1999 Buick Riviera Owner's Manual - Page 110

yellowblue Mirror Operation 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. Compass Calibration 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: The right side of the button located at the bottom of the mirror turns the electrochromic mirror on and off. To turn on the automatic dimming feature, press MIRROR. To turn off automatic dimming, press MIRROR again. The green indicator light will be illuminated when this feature is active. Compass Operation Press the COMPASS button once 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. D Drive the vehicle in circles at 5 mph (8 km/h) or less until the display reads a direction, or D Drive the vehicle on your everyday routine. 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. 2-48