GM Service Manual Online
For 1990-2009 cars only

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Action

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No

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

Connector End View Reference: Master Electrical Component List

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

  1. Turn ON the ignition, with the engine OFF.
  2. Place the headlamp switch in the HEADLAMP position.
  3. Place the headlamp dimmer switch in the HIGH BEAM position.

Do the HIGH beam headlamps illuminate?

Go to Testing for Intermittent Conditions and Poor Connections

Go to Step 3

3

Are both high beam headlamps inoperative?

Go to Step 6

Go to Step 4

4

  1. Turn the ignition to the ON position.
  2. Turn the headlamps switch to the HEAD position.
  3. Turn the headlamp dimmer switch to the HIGH position.
  4. Disconnect the inoperative high beam headlamp.
  5. Using a test lamp connected to ground, probe the high beam voltage supply circuit.

Does the test lamp illuminate?

Go to Step 13

Go to Step 5

5

Test the high beam voltage supply circuit for the following:

    • An open
    • A poor connection
    • A short to ground

Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 17

Go to Step 11

6

Place the headlamp switch to the FTP position.

Do the high beam headlamp illuminate?

Go to Step 8

Go to Step 7

7

  1. Disconnect BCM connector C1.
  2. Install a 10-amp fused jumper between the headlamp high beam relay control circuit and a good ground.

Do the high beam headlamps illuminate?

Go to Step 12

Go to Step 11

8

Test for the following in the headlamp switch high beam signal circuit:

    • An open
    • A poor connection
    • A short to voltage

Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 17

Go to Step 9

9

  1. Disconnect the body control module (BCM) connector C2.
  2. Using a test light connected to ground, probe the headlamp switch high beam signal circuit.
  3. Place the headlamp switch to the HIGH position.

Do the high beam headlamps illuminate?

Go to Step 12

Go to Step 10

10

Inspect for poor connections at the turn signal/multifunction switch. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 17

Go to Step 14

11

Inspect for poor connections at the fuse block - underhood. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 17

Go to Step 15

12

Inspect for poor connections at the BCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 17

Go to Step 16

13

Repair an open or high resistance in the ground circuit of the inoperative headlamp. Refer to Circuit Testing and Wiring Repairs .

Did you complete the repair?

Go to Step 17

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14

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

Did you complete the replacement?

Go to Step 17

--

15

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

Did you complete the replacement?

Go to Step 17

--

16

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

Did you complete the replacement?

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