GM Service Manual Online
For 1990-2009 cars only

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Action

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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 Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

2

  1. Turn ON the ignition, with the engine OFF.
  2. Turn ON the low beam headlamps.
  3. Turn the rear fog lamps ON and OFF.

Do 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. Place the rear fog lamp switch in the OFF position.
  4. With a scan tool, observe the Rear Fog Lamp Switch parameter in the body control module (BCM) lighting data list.

Does the scan tool indicate the rear fog lamp switch parameter is Inactive?

Go to Step 4

Go to Step 7

4

With a scan tool, observe the Rear Fog Lamp Relay Cmd. in the BCM lighting data list.

Does the scan tool indicate the rear fog lamp relay Cmd. parameter is Off?

Go to Step 5

Go to Step 10

5

  1. Turn OFF the ignition .
  2. Disconnect the FOG RR relay. Refer to Relay Replacement in Wiring Systems.
  3. Turn ON the ignition, with the engine OFF.

Do the rear fog lamps turn OFF?

Go to Step 6

Go to Step 13

6

  1. Turn OFF the ignition.
  2. Connect a test lamp between the rear fog lamp relay control circuit and the rear FOG RR voltage supply circuit at the I/P relay block.
  3. Turn OFF the rear fog lamp switch.
  4. Turn ON the ignition, with the engine OFF.

Does the test lamp illuminate?

Go to Step 8

Go to Step 12

7

  1. Turn OFF the ignition.
  2. Disconnect the turn signal/multifunction switch.
  3. Turn ON the ignition, with the engine OFF.
  4. With a scan tool, observe the Rear Fog Lamp Switch parameter in the BCM lighting data list.

Does the scan tool indicate the Rear Fog Lamp Switch parameter is Inactive?

Go to Step 11

Go to Step 9

8

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

Did you find and correct the condition?

Go to Step 19

Go to Step 14

9

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

Did you find and correct the condition?

Go to Step 19

Go to Step 10

10

Inspect for poor connections at the harness connector of the BCM. 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 19

Go to Step 15

11

Inspect for poor connections at the harness connector of the turn signal/multifunction 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 19

Go to Step 16

12

Inspect for poor connections at 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 19

Go to Step 18

13

Locate and repair a short to voltage in the rear 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 19

Go to Step 14

14

Inspect for poor connections at the instrument panel (I/P) relay block. 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 19

Go to Step 17

15

Replace the BCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.

Did you complete the replacement?

Go to Step 19

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16

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 19

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17

Replace the I/P relay block.

Did you complete the replacement?

Go to Step 19

--

18

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

Did you complete the replacement?

Go to Step 19

--

19

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2