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 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. Turn ON the park lamps.
  3. Observe the rear fog lamps.
  4. Turn ON and OFF the rear fog lamps.
  5. Turn OFF the ignition.

Did the rear fog lamps operate properly?

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

Go to Step 3

3

  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. With a scan tool command the Rear Fog Lamps ON from the rear integration module (RIM) Output Control data list.

Do both of the rear fog lamps turn ON?

Go to Step 5

Go to Step 4

4

Are both of the rear fog lamps inoperative?

Go to Step 7

Go to Step 11

5

  1. Position the rear fog lamp switch to the ON position.
  2. With a scan tool, observe the Rear Fog Lamp Switch input parameter in the instrument panel module (IPM) Non -- HVAC data list.

Does the scan tool display ON?

Go to Step 20

Go to Step 6

6

  1. Disconnect the rear fog lamp switch.
  2. Connect a 3-amp fused jumper between the rear fog lamp switch signal circuit and the rear fog lamp switch ground circuit.
  3. With a scan tool observe the Rear Fog Lamp Switch parameter.

Does the scan tool display ON?

Go to Step 19

Go to Step 12

7

  1. Turn OFF the ignition.
  2. Disconnect the RR FOG LP relay. Refer to Relay Replacement in Wiring Systems.
  3. Turn ON the ignition, with the engine OFF.
  4. Probe the RR FOG LP relay control side supply voltage circuit with a test lamp that connected to a good ground.

Does the test lamp illuminate?

Go to Step 8

Go to Step 24

8

Probe the RR FOG LP relay switch side supply voltage circuit with a test lamp that is connected to a good ground.

Does the test lamp illuminate?

Go to Step 9

Go to Step 23

9

  1. Connect a test lamp between the RR FOG LP relay control side supply voltage circuit and the rear fog lamp relay control circuit.
  2. With a scan tool command the Rear Fog Lamps Output Control ON and OFF.

Does the test lamp turn ON and OFF with each command?

Go to Step 10

Go to Step 17

10

  1. Turn OFF the ignition.
  2. Connect a 10-amp fused jumper between the RR FOG LP relay switch side supply voltage circuit and the rear fog lamp supply voltage circuit.
  3. Turn ON the ignition, with the engine OFF.

Do both of the rear fog lamps illuminate?

Go to Step 18

Go to Step 11

11

  1. Turn OFF the ignition.
  2. Remove the inoperative rear fog lamp bulb.
  3. Connect a test lamp between the inoperative rear fog lamps supply voltage circuit and the inoperative rear fog lamp ground circuit.
  4. Turn ON the ignition, with the engine OFF.
  5. Turn ON the rear fog lamp switch.

Does the test lamp illuminate?

Go to Step 22

Go to Step 14

12

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

Did you find and correct the condition?

Go to Step 30

Go to Step 13

13

Test the rear fog switch signal circuit for high resistance, open or short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 30

Go to Step 16

14

Test the rear fog lamps supply voltage circuit for an open, a 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 30

Go to Step 15

15

Test the rear fog lamp ground circuit for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 30

Go to Step 21

16

Test the rear fog 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 30

Go to Step 19

17

Test the rear fog lamp control circuit of the rear RR FOG LP for high resistance, an open or a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 30

Go to Step 21

18

Inspect for poor connections at the RR 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 30

Go to Step 25

19

Inspect for poor connections at the harness connector of the rear 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 30

Go to Step 26

20

Inspect for poor connections at the harness connector of the 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 30

Go to Step 27

21

Inspect for poor connections at the harness connector of the RIM. 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 30

Go to Step 28

22

Inspect for poor connections at the inoperative rear fog lamp bulb. 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 30

Go to Step 29

23

Repair the open or high resistance in the switch side supply voltage circuit of the RR FOG LP relay. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 30

--

24

Repair the high resistance or open in the control side supply voltage circuit of the RR FOG LP relay. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 30

--

25

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

Did you complete the replacement?

Go to Step 30

--

26

Replace the turn signal/multifunction switch. Refer to Turn Signal Multifunction Switch Replacement in Steering Wheel and Column.

Did you complete the replacement?

Go to Step 30

--

27

Important:: Perform the setup procedure for the IPM after IPM replacement.

Replace the IPM. Refer to Rear Integration Body Control Module Replacement in Body Control System.

Did you complete the replacement?

Go to Step 30

--

28

Important:: Perform the setup procedure for the RIM after RIM replacement.

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

Did you complete the replacement?

Go to Step 30

--

29

Replace the inoperative rear fog lamp bulb.

Did you complete the replacement?

Go to Step 30

--

30

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2