GM Service Manual Online
For 1990-2009 cars only

Step

Action

Yes

No

Schematic Reference: Exterior Lights Schematics

1

Did you review the exterior lighting operation and perform the necessary inspections?

Go to Step 2

Go to Symptoms - Lighting Systems

2

Place the headlamp switch in the OFF position.

Are the park lamps OFF?

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

Go to Step 3

3

Remove the tail lamp relay.

Do the park lamps remain illuminated?

Go to Step 6

Go to Step 4

4

Probe the tail lamp relay coil side control circuit with a test lamp that is connected to battery positive voltage.

Does the test lamp illuminate?

Go to Step 5

Go to Step 8

5

  1. Leave the test lamp connected.
  2. Disconnect the headlamp switch.

Does the test lamp remain illuminated?

Go to Step 7

Go to Step 9

6

Repair a short to voltage in the park lamps voltage supply circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 10

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7

Repair a short to ground in the tail lamp relay coil side control circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 10

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8

Replace the tail lamp relay. Refer to

Did you complete the replacement?

Go to Step 10

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9

Replace the headlamp switch. Refer to Headlamp Switch Replacement .

Did you complete the replacement?

Go to Step 10

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10

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 3