Fog Lamps Always On - Rear
WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2004 Oldsmobile Bravada, 2004 GMC Envoy XUV, 2004 GMC Envoy XL, 2004 GMC Envoy, and 2004 Chevrolet TrailBlazer. However, it is still accessible from the selected car via links, so may be relevant.
Fog Lamps Always On - Rear Diagnostic Test
| Step | Action | Yes | No |
|---|---|---|---|
| Schematic Reference: Fog Lights Schematics Connector End View Reference: Lighting Systems Connector End Views or Body Control System Connector End Views in Body Control System |
|||
| 1 | Did you perform the Lighting Systems Diagnostic System Check? | Go to Step 2 | Go to Diagnostic System Check - Lighting Systems |
| 2 | Verify that the rear fog lamp is always on. Does the rear fog lamp operate normally? |
Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3 |
| 3 | Use the scan tool to monitor the rear fog lamp switch input with the switch in the OFF position. Does the scan tool indicate that the switch is ON? |
Go to Step 4 | Go to Step 5 |
| 4 | Test for a short to ground in the rear fog lamp switch signal circuit. Did you find and correct the condition? |
Go to Step 12 | Go to Step 10 |
| 5 | Remove the rear fog lamp relay. Does the rear fog lamp turn OFF? |
Go to Step 6 | Go to Step 8 |
| 6 |
|
Go to Step 7 | Go to Step 11 |
| 7 | Inspect for poor connections at the harness connector of the Body Control Module (BCM). Refer to Circuit Testing
and Wiring Repairs
in Wiring Systems. Did you find and correct the condition? |
Go to Step 12 | Go to Step 9 |
| 8 | Repair the short to voltage in the rear fog lamp supply voltage circuit. Refer to Wiring Repairs
in Wiring Systems. Did you complete the repair? |
Go to Step 12 | - |
| 9 |
IMPORTANT:
Perform the setup procedure for the BCM. Replace the body control module (BCM). Refer to Body Control Module Replacement
in Body Control System.Did you complete the replacement? |
Go to Step 12 | - |
| 10 | Replace the rear fog lamp switch. Refer to Headlamp Switch Replacement . Did you complete the repair? |
Go to Step 12 | - |
| 11 | Replace the rear fog lamp relay. Refer to Relay Replacement (Within an Electrical Center)
or Relay Replacement (Attached to Wire Harness)
in Wiring Systems. Did you complete the repair? |
Go to Step 12 | - |
| 12 | Operate the system in order to verify the repair. Did you correct the condition? |
System OK | Go to Step 3 |