Diagnostic Aids

WARNING: This page is about a different car, the 2004 GMC Sierra, 2004 GMC Cab & Chassis Sierra, 2004 Chevrolet Silverado, and 2004 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

Test the rear fog lamp switch for sticking in the ON position.
Perform a visual inspection for loose or poor connections at all related components. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

DTC B2537

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	Install a scan tool. Turn ON the ignition, with the engine OFF. With a scan tool, observe the rear fog lamp switch parameter in the Body Control Module (BCM) data list. Does the scan tool display INACTIVE?	Go to Step 3	Go to Step 4
3	Activate the front fog lamp switch. Activate the rear fog lamp switch. With the scan tool, observe the rear fog lamp switch data parameter. Does the rear fog lamp switch data parameter change state?	Go to Diagnostic Aids	Go to Step 4
4	Turn OFF the ignition. Disconnect the rear fog lamp switch. Turn ON the ignition, with the engine OFF. With a scan tool, observe the rear fog lamp switch data parameter. Does the scan tool display INACTIVE?	Go to Step 7	Go to Step 5
5	Test the signal circuit of the rear fog lamp switch for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?	Go to Step 10	Go to Step 6
6	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 10	Go to Step 8
7	Inspect for poor connections at the harness connector of the rear fog lamp switch. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?	Go to Step 10	Go to Step 9
8	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 10	-
9	Replace the rear fog lamp switch. Refer to Fog Lamp Switch Replacement - Rear . Did you complete the replacement?	Go to Step 10	-
10	Use the scan tool in order to clear the DTCs. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text. Does the DTC reset?	Go to Step 2	System OK