Fog Lamps Always On

FOG LAMPS ALWAYS ON




DIAGNOSTIC FAULT INFORMATION

IMPORTANT: Always perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Testing and Inspection

CIRCUIT/SYSTEM DESCRIPTION
When the fog lamp switch is placed in the ON position, ground is applied through the fog lamp switch signal circuit at G201 to the body control module (BCM). The BCM applies battery voltage through the fog lamp relay control circuit to the coil side of the fog lamp relay and the fog lamps ON indicator located on the fog lamp switch. Battery voltage is applied at all times from the FOG LP fuse to the switch side of the fog lamp relay. When the relay coil is energized, the relay switch contacts close and allow battery voltage to be applied from the FOG LP fuse, through the relay switch contacts, to the fog lamps. Ground for the fog lamps is applied at all times at G101 for the left fog lamp and G102 for the right fog lamp. G101 also serves as ground for the coil side of the fog lamp relay.

CIRCUIT/SYSTEM TESTING
1. Ignition OFF, disconnect the fog lamp relay.
2. Ignition ON, verify that the fog lamps are off.
- If the fog lamps are still on, repair the front fog lamp voltage supply circuit for a short to voltage.
3. Connect a test lamp between the fog lamp relay control circuit and ground at the fog lamp relay terminals. The test lamp should not illuminate.
- If the test lamp does not illuminate, replace the fog lamp relay.
4. Ignition OFF, disconnect the BCM C2 harness connector.
5. Ignition ON, verify that the test lamp does not illuminate.
- If the test lamp illuminates, repair the fog lamp relay control circuit for a short to voltage. If the circuit tests normal, replace the BCM.
6. Ignition OFF, disconnect the fog lamp switch.
7. Verify that a test lamp does not illuminate between battery voltage and the fog lamp switch signal circuit at the fog lamp switch harness connector.
- If the test lamp illuminates, repair the fog lamp switch signal circuit for a short to ground.
8. If all circuits test normal, replace the fog lamp switch.

REPAIR INSTRUCTIONS

IMPORTANT: Always perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests

- Control Module References for BCM replacement, setup, and programming
- Fog Lamp Switch Replacement - Front
- Underhood Electrical Center or Junction Block Replacement
- Relay Replacement (Within an Electrical Center) Relay Replacement (Attached to Wire Harness)