Your vehicle may have an automatic-dimming rearview mirror with a compass and the OnStar® system.

There are three additional buttons for the OnStar® system. See your dealer for more information on the system and how to subscribe to OnStar®. See OnStar® System for more information about the services OnStar® provides.

When turned on, this mirror automatically dims to the proper level to minimize glare from any headlamps behind you after dark.

(On/Off): This is the on/off button for the automatic dimming feature and compass. Press the far left button, located below the mirror face, for up to three seconds to turn the feature on and off. A light on the mirror will be lit while the feature is turned on.

Press the on/off button once to turn the compass on or off.

There is a compass display in the window in the upper right corner of the mirror face. The compass displays a maximum of two characters. For example, "NE" is displayed for north-east.

Press and hold the on/off button down for nine seconds to activate the compass calibration mode. CAL will be displayed in the compass window on the mirror.

The compass can be calibrated by driving the vehicle in circles at 5 mph (8 km/h) or less until the display reads a direction.

Compass variance is the difference between earth's magnetic north and true geographic north. The mirror is set to zone eight upon leaving the factory. It will be necessary to adjust the compass to compensate for compass variance if you live outside zone eight. Under certain circumstances, such as during a long distance cross-country trip, it will be necessary to adjust for compass variance. If not adjusted to account for compass variance, your compass could give false readings.

To adjust for compass variance, do the following:

1. Find your current location and variance zone number on the map.



2. Press and hold the on/off button for six seconds. Release the button when ZONE is displayed. The number shown is the current zone number.
3. Scroll through the zone numbers that appear in the compass/temperature window on the mirror by pressing the on/off button. Once you find your zone number, release the button. After about four seconds, the mirror will return to the compass display, and the new zone number will be set.