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 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 front fog lamps are inoperative.

Do the front fog lamps operate normally?

Go to Testing for Intermittent Conditions and Poor Connections

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.
  2. If no problem is 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 .

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 .

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.
  3. Test for a ground signal at the front fog lamp relay control circuit terminal in the underhood fuse block. Refer to Circuit Testing .

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 .

Did you find and correct a condition?

Go to Step 16

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 .

Was a ground 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. Refer to Circuit Testing and Wiring Repairs .

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 .

Did you find and correct the condition?

Go to Step 16

Go to Step 13

13

Replace the BCM. Refer to Control Module References 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 .

Did you complete the repair?

Go to Step 16

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15

Replace the front fog lamp switch. Refer to Headlamp Switch Replacement .

Did you complete the repair?

Go to Step 16

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16

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 3