GM Service Manual Online
For 1990-2009 cars only

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Schematic Reference: Fog Lights Schematics

Connector End View Reference: Master Electrical Component List in Wiring Systems.

1

Did you perform the Lighting System Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - Lighting Systems

2

  1. Turn the ignition to the ON position, with the engine OFF.
  2. Turn the headlamp switch to the HEAD position.
  3. Pull the turn signal lever toward you in order to illuminate the LOW headlamps.
  4. Turn the fog lamp switch to the ON position.

Do both front fog lamps operate?

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

Go to Step 3

3

Is only one front fog lamp inoperative?

Go to Step 12

Go to Step 4

4

  1. Remove the fog lamp relay.
  2. Using a test lamp connected to ground, probe the switch side supply circuit of the fog lamp relay connector.

Does the test lamp illuminate?

Go to Step 5

Go to Step 19

5

Install a fused jumper across the switch side feed circuit and the fog lamps supply voltage circuit of the fog lamp relay connector. Refer to Circuit Testing in Wiring Systems.

Did the fog lamps illuminate?

Go to Step 7

Go to Step 6

6

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

Did you find and correct the condition?

Go to Step 23

Go to Step 19

7

Using a test lamp connected to ground, probe the control circuit of the fog lamp relay connector.

Does the test lamp illuminate?

Go to Step 8

Go to Step 9

8

  1. Insure that the high beam headlamps are OFF.
  2. Using a test lamp connected to battery positive voltage, probe the headlamp high beam voltage supply circuit of the fog lamp relay connector.

Does the test lamp illuminate?

Go to Step 20

Go to Step 17

9

  1. Disconnect the rear window wiper/washer and multifunction switch connector C3.
  2. Using a test lamp connected to ground, probe the park lamp supply voltage circuit of the fog lamp switch.

Does the test lamp illuminate?

Go to Step 10

Go to Step 18

10

  1. Connect a fused jumper between the park lamps supply voltage circuit and the fog lamp relay coil supply circuit of the fog lamp switch connector.
  2. Using a test lamp connected to ground, probe the coil supply circuit of the fog lamp relay connector.

Does the test lamp illuminate?

Go to Step 21

Go to Step 11

11

Test the control circuit of the fog lamp relay for a open, high resistance or a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 23

Go to Step 19

12

  1. Remove the inoperative fog lamp.
  2. Using a test lamp, probe between the fog lamps supply voltage circuit and the ground circuit of the inoperative fog lamps.

Does the test lamp illuminate?

Go to Step 22

Go to Step 13

13

  1. Disconnect the inoperative fog lamp connector.
  2. Using a test lamp connected to ground, probe the supply voltage circuit of the inoperative fog lamp connector.

Does the test lamp illuminate?

Go to Step 14

Go to Step 15

14

Using a test lamp, probe between the ground circuit and the supply voltage circuit of the inoperative fog lamp connector.

Does the test lamp illuminate?

Go to Step 22

Go to Step 16

15

Repair the open or high resistance in the supply voltage circuit of the inoperative fog lamp. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 23

--

16

Repair the open or high resistance in the ground circuit of the inoperative fog lamp. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 23

--

17

Repair the open or high resistance in the headlamp high beam voltage supply of the fog lamp relay. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 23

--

18

Repair the open or high resistance in the parklamp supply voltage circuit of the fog lamp switch. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 23

--

19

  1. Test for poor connections at the junction block - underhood. Refer to Testing for Intermittent Conditions and Poor Connections .
  2. If the connections are OK, replace the junction block - underhood. Refer to Underhood Electrical Center or Junction Block Replacement .

Did you complete the repair?

Go to Step 23

--

20

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

Did you complete the repair?

Go to Step 23

--

21

Replace the fog lamp switch. Refer to Instrument Panel Multifunction Switch Assembly Replacement in Instrument Panel, Gages, and Console.

Did you complete the replacement?

Go to Step 23

--

22

Replace the inoperative front fog lamp. Refer to Front Fog Lamp Replacement .

Did you complete the repair?

Go to Step 23

--

23

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2