Rear Fog Lamps Always On

WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2007 GMC Yukon XL, 2007 GMC Yukon, 2007 Chevrolet Tahoe, 2007 Chevrolet Suburban, and 2007 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.

Step	Action	Yes	No
Schematic Reference: Fog Lights Schematics Connector End View Reference: Lighting Systems Connector End Views or Data Communication Connector End Views
1	Did you perform the Diagnostic System Check - Vehicle?	Go to Step 2	Go to Diagnostic System Check - Vehicle
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	Go to Step 3
3	Use the scan tool to monitor the rear fog lamp switch input in the auxiliary body control module (XBCM) data list while depressing the switch several times. Does the scan tool indicate that the switch is ACTIVE at all times?	Go to Step 4	Go to Step 5
4	Test for a short to ground in the rear fog lamp switch signal circuit. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition?	Go to Step 9	Go to Step 8
5	Test for a short to voltage in the rear fog lamp supply voltage circuit. Refer to Circuit Testing and Wiring Repairs . Did you complete the repair?	Go to Step 9	Go to Step 6
6	Inspect for poor connections at the harness connector of the XBCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition?	Go to Step 9	Go to Step 7
7	Replace the XBCM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement?	Go to Step 9	-
8	Replace the headlamp switch. Refer to Headlamp Switch Replacement . Did you complete the repair?	Go to Step 9	-
9	Operate the system in order to verify the repair. Did you correct the condition?	System OK	Go to Step 3