GM Service Manual Online
For 1990-2009 cars only

Step

Action

Yes

No

Schematic Reference: Headlights/Daytime Running Lights (DRL) 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 flash to pass (FTP) is inoperative.

Does the FTP operate normally?

Go to Testing for Intermittent Conditions and Poor Connections

Go to Step 3

3

Do the high beam headlamps operate normally?

Go to Symptoms - Lighting Systems

Go to Step 4

4

  1. Turn the key to RUN with the engine OFF.
  2. Connect a fused jumper from ground to the headlamp switch flash to pass signal terminal of the headlamp dimmer switch connector.

Do the high beam headlamps illuminate?

Go to Step 6

Go to Step 5

5

Test the headlamp switch flash to pass signal circuit for an open or high resistance. 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 dimmer switch. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 10

Go to Step 9

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 8

8

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

Did you complete the replacement?

Go to Step 10

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9

Replace the headlamp dimmer switch. Refer to Turn Signal Multifunction Switch Replacement .

Did you complete the repair?

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