GM Service Manual Online
For 1990-2009 cars only

While sitting in a comfortable driving position, adjust the mirror so you can see clearly behind your vehicle. Hold the mirror in the center to move it up or down and side to side. The day/night control at the bottom of the mirror lets you adjust the mirror to avoid glare from the lamps behind you. Turn the control to the right for nighttime conditions and to the center for daytime conditions.