GM Service Manual Online
For 1990-2009 cars only

Step

Action

Yes

No

Schematic Reference: Exterior Lights Schematics

Connector End View Reference: Lighting Systems Connector End Views or Computer/Integrating Systems Connector End Views in Computer/Integrating 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

Verify that the park, license and tail lamps are always ON.

Do the park, license and tail lamps operate normally?

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

Go to Step 3

3

Remove the park lamp relay.

Do the park lamps turn OFF?

Go to Step 4

Go to Step 9

4

  1. Ensure that the headlamp switch is in the OFF position.
  2. Test for a ground signal at the park lamp relay control circuit terminal in the body fuse block. Refer to Circuit Testing in Wiring Systems.

Is a ground signal present?

Go to Step 5

Go to Step 10

5

Use the scan tool to view the body control module (BCM) parklamp switch input data.

Does the scan tool display INACTIVE?

Go to Step 8

Go to Step 6

6

Test for a short to ground in the park lamp switch on signal circuit. Refer to Circuit Testing Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 13

Go to Step 7

7

Inspect for poor connections at the harness connector of the headlamp switch. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 13

Go to Step 11

8

Inspect for poor connections at the harness connector of the BCM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 13

Go to Step 12

9

Repair the short to voltage in one of the following circuits. Refer to Wiring Repairs in Wiring Systems:

    • Front park lamp supply voltage
    • Trailer park lamps supply voltage
    • Right rear park lamps supply voltage
    • Left rear park lamps supply voltage
    • Rear park lamps supply voltage

Did you complete the repair?

Go to Step 13

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10

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

Did you complete the repair?

Go to Step 13

--

11

Replace the headlamp switch. Refer to Headlamp Switch Replacement .

Did you complete the repair?

Go to Step 13

--

12

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 13

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13

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 3