1999 Chevrolet Tahoe Owner's Manual - Page 115

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 If, after two 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. If the letter "C" should ever appear in the compass window, the mirror may need calibration. The mirror 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. 2-45