GM Service Manual Online
For 1990-2009 cars only

Step

Action

Yes

No

Schematic Reference: Headlights Schematics

1

Did you perform the Lighting Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - Lighting Systems

2

  1. Turn ON the headlamp switch.
  2. Turn ON the high beams.

Do the high beam headlamps operate normally?

Go to Testing for Electrical Intermittents in Wiring Systems

Go to Step 3

3

  1. Disconnect the headlamp dimmer switch connector C201C.
  2. Turn ON the headlamp switch.
  3. Connect a fused jumper wire between the headlamp dimmer switch high beam signal circuit of connector C201C and a good ground.

Do the high beams illuminate?

Go to Step 4

Go to Step 6

4

Connect a test lamp between the dimmer switch ground circuit and battery positive voltage.

Does the test lamp illuminate?

Go to Step 5

Go to Step 7

5

Inspect for poor connections at the engine wiring harness junction block and the dimmer switch. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 9

Go to Step 8

6

Repair the open in the headlamp dimmer switch high beam signal circuit between the engine wiring harness junction block and the dimmer switch. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 9

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7

Repair the open in the headlamp dimmer switch ground circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 9

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8

Replace the headlamp dimmer switch. Refer to Multifunction, Turn Signal, and Hazard Switch Replacement - On Vehicle in Steering Wheel and Column.

Did you complete the repair?

Go to Step 9

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9

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 3