GM Service Manual Online
For 1990-2009 cars only

Step

Action

Yes

No

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

Connector End View Reference: Lighting Systems Connector End Views or Computer/Integrating Systems Connector End Views in Computer/Integrating Systems or Wiper/Washer Connector End Views in Wiper/Washer 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

Verify that the low beam headlamps are inoperative.

Do the low beam headlamps operate normally?

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

Go to Step 3

3

Is only one low beam headlamp inoperative?

Go to Step 4

Go to Step 5

4

  1. Inspect the inoperative bulb for an open filament and connector for poor terminal contact and replace/repair as necessary. Refer to Headlamp Bulb Replacement or Wiring Repairs in Wiring Systems.
  2. If no problem is found, repair the open, high resistance or short to ground in the low beam headlamp supply voltage circuit or ground circuit to the inoperative lamp. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 19

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5

Does the wiper activated headlamp (WAH) function of the wiper system operate normally?

Go to Step 8

Go to Step 6

6

  1. Block the wheels.
  2. Place the ignition switch in the RUN position with the engine OFF.
  3. Place the gearshift lever in DRIVE.
  4. Place the wiper switch in the LO speed position.
  5. Use the scan tool to monitor the Front Wipers Active input to the body control module (BCM).

Does the scan tool display Yes after approximately 3 cycles of the wiper blades?

Go to Step 14

Go to Step 7

7

Test the windshield wiper switch signal 2 circuit for an open, high resistance, or short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct a condition?

Go to Step 19

Go to Step 13

8

Test the headlamp switch signal and ground circuits for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct a condition?

Go to Step 19

Go to Step 9

9

  1. Place the headlamp switch in the HEAD position.
  2. Connect a fused jumper from ground to the headlamp switch signal terminal of the headlamp switch connector.

Do the low beam headlamps illuminate?

Go to Step 12

Go to Step 10

10

Connect a fused jumper from ground to the headlamp low beam relay control circuit terminal at the headlamp low beam relay (HDM) in the underhood fuse block.

Do the low beam headlamps illuminate?

Go to Step 14

Go to Step 11

11

Test the headlamp low beam relay ground circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct a condition?

Go to Step 19

Go to Step 17

12

Inspect for poor connections at the harness connector of the headlamp switch. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 19

Go to Step 18

13

Inspect for poor connections at the harness connector of the wiper motor cover. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 19

Go to Step 15

14

Inspect for poor connections at the harness connector of the BCM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 19

Go to Step 16

15

Replace the wiper motor. Refer to Windshield Wiper Motor Replacement in Wipers/Washers Systems.

Did you complete the repair?

Go to Step 19

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16

Replace the BCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.

Did you complete the replacement?

Go to Step 19

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17

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

Did you complete the repair?

Go to Step 19

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18

Replace the headlamp switch. Refer to Headlamp Switch Replacement .

Did you complete the repair?

Go to Step 19

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19

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 3