GM Service Manual Online
For 1990-2009 cars only

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Action

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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 Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

2

  1. Turn the ignition to the ON position, 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 in Wiring Systems

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 solenoid switched voltage supply circuit.

Does the test lamp illuminate?

Go to Step 13

Go to Step 5

5

Test the high beam solenoid switched voltage supply circuit for a short to ground, open or a poor connection. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 18

Go to Step 15

6

Place the headlamp switch to the FTP position.

Do the high beam headlamp illuminate?

Go to Step 10

Go to Step 7

7

  1. Remove the high beam relay.
  2. Install a 10A fused jumper between battery positive voltage supply and the high beam switched voltage supply circuit.

Do the high beam headlamps illuminate?

Go to Step 8

Go to Step 15

8

  1. Using a test lamp connected between the high beam relay coil side voltage supply circuit and the high beam relay control circuit.
  2. Turn the ignition to the ON position.
  3. Turn the headlamps to the HEAD position.
  4. Turn the headlamp dimmer switch to the HIGH position.

Does the test lamp illuminate?

Go to Step 12

Go to Step 9

9

Test for a poor connection, an open or a short to battery positive voltage in the headlamp high beam relay control circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 18

Go to Step 16

10

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

Did you find and correct the condition?

Go to Step 18

Go to Step 11

11

  1. Disconnect the 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.

Does the test lamp illuminate?

Go to Step 16

Go to Step 14

12

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

Does the high beam headlamps operate normally?

Go to Step 18

Go to Step 15

13

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

Did you complete the replacement?

Go to Step 18

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14

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

Did you complete the replacement?

Go to Step 18

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15

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

Did you complete the replacement?

Go to Step 18

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16

Inspect for poor connections at the BCM. 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 18

Go to Step 17

17

Important:: Perform the setup procedure for the BCM. Refer to Body Control Module (BCM) Programming/RPO Configuration in Computer/Integrating Systems.

Replace the BCM. Refer to Body Control Module Replacement in Computer/Integrating Systems.

Did you complete the replacement?

Go to Step 18

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18

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2