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 inoperative.

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

Are all park, license, and tail lamps inoperative?

Go to Step 6

Go to Step 4

4

Test the supply circuit of the inoperative lamp for high resistance, or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 15

Go to Step 5

5

Test the ground circuit of the inoperative lamp for high resistance, or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 15

Go to Step 11

6

  1. Remove the park lamp relay.
  2. Ensure that the headlamp switch is in the HEAD position.
  3. 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 12

Go to Step 7

7

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

Does the scan tool display ACTIVE?

Go to Step 10

Go to Step 8

8

Test for an open or high resistance in the park lamp switch signal circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 15

Go to Step 9

9

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 15

Go to Step 13

10

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 15

Go to Step 14

11

Replace the inoperative bulb.

Did you complete the replacement?

Go to Step 15

--

12

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

Did you complete the repair?

Go to Step 15

--

13

Replace the headlamp switch. Refer to Headlamp Switch Replacement .

Did you complete the repair?

Go to Step 15

--

14

Replace BCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.

Did you complete the replacement?

Go to Step 15

--

15

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 3