2000 GMC Sierra 1500 Pickup Owner's Manual - Page 134

yellowblue Compass Operation Press the COMP switch once briefly to turn the compass on or off. When the ignition and the compass feature are on, the compass will show two character boxes for approximately two seconds. After two seconds, the mirror will display the compass heading. When cleaning the mirror, use a paper towel or similar material dampened with glass cleaner. Do not spray glass cleaner directly on the mirror as that may cause the liquid cleaner to enter the mirror housing. Compass Calibration The compass may need calibration if: In order to calibrate, the letter "C" must be displayed in the mirror compass windows. If "C" is not displayed, push in the "COMP" button for approximately eight seconds or until the letter "C" is 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. Compass Variance The compass 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. 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 2-56