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

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

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

Do the high beams illuminate?

Go to Testing for Intermittent Conditions and Poor Connections

Go to Step 3

3

Is only one high beam headlamp inoperative?

Go to Step 11

Go to Step 4

4

Using a scan tool, observe the High Beam Switch parameter.

Does the parameter indicate ON?

Go to Step 9

Go to Step 5

5

  1. Reinstall the high beam relay.
  2. Disconnect the multifunction switch.
  3. Connect a jumper between the headlamp dimmer switch high beam signal circuit and ground.

Do the high beam headlamps illuminate?

Go to Step 8

Go to Step 6

6

Test for high resistance or an open in the headlamp dimmer switch high beam signal circuit. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 16

Go to Step 10

7

Test the ground circuit of the multifunction switch C2 Pin D for high resistance or an open. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 16

Go to Step 8

8

Inspect for a poor connection at the harness connector of the multifunction turn signal switch. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 16

Go to Step 12

9

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 .

Did you find and correct the condition?

Go to Step 16

Go to Step 13

10

Inspect for a poor connection at the harness connectors of the body control module (BCM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 16

Go to Step 15

11

Test the inoperative high beam headlamp supply voltage and ground circuit for the following conditions:

    • A high resistance
    •  An open
    •  A short to ground

Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 16

Go to Step 14

12

Replace the multifunction turn signal switch. Refer to Turn Signal Multifunction Switch Replacement .

Did you complete the replacement?

Go to Step 16

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13

Replace the high beam relay. Refer to Relay Replacement .

Did you complete the replacement?

Go to Step 16

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14

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

Did you complete the replacement?

Go to Step 16

--

15

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

Did you complete the replacement?

Go to Step 16

--

16

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2