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 high beam headlamps are inoperative.

Do the high beam headlamps operate normally?

Go to Testing for Intermittent Conditions and Poor Connections

Go to Step 3

3

Is only one high beam headlamp inoperative?

Go to Step 4

Go to Step 5

4

  1. Inspect the inoperative bulb for an open filament and connector for poor terminal contact and replace/repair as necessary. Refer to Headlamp Bulb Replacement or Wiring Repairs .
  2. If no problem is found, repair the open, high resistance or short to ground in the high beam headlamp supply voltage circuit or ground circuit to the inoperative lamp. Refer to Circuit Testing and Wiring Repairs .

Did you complete the repair?

Go to Step 13

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5

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

Did you find and correct a condition?

Go to Step 13

Go to Step 6

6

  1. Place the headlamp switch in the HEAD position.
  2. Connect a fused jumper from ground to the headlamp dimmer switch signal terminal of the headlamp dimmer switch connector.

Do the high beam headlamps illuminate?

Go to Step 8

Go to Step 7

7

Connect a fused jumper from ground to the high beam headlamp relay control circuit terminal at the high beam headlamp relay in the underhood fuse block.

Do the high beam headlamps illuminate?

Go to Step 9

Go to Step 11

8

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 13

Go to Step 12

9

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 13

Go to Step 10

10

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

Did you complete the replacement?

Go to Step 13

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11

Replace the high beam headlamp relay. Refer to Relay Replacement .

Did you complete the repair?

Go to Step 13

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12

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

Did you complete the repair?

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