GM Service Manual Online
For 1990-2009 cars only

If the vehicle has the memory package, the passenger and/or driver outside mirrors tilt to a preselected position when the vehicle is in REVERSE (R). This lets the driver view the curb while parallel parking.

The mirror(s) return to its original position when the vehicle is shifted out of REVERSE (R), or the ignition is turned to LOCK/OFF.

This feature can be turned on or off through the Driver Information Center (DIC). See "Park Tilt Mirrors" under DIC Vehicle Customization for more information.