GM Service Manual Online
For 1990-2009 cars only

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

Connector End View Reference: Master Electrical Component List in Wiring Systems

1

Did you perform the Lighting System Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - Lighting Systems

2

  1. Turn the ignition to the OFF position.
  2. Turn the headlamp switch to the HEAD position.
  3. Place the headlamp dimmer switch in the high beam position.

Are the high beam headlamps operating properly?

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 7

Go to Step 4

4

Place the headlamp dimmer switch in the flash to pass position.

Do the high beam headlamps operate in the flash to pass position?

Go to Step 13

Go to Step 5

5

Place the headlamp dimmer switch in the high beam position.

Does the high beam indicator illuminate?

Go to Step 12

Go to Step 6

6

Test for a high resistance, an open or a short to battery positive voltage in the high beam signal circuit of the headlamp dimmer switch. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 17

Go to Step 13

7

  1. Disconnect the inoperative headlamp.
  2. Using a test lamp connected to ground, probe the battery positive voltage circuit of the inoperative high beam headlamp.

Does the test lamp illuminate?

Go to Step 8

Go to Step 9

8

Connect a test lamp between the headlamp high beam signal circuit and the battery positive voltage circuit of the inoperative high beam headlamp.

Does the test lamp illuminate?

Go to Step 11

Go to Step 10

9

Test for a high resistance or an open in the battery positive voltage circuit of the inoperative headlamp. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 17

Go to Step 12

10

Test for a high resistance or an open in the headlamp high beam signal circuit of the inoperative high beam headlamp. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 17

Go to Step 12

11

Inspect for poor connections at the harness connector of the inoperative headlamp. 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 17

Go to Step 14

12

Inspect for poor connections at the harness connector of the fuse block - underhood. 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 17

Go to Step 15

13

Inspect for poor connections 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 17

Go to Step 16

14

Replace the inoperative headlamp. Refer to Headlamp Assembly or Headlamp Bulb and/or Cornering, Sidemarker, Park, Turn Signal Bulb Replacement .

Did you complete the repair?

Go to Step 17

--

15

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

Did you complete the repair?

Go to Step 17

--

16

Replace the headlamp dimmer switch. Refer to Turn Signal Multifunction Switch Replacement in Steering Wheel and Column.

Did you complete the repair?

Go to Step 17

--

17

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2