2002 Chevrolet Tahoe Owner's Manual - Page 139

Compass Calibration The compass may need calibration if one of the following occurs: 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 you live 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. To adjust for compass variance: 1. Use the COMP button located at the bottom of the mirror. 2. Press and hold the COMP button for three seconds until a zone number appears in the display. 3. Find your current location and variance zone number on the following zone map. D After 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. and the compass zone variance is set correctly. D The compass does not display the correct heading In order to calibrate, the letters CAL must be displayed in the mirror compass windows. If CAL is not displayed, push in the COMP button for approximately eight seconds or until the letters CAL are displayed. The compass can be calibrated in one of two ways: D Drive the vehicle in circles at five mph (8 km/h) or less until the display reads a direction, or D drive the vehicle on your everyday routine and after several turns the compass will become calibrated and will display a direction. 2-53