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 signal, 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 LAMPS Fuse, and the fog lamps supply voltage circuits to the fog lamps.

The ignition is ON. Park lamps must be ON and the fog lamps must be commanded ON.

The BCM detects a short to voltage on the front fog lamp control circuit while trying to apply a ground to the circuit.

The BCM will deactivate the fog lamp relay for the remainder of the ignition cycle.

Schematic Reference

Fog Lights Schematics

Connector End View Reference

Lighting Systems Connector End Views

Electrical Information Reference

Scan Tool Reference

Ignition ON, turn the park lamps ON. Press the front fog lamp switch. The front fog lamps should illuminate.

1. Ignition OFF, disconnect the (C2) harness connector at the underhood fuse block.
2. Connect a test lamp between the control circuit terminal H5 and B+.
3. Ignition ON, command the Fog Lamps ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.

⇒	If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the BCM.

⇒	If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.

4. If all circuits test normal, replace the underhood fuse block.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.