2007 Chevrolet Tahoe Owner's Manual - Page 167

Automatic Dimming Mirror Operation O: Press this button to turn the automatic dimming feature on or off. The indicator light to the left of the button will turn on to indicate when the feature is on. Once the mirror is turned off, it will remain off until it is turned back on, or until the vehicle is restarted. • The compass does not display the correct heading and the compass zone variance is set correctly. In order to calibrate, CAL must be displayed in the mirror compass windows. If CAL is not displayed, push in the compass/temperature button for approximately nine seconds or until CAL is displayed. 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 Operation Press the compass/temperature button once briefly to turn the display on or off. Compass Calibration The compass may need calibration if one of the following occurs: • If CAL is displayed while driving in the vehicle. • After approximately five seconds, the display does not show a compass heading, N for North, for example, there may be a strong magnetic field interfering with the compass. Such interference may be caused by a magnetic antenna mount, magnetic note pad holder, or a similar magnetic item. Compass Variance The mirror is set in zone eight upon leaving the factory. It will be necessary to adjust the compass to compensate for compass variance if the vehicle is outside zone eight. Under certain circumstances, as during a long distance cross-country trip, it will be necessary to adjust for compass variance. Compass variance is the difference between earth's magnetic north and true geographic north. If not adjusted to account for compass variance, your compass could give false readings. 167