GM Service Manual Online
For 1990-2009 cars only

Step

Action

Yes

No

Schematic Reference: Fog Lights Schematics

1

Did you review the Exterior Lighting System Description and Operation and perform the necessary inspections?

Go to Step 2

Go to Symptoms - Lighting Systems

2

  1. Turn the ignition to the ON position.
  2. Turn the rear fog lamp switch OFF.
  3. Turn the headlamp switch to the HEAD position.
  4. Place the headlamp dimmer switch in the LOW position.

Are the rear fog lamps operating properly?

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

Go to Step 3

3

Disconnect the rear fog lamp relay.

Are the rear fog lamps illuminated?

Go to Step 9

Go to Step 4

4

Probe the control circuit of the rear fog lamp relay connector with a test lamp that is connected to battery voltage.

Does the test lamp illuminate?

Go to Step 5

Go to Step 12

5

  1. Connect the rear fog lamp relay.
  2. Disconnect the rear fog lamp switch.

Do the rear fog lamps illuminate?

Go to Step 6

Go to Step 11

6

Disconnect the body control module.

Do the rear fog lamps illuminate?

Go to Step 10

Go to Step 7

7

Probe the signal circuit of the rear fog lamp switch with a test lamp that is connected to battery voltage.

Does the test lamp illuminate?

Go to Step 8

Go to Step 13

8

Repair the short to ground in the signal circuit of the rear fog lamp switch. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 14

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9

Repair the short to battery voltage in the supply voltage circuit of the rear fog lamps. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 14

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10

Repair the short to ground in the rear fog lamp control circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 14

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11

Replace the rear fog lamp switch. Refer to Rear Fog Lamp Switch Replacement .

Did you complete the replacement?

Go to Step 14

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12

Replace the rear fog lamp relay. Refer to Fog Lamp Relay Replacement .

Did you complete the replacement?

Go to Step 14

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13

IMPORTANT: Perform the set up procedure for the body control module (BCM). Refer to Body Control Module (BCM) Programming/RPO Configuration in Body Control System.

Replace the body control module. Refer to Body Control Module Replacement in Body Control System.

Did you complete the replacement?

Go to Step 14

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14

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2