Fog Lamps Inoperative

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.

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 front fog lamps are inoperative. Do the front fog lamps operate normally?	Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems	Go to Step 3
3	Is only one front fog lamp inoperative?	Go to Step 4	Go to Step 6
4	Inspect the inoperative bulb and socket for an open filament or poor terminal contact and repair or replace as necessary. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?	Go to Step 19	Go to Step 5
5	Test the ground circuit of the inoperative lamp for a high resistance or an open. Did you find and correct the condition?	Go to Step 19	Go to Step 15
6	With the engine Off, turn the key to RUN and the headlamp switch to PARK. Do the park lamps illuminate?	Go to Step 7	Go to Park, License, and Tail Lamps Inoperative
7	Inspect the FOG LP fuse. Is the fuse open?	Go to Step 14	Go to Step 8
8	Place the front fog lamp switch in the ON position. Remove the front fog lamp relay. Test for a ground signal at the front fog lamp relay control circuit terminal in the underhood fuse block. Refer to Circuit Testing in Wiring Systems. Was a ground signal present?	Go to Step 11	Go to Step 9
9	Test the front fog lamp switch signal and ground circuits for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct a condition?	Go to Step 19	Go to Step 10
10	Remove the fog lamp switch. Place a fused jumper between the fog lamp switch signal and ground connector terminals. Test for a ground signal at the front fog lamp relay control circuit terminal in the underhood fuse block. Refer to Circuit Testing in Wiring Systems. Was a ground signal present?	Go to Step 18	Go to Step 12
11	Test for an open or high resistance in the front fog lamp supply voltage circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct a condition?	Go to Step 19	Go to Step 17
12	Test the fog lamp relay control circuit for an open high resistance or a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?	Go to Step 19	Go to Step 13
13	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 19	Go to Step 16
14	Repair the fog lamp supply circuit of the inoperative lamp for a short to ground. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair?	Go to Step 19	-
15	Repair the fog lamp supply circuit of the inoperative lamp. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair?	Go to Step 19	-
16	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 19	-
17	Replace the front 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 19	-
18	Replace the front fog lamp switch. Refer to Headlamp Switch Replacement . Did you complete the repair?	Go to Step 19	-
19	Operate the system in order to verify the repair. Did you correct the condition?	System OK	Go to Step 3