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 in Wiring 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

  1. Turn the headlamp switch to the OFF position.
  2. Turn the rear fog lamp switch to the OFF position.

Are the rear fog lamps ON?

Go to Step 3

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

3

Disconnect the rear fog lamp relay.

Are the rear fog lamps still ON?

Go to Step 13

Go to Step 4

4

Using a test lamp connected to battery positive voltage, probe the control circuit of the rear fog lamp relay connector.

Does the test lamp illuminate?

Go to Step 5

Go to Step 9

5

  1. Disconnect the rear fog lamp module connector.
  2. Probe the control circuit of the rear fog lamp relay connector with a test lamp that is connected to battery voltage.

Does the test lamp illuminate?

Go to Step 12

Go to Step 6

6

Using a test lamp connected to battery positive voltage, probe the fog lamp switch signal circuit of the rear fog lamp module connector.

Does the test lamp illuminate?

Go to Step 7

Go to Step 10

7

  1. Disconnect the rear fog lamp switch connector.
  2. Using a test lamp connected to battery positive voltage, probe the fog lamp switch signal circuit of the rear fog lamp module connector.

Does the test lamp illuminate?

Go to Step 11

Go to Step 8

8

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 in Wiring Systems.

Did you find and correct the condition?

Go to Step 17

Go to Step 15

9

Inspect for poor connections at the harness connector of the rear fog lamp relay . Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 17

Go to Step 14

10

Inspect for poor connections at the harness connector of the rear fog lamp module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 17

Go to Step 16

11

Repair a short to ground in the signal circuit of the rear fog lamp switch. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 17

--

12

Repair a short to ground in the control circuit of the rear fog lamp relay . Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 17

--

13

Repair the short to battery positive voltage in the supply voltage circuit of the rear fog lamps. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 17

--

14

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

Is the repair complete?

Go to Step 17

--

15

Replace the rear 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 17

--

16

Replace the rear fog lamp module.

Did you complete the repair?

Go to Step 17

--

17

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2