GM Service Manual Online
For 1990-2009 cars only

Step

Action

Normal Result(s)

Abnormal Result(s)*

1

  1. Turn the ignition switch to the OFF position.
  2. Do not set the park brake.

  3. For automatic transmission, place the transmission in PARK.
  4. For manual transmission, place the transmission in NEUTRAL. Block the wheels.

  5. Place the headlamp switch in the AUTO position.
  6. Ensure that a sufficient amount of light reaches the ambient light sensor. Use a trouble light if necessary.
  7. Turn the ignition switch to the ON position. Do not start the engine.
    • The DRLs are ON.
    • All of the other exterior lamps are OFF.
    • Headlamps On in Daylight Conditions

2

  1. Turn the ignition switch to the OFF position.
  2. Set the park brake.
  3. For automatic transmission, place the transmission in DRIVE, then in PARK.
  4. For manual transmission, place the transmission in NEUTRAL. Block the wheels.

  5. Place headlamp switch in the AUTO position.
  6. Turn the ignition switch to the ON position. Do not start the engine.
    • The DRLs are OFF.
    • All of the other exterior lamps are OFF.

Headlamps, DRL On With Park Brake Applied

3

  1. Cover the ambient light sensor in order to prevent any light from reaching the sensor.
  2. For automatic transmission, place the transmission in DRIVE, then in PARK.
  3. For manual transmission, place the transmission in NEUTRAL. Block the wheels. Do not set the park brake.

  4. Place headlamp switch in the AUTO position.
  5. Turn the ignition switch to the ON position. Do not start the engine.
    • The DRLs are OFF.
    • The headlamps are ON.
    • All of the other exterior lamps are ON.

4

Place the headlamp switch in the HEAD position.

    • The DRLs are OFF.
    • The headlamps are ON.
    • All of the other exterior lamps are ON.

*Refer to the appropriate symptom diagnostic table for the applicable abnormal result.