GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

Schematic Reference: Fog Lights Schematics

Connector End View Reference: Lighting Systems Connector End Views

1

Did you perform the Lighting Systems Diagnostic System Check?

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Go to Step 2

Go to Diagnostic System Check - Lighting Systems

2

Verify that the front fog lamps are inoperative.

Do the front fog lamps operate normally?

--

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

Go to Step 3

3

Is only one front fog lamp inoperative?

--

Go to Step 4

Go to Step 5

4

  1. Inspect the inoperative bulb and socket for an open filament or poor terminal contact and replace as necessary.
  2. If no problem is found, locate and repair the open or high resistance in the front fog lamp supply voltage circuit or ground circuit to the inoperative lamp. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 20

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5

Use the scan tool to inspect for the following related Body Control Module (BCM) Data/ Input Parameters and Output Controls. Refer to Scan Tool Data List for typical values and definitions:

    • Headlamp Ambient Light Sensor
    • Park Brake Switch
    • Auto Headlamps
    • Headlamp Relay Feedback
    • Headlamp Power Relay
    • Park Lamp Relay
    • Front Fog Lamp Relay
    • Front Fog Lamp Switch
    • Park Lamps

Did you find and correct a problem?

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Go to Step 20

Go to Step 6

6

With the engine Off, turn the key to RUN and the headlamp switch to PARK.

Are the park lamps on?

--

Go to Step 7

Go to Symptoms - Lighting Systems

7

Inspect the FOG LP fuse in the underhood fuse block.

Is the fuse open?

--

Go to Step 8

Go to Step 9

8

  1. Remove the front fog lamp relay.
  2. Using a J 39200 digital multimeter (DMM), check for continuity to ground at the battery supply voltage terminal of the front fog lamp relay connector in the underhood fuse block. Refer to Electrical Center Identification Views and Circuit Testing in Wiring Systems.

Is continuity present?

--

Go to Step 13

Go to Step  14

9

  1. Place the front fog lamp switch in the ON position.
  2. Use the J 39200 DMM to check for the specified voltage of the front fog lamp supply voltage circuit at either of the fog lamp sockets. Refer to Circuit Testing in Wiring Systems.

Is the specified voltage present?

B+

Go to Step 15

Go to Step 10

10

Use the scan tool to monitor the front fog lamp switch ON input.

Does the scan tool indicate that the switch is ON?

--

Go to Step 11

Go to Step 12

11

Test the front fog lamp supply voltage and the front fog lamp relay control circuits for an open or high resistance. Refer to Circuit Testing in Wiring Systems.

Was a problem found?

--

Go to Step 16

Go to Step 18

12

Test the front fog lamp switch signal and ground circuits for opens or high resistance. Refer to Circuit Testing in Wiring Systems.

Was a problem found?

--

Go to Step 17

Go to Step 19

13

Repair the short to ground in the associated circuit supplied by the FOG LP fuse. Refer to Power Distribution Schematics in Wiring Systems for further diagnosis.

Did you complete the repair?

--

Go to Step 20

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14

Repair the short to ground in the front 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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15

Repair the open or high resistance in the ground circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 20

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16

Repair the open or high resistance in the front fog lamp supply voltage circuit or the front fog lamp relay control circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 20

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17

Repair the open or high resistance in the front fog lamp switch signal circuit or ground circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 20

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18

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

Did you complete the repair?

--

Go to Step 20

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19

Replace the front fog lamp switch. Refer to Headlamp Switch Replacement .

Did you complete the repair?

--

Go to Step 20

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20

Operate the system in order to verify the repair.

Did you correct the condition?

--

System OK

Go to Step 3