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 rear fog lamps are inoperative.

Does the rear fog lamp operate normally?

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

Go to Step 3

3

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

Do the park lamps illuminate?

Go to Step 4

Go to Park, License, and Tail Lamps Inoperative

4

Inspect the SEO 1 fuse.

Is the fuse open?

Go to Step 10

Go to Step 5

5

  1. Place the rear fog lamp switch in the ON position.
  2. Remove the rear fog lamp relay.
  3. Test for a ground signal at the rear fog lamp relay control circuit of the rear fog lamp relay. Refer to Circuit Testing in Wiring Systems.

Was a ground signal present?

Go to Step 8

Go to Step 6

6

Test for an open, high resistance, or short to voltage in the following circuits:

    • Rear fog lamp switch signal
    • Rear fog lamp switch ground
    • Rear fog lamp relay control

Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct a condition?

Go to Step 14

Go to Step 7

7

  1. Remove the rear fog lamp switch.
  2. Place a fused jumper between the rear fog lamp switch signal and ground connector terminals.
  3. Test for a ground signal at the rear fog lamp relay control circuit of the rear fog lamp relay. Refer to Circuit Testing in Wiring Systems.

Was a ground signal present?

Go to Step 13

Go to Step 9

8

Test for an open or high resistance in the rear 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 14

Go to Step 12

9

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 14

Go to Step 11

10

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 14

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11

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 14

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12

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

Did you complete the replacement?

Go to Step 14

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13

Replace the rear fog lamp switch. Refer to Rear Fog Lamp Switch Replacement .

Did you complete the repair?

Go to Step 14

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14

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 3