GM Service Manual Online
For 1990-2009 cars only

If the vehicle has this mirror, while sitting in a comfortable driving position, adjust the mirror so you can see clearly behind the vehicle. Grip the mirror in the center to move it up or down and side to side. The day/night adjustment, located at the bottom of the mirror, allows adjustment to lessen glare from the lamps behind you. Pull the lever for daytime use; push it for night use.