GM Service Manual Online
For 1990-2009 cars only

If the vehicle has this feature, the passenger's outside mirror will adjust to a preset tilt position while the vehicle is in REVERSE (R) gear. Curb view assist may be useful when you are parallel parking. The mirror will return to normal position when the vehicle is shifted out of REVERSE (R) gear. Automatic mirror movement in either direction will follow a short delay.

You may be able to turn this feature on or off through the Driver Information Center (DIC). See DIC Vehicle Customization .