GM Service Manual Online
For 1990-2009 cars only

Step

Action

Normal Result(s)

Abnormal Result(s)*

1

  1. Place the ignition switch in the RUN position.
  2. Place the gear selector lever in the PARK position.
  3. Place the mirror switch in the MAX position.
  4. Cover the ambient light sensor on the windshield side with a dark cloth.
  5. Shine a light on the headlamp sensor on the mirror side.

The mirrors (inside rearview and outside mirror) gradually darkens.

2

Place the gear selector lever in the REVERSE position.

The mirrors gradually lighten to a clear state.

Mirrors - Automatic Day-Night Inoperative in Reverse

3

Place the gear selector lever in the PARK position.

The mirrors gradually darken.

Mirrors - Automatic Day-Night Inoperative in Reverse

4

  1. Remove the cloth.
  2. Remove the light.

The mirror gradually lightens to a clear state.

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