GM Service Manual Online
For 1990-2009 cars only

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

  1. Place the front fog lamp switch in the ON position.
  2. Remove the front fog lamp relay.
  3. 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

  1. Remove the fog lamp switch.
  2. Place a fused jumper between the fog lamp switch signal and ground connector terminals.
  3. 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

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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 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

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19

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 3