GM Service Manual Online
For 1990-2009 cars only

Step

Action

Normal Result(s)

Abnormal Result(s)*

1

  1. Turn the light switch to the HEAD position.
  2. Move the dimmer switch to the LO position.

Both the LH and the RH low beam filaments are lit at the normal low beam intensity.

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2

Move the dimmer switch forward to the HI position.

    • Both the LH and the RH low beam filaments turn OFF.
    • Both the LH and the RH high beam filaments are lit.
    • The high beam indicator is lit.

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3

  1. Return the dimmer switch to the LO position.
  2. Turn the light switch to the OFF position.
  3. Start the engine.
  4. Disengage the parking brake.
    • Both the LH and the RH low beam filaments go out.
    • Both the LH and the RH low beam filaments are lit at 80% intensity.

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4

Shut the engine OFF.

All the headlamps turn OFF.

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5

  1. Engage the parking brake.
  2. Turn the ignition to the ON position.

All the headlamps remain OFF.

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6

  1. Disengage the parking brake.
  2. Cover the ambient light sensor.

Both the LH and the RH low beam filaments are lit at the normal low beam intensity.

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7

Turn the ignition switch to the OFF position.

All the headlamps turn OFF.

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