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 Computer/Integrating Systems Connector End Views in Computer/Integrating Systems

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

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 5

4

  1. Inspect the inoperative bulb and socket for an open filament or poor terminal contact and replace as necessary. Refer to Front Fog Lamp Bulb Replacement .
  2. If a condition is not found, locate and repair the open or high resistance in the front fog lamp supply voltage circuit or ground circuit to the inoperative lamp. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 16

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5

With the engine OFF, turn the key to RUN and the headlamp switch to PARK.

Do the park lamps illuminate?

Go to Step 6

Go to Symptoms - Lighting Systems

6

Inspect the FOG LP fuse.

Is the fuse open?

Go to Step 7

Go to Step 8

7

Test for a short to ground 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 16

Go to Step 14

8

  1. Place the front fog lamp switch in the ON position.
  2. Remove the front fog lamp relay. Refer to Relay Replacement in Wiring Systems.
  3. Test for a voltage signal at the fog lamp relay control circuit terminal for the front fog lamp relay in the underhood fuse block. Refer to Electrical Center Identification Views and Circuit Testing in Wiring Systems.

Was a voltage signal present?

Go to Step 11

Go to Step 9

9

Test the front fog lamp switch signal and ground circuits for an open, high resistance, or short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct a condition?

Go to Step 16

Go to Step 10

10

  1. Remove the fog lamp switch. Refer to Headlamp Switch Replacement .
  2. Place a fused jumper between the fog lamp switch signal and ground connector terminals.
  3. Test for a voltage signal at the fog lamp relay control circuit terminal for the front fog lamp relay in the underhood fuse block. Refer to Electrical Center Identification Views and Circuit Testing in Wiring Systems.

Was a voltage signal present?

Go to Step 15

Go to Step 12

11

Test for an open or high resistance in the front fog lamp supply voltage circuit and fog lamp ground circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct a condition?

Go to Step 16

Go to Step 14

12

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 16

Go to Step 13

13

Replace the BCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.

Did you complete the replacement?

Go to Step 16

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14

Replace the front fog lamp relay. Refer to Relay Replacement in Wiring Systems.

Did you complete the repair?

Go to Step 16

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15

Replace the headlamp and panel dimmer switch. Refer to Headlamp Switch Replacement .

Did you complete the repair?

Go to Step 16

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16

  1. Use the scan tool in order to clear any induced DTCs.
  2. Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 3