lamp relay coil is grounded through the body control module (BCM) when the fog lamp switch is turned ON. Voltage is provided to the front fog lamps or rear fog lamps (Export) through CKT 34 (PPL) with the fog lamp relay energized.

A voltage signal is also sent from the fog lamp relay to the fog lamp indicator on the fog lamp switch. The voltage signal informs the driver that the fog lamps are on.

Ground for the front fog lamps is provided by CKT 150 (BLK) for the left front fog lamp to G111 and to CKT 250 (BLK) for the right front fog lamp to G112.

Ground for the rear fog lamps is provided by CKT 1350 (BLK) to G450.

Foglamp relay control is interrupted by the body control module (BCM) when the headlamp high beams are ON.