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 always on.

Do the front fog lamps operate normally?

Go to Testing for Intermittent Conditions and Poor Connections

Go to Step 3

3

Remove the front fog lamp relay.

Do the front fog lamps turn OFF?

Go to Step 4

Go to Step 7

4

  1. Ensure that the front fog lamp switch is in the OFF position.
  2. 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 found?

Go to Step 5

Go to Step 9

5

Test the front fog lamp relay control circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs .

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 .

Did you find and correct the condition?

Go to Step 10

Go to Step 8

7

Repair the short to voltage in the front fog lamp supply voltage circuit. Refer to Wiring Repairs .

Did you complete the repair?

Go to Step 10

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8

Replace the BCM. Refer to Control Module References .

Did you complete the replacement?

Go to Step 10

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9

Replace the front fog lamp relay. Refer to Relay Replacement .

Did you complete the repair?

Go to Step 10

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10

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 3