GM Service Manual Online
For 1990-2009 cars only

Step

Action

Yes

No

Schematic Reference: Fog Lights Schematics

Connector End View Reference: Master Electrical Component List

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

  1. Turn the ignition to the ON position.
  2. Press the fog lamp switch to the OFF position.

Are the fog lamps OFF?

Go to Testing for Intermittent Conditions and Poor Connections

Go to Step 3

3

Using a scan tool, command the fog lamps OFF.

Are the fog lamps illuminated?

Go to Step 5

Go to Step 4

4

  1. Disconnect the scan tool.
  2. Disconnect the fog lamp switch.
  3. Connect a 3-amp fused jumper wire between the front fog lamp switch signal circuit and a good ground.

Are the fog lamps illuminated?

Go to Step 6

Go to Step 9

5

Test the fog lamp voltage supply circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 13

Go to Step 7

6

Test the front fog lamp switch signal circuit for the following:

    • An open
    • A high resistance
    • A short to ground

Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 13

Go to Step 8

7

Inspect for poor connections at the harness connector of the underhood fuse block. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 13

Go to Step 10

8

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

Did you find and correct the condition?

Go to Step 13

Go to Step 11

9

Inspect for poor connections at the harness connector of the fog lamp switch. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 13

Go to Step 12

10

Replace the underhood fuse block. Refer to Underhood Electrical Center or Junction Block Bracket Replacement .

Did you complete the replacement?

Go to Step 13

--

11

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

Did you complete the replacement?

Go to Step 13

--

12

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

Did you complete the replacement?

Go to Step 13

--

13

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2