GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 1999 🢒 Regal 🢒 Body and Accessories 🢒 Stationary Windows 🢒 Automatic Day-Night Mirrors System Check

Step

Action

Normal Result(s)

Abnormal Result(s)*

1
  1. Cover the ambient light sensor (windshield side) with a dark cloth.
  2. Shine a light on the headlamp sensor (mirror side).
  3. Set the gear selector lever to the REVERSE position.
  1. The mirror gradually darkens.
  2. The mirror gradually lightens to a clear state.

2
  1. Set the gear selector lever to the PARK position.
  2. Remove the cloth and the light.
  1. The mirror gradually darkens.
  2. The mirror lightens to a clear state.

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