GM Service Manual Online
For 1990-2009 cars only

Step

Action

Yes

No

Schematic Reference: Interior Lights Dimming Schematics

Connector End View Reference: Lighting Systems Connector End Views or Data Communication Connector End Views

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

Verify that the headlamp switch on indicator is always ON.

Does the headlamp switch on indicator operate properly?

Go to Testing for Intermittent Conditions and Poor Connections

Go to Step 3

3

Are the headlamps operating properly?

Go to Step 4

Go to Symptoms - Lighting Systems

4

  1. Disconnect the headlamp switch.
  2. Test for a ground signal at the headlamp on indicator control terminal of the headlamp switch connector.

Is a ground signal present?

Go to Step 5

Go to Step 6

5

Test the headlamp on indicator control circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct a condition?

Go to Step 10

Go to Step 7

6

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

Did you find and correct the condition?

Go to Step 10

Go to Step 8

7

Inspect for poor connections at the harness connector of the body control module (BCM). Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 10

Go to Step 9

8

Replace the headlamp switch. Refer to Headlamp Switch Replacement .

Did you complete the repair?

Go to Step 10

--

9

Replace the BCM. Refer to Control Module References for replacement, setup, and programming.

Did you complete the replacement?

Go to Step 10

--

10

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 3