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

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

  1. Place the headlamp switch in the ON position.
  2. Place the turn signal multi function dimmer switch in the high beam position.

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

Test the high beam headlamp supply voltage circuit for high resistance, an open or a short to ground. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 15

Go to Step 8

5

  1. Place the headlamp switch in the head lamp position.
  2. Place the turn signal multi function headlamp dimmer switch in the high beam position.
  3. With a scan tool, monitor the High Beam Relay Command data parameter in the body control module (BCM) data list.

Does the scan tool display On?

Go to Step 13

Go to Step 6

6

Test the headlamp turn signal multi function 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 15

Go to Step 7

7

  1. Place the headlamp switch in the head lamp position.
  2. Connect a fused jumper from ground to the turn signal multi function headlamp dimmer switch signal terminal of the turn signal multi function headlamp dimmer switch connector.

Do the high beam headlamps illuminate?

Go to Step 9

Go to Step 10

8

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

Did you find and correct the condition?

Go to Step 15

Go to Step 11

9

Inspect for poor connections at the harness connector of the turn signal multi function headlamp dimmer switch. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 15

Go to Step 14

10

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 15

Go to Step 12

11

Replace the high beam bulb. Refer to Headlamp Replacement .

Did you complete the replacement?

Go to Step 15

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12

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

Did you complete the replacement?

Go to Step 15

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13

Replace the underhood fuse block. Refer to Underhood Electrical Center or Junction Block Replacement .

Did you complete the replacement?

Go to Step 15

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14

Replace the turn signal multi function headlamp dimmer switch. Refer to Turn Signal Multifunction Switch Replacement .

Did you complete the repair?

Go to Step 15

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15

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 3