GM Service Manual Online
For 1990-2009 cars only

Step

Action

Yes

No

Schematic Reference: Headlights/Daytime Running Lights (DRL) Schematics

1

Did you perform the Lighting System Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - Lighting Systems

2

  1. Turn ON the headlamps.
  2. Ensure that the headlamp dimmer switch is in the HIGH position.

Do the high beams illuminate?

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

Go to Step 3

3

Is only one high beam headlamp inoperative?

Go to Step 9

Go to Step 4

4

  1. Leave the headlamp switch in the HEAD position.
  2. Disconnect the headlamp dimmer switch.
  3. Connect a fused jumper between the high beam relay supply voltage circuit of the headlamp dimmer switch and the control circuit of the high beam relay.

Do the high beams illuminate?

Go to Step 6

Go to Step 5

5

Install a fused jumper across the battery positive voltage supply circuit and the switched high beam voltage supply circuit.

Do the high beams illuminate?

Go to Step 7

Go to Step 8

6

Inspect for a poor connection at the harness connector of the headlamp 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 14

Go to Step 10

7

Inspect for a poor connection at the harness connector of the high beam relay. 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 14

Go to Step 11

8

Inspect for a poor connection at the harness connectors of the underhood fuse block. 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 14

Go to Step 12

9

Inspect the inoperative high beam headlamp power supply and ground circuit for a high resistance or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 14

Go to Step 13

10

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 replacement?

Go to Step 14

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11

Replace the high beam relay. Refer to Relay Replacement in Wiring Systems.

Did you complete the replacement?

Go to Step 14

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12

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

Did you complete the repair?

Go to Step 14

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13

Replace the inoperative high beam headlamp. Refer to Headlamp Assembly or Headlamp Bulb Replacement .

Did you complete the replacement?

Go to Step 14

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14

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 3