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 rear fog lamp is inoperative.

Does the rear fog lamp operate normally?

Go to Testing for Intermittent Conditions and Poor Connections

Go to Step 3

3

Inspect for an open rear fog lamp bulb filament or poor connections/corroded terminals at the lamp socket. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find a condition?

Go to Step 8

Go to Step 4

4

Use the scan tool to monitor the rear fog lamp switch input in the auxiliary body control module (XBCM) data list while depressing the switch several times.

Does the scan tool parameter change from Active to Inactive?

Go to Step 6

Go to Step 5

5

Test for an open or high resistance in the rear fog lamp switch signal circuit and fog lamp switch ground circuit. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 11

Go to Step 10

6

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

Did you complete the repair?

Go to Step 11

Go to Step 7

7

Inspect for poor connections at the harness connector of the auxiliary body control module (XBCM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 11

Go to Step 9

8

Clean the socket terminals and/or replace the rear fog lamp bulb. Refer to Rear Fog Lamp Bulb Replacement .

Did you complete the repair?

Go to Step 11

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9

Replace the XBCM. Refer to Control Module References for replacement, setup, and programming.

Did you complete the replacement?

Go to Step 11

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10

Replace the headlamp switch. Refer to Headlamp Switch Replacement .

Did you complete the repair?

Go to Step 11

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11

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 3