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

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 ON the ignition, with the engine OFF.
  2. Press and hold the brake pedal.
  3. Move the gear select lever out of the PARK position.
  4. Place the headlamp switch in the OFF position.
  5. Move the twilight control out of the OFF position.
  6. Cover the ambient light sensor.
  7. Wait 20 seconds.
  8. Observe the headlamps.
  9. Expose the ambient light sensor to a bright incandescent lamp.
  10. Wait 20 seconds.
  11. Observe the headlamps.
  12. Place the gear select lever in the PARK position.
  13. Turn OFF the ignition.

Did the headlamps switch from low beams to daytime running lamps (DRL) headlamps?

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

Go to Step 3

3

Do the DRL headlamps operate properly?

Go to Step 4

Go to Daytime Running Lamps (DRL) Inoperative

4

Inspect for poor connections at the harness connector of the headlamp 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 6

Go to Step 5

5

Replace the headlamp switch. Refer to Headlamp Switch Replacement .

Is the headlamp switch replacement complete?

Go to Step 6

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6

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2