See also:

Compass
The vehicle may have a compass in the Driver Information Center (DIC). ...

Cellular and GPS Antennas
Avoid placing items over or near the antenna to prevent blocking cellular and GPS signal reception. Cellular reception is required for OnStar to send remote signals to the vehicle. ...

Adjusting the Brightness and Contrast of the Screen
To adjust the brightness and contrast of the screen, press the MENU button while the rear vision camera image is on the display. Any adjustments made will only affect the rear vision camera screen. ...