GM Service Manual Online
For 1990-2009 cars only

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Action

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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 ON the ignition, with the engine OFF.
  2. Turn the front fog lamps ON and OFF.

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

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

Go to Step 4

Go to Step 7

4

  1. Turn OFF the front fog lamps.
  2. With a scan tool, observe the Fog Lamp Relay Cmd. parameter in the BCM lighting data list.

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

Go to Step 5

Go to Step 10

5

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

Do the front 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 front fog lamp relay control voltage supply circuit at the underhood fuse block and ground.
  3. Turn OFF the front fog lamps.
  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 Front Fog Lamp Switch parameter in the BCM lighting data list.

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

Go to Step 11

Go to Step 9

8

Locate and repair a short to voltage in the front 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 10

9

Locate and repair a short to ground in the front 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 FRT 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 19

Go to Step 18

13

Locate and repair a short to voltage in the front 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 harness connector of the underhood fuse 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 Body Control Module Replacement 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 underhood fuse block. Refer to Underhood Electrical Center or Junction Block Replacement in Wiring Systems.

Did you complete the replacement?

Go to Step 19

--

18

Replace the FRT FOG LP 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