GM Service Manual Online
For 1990-2009 cars only

Battery voltage is applied to the fog lamp switch from the F/TNK DR MiniFuse® #32 through CKT 2840. The foglamps will be activated when the headlamp switch is in the ON or PARK position and the foglamp switch has been momentarily depressed sending a foglamp ON request to the body control module (BCM). The BCM will then apply a ground to CKT 1317 for the front foglamps or CKT 1901 for the rear foglamps. The foglamp micro relay will then activate and send battery voltage to the foglamp indicator and the foglamps through CKT 34 (front foglamps) or CKT 122 (rear foglamps).

The frontfog lamps are grounded by CKT 150 through the Splice Pack #100 to G102. The rear foglamps are grounded by CKT 150 through Splice Packs #400 and #402 to G401.