GM Service Manual Online
For 1990-2009 cars only

Step

Action

Yes

No

Schematic Reference: Fog Lights Schematics

1

Did you perform the Lighting Systems Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - Lighting Systems

2

  1. Turn ON the ignition, with the engine OFF.
  2. Place the front fog lamp switch in the OFF position.

Do the fog lamps remain illuminated?

Go to Step 3

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

3

With a scan tool, observe the Front Fog Lamp Switch parameter in the Instrument Panel Integration Module (IPM) Non-HVAC data list.

Does the scan tool indicate that the Fog Lamp Switch parameter is OFF?

Go to Step 4

Go to Step 7

4

  1. Turn OFF the ignition.
  2. Disconnect the harness connector of the headlamp switch.
  3. Turn ON the ignition, with the engine OFF.
  4. Connect a test lamp between the fog lamp switch signal circuit and a good ground.

Does the test lamp illuminate?

Go to Step 5

Go to Step 10

5

  1. Turn OFF the ignition.
  2. Disconnect the FOG LP relay.
  3. Turn ON the ignition, with the engine OFF.

Did the fog lamps turn OFF?

Go to Step 6

Go to Step 15

6

Connect a test lamp between the control circuit of the FOG LP relay and the ignition 1 voltage circuit of the FOG LP relay coil.

Does the test lamp illuminate?

Go to Step 8

Go to Step 11

7

  1. Turn OFF the ignition.
  2. Disconnect the harness connector of the headlamp switch.
  3. Turn ON the ignition, with the engine OFF.

Does the scan tool indicate that the Front Fog Lamp Switch parameter is OFF?

Go to Step 12

Go to Step 9

8

Test the control circuit of the FOG LP relay for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 20

Go to Step 14

9

Test the front fog lamp switch signal circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 20

Go to Step 13

10

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

Did you find and correct the condition?

Go to Step 20

Go to Step 13

11

Inspect for poor connections at the FOG LP 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 20

Go to Step 16

12

Inspect for poor connections at the harness connector of the headlamp 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 20

Go to Step 17

13

Inspect for poor connections at the Instrument Panel Integration Module (IPM). 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 20

Go to Step 18

14

Inspect for poor connections at the Dash Integration Module (DIM). 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 20

Go to Step 19

15

Repair a short to voltage in the fog lamp supply voltage circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 20

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16

Replace the FOG LP relay. Refer to Relay Replacement in Wiring Systems.

Did you complete the replacement?

Go to Step 20

--

17

Replace the headlamp switch. Refer to Headlamp Switch Replacement .

Did you complete the replacement?

Go to Step 20

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18

Important:: Perform the setup procedure for the Instrument Panel Integration Module (IPM). Refer to Body Control Module (BCM) Programming/RPO Configuration .

Replace the IPM. Refer to Instrument Panel Module Replacement in Body Control System.

Did you complete the replacement?

Go to Step 20

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19

Important:: Perform the setup procedure for the DIM. Refer to Body Control Module (BCM) Programming/RPO Configuration .

Replace the DIM. Refer to Dash Integration Module Replacement in Body Control System.

Did you complete the replacement?

Go to Step 20

--

20

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2