1997 Buick Riviera Owner's Manual - Page 114

Compass Variance Variance is the difference between magnetic north and geographic north.In some areas, the difference between the two can be great enough to cause compass false f to readings. I this happens, follow these instructions set the variance for your particular location: 1 Find your location the -me map. Note your . on zone number. 2. Hold inthe CAL switch (onthe bottom of the mirror housing) for five seconds until the current zone entr number appears onthe display. To hold in the CAL switch, insert a paperclip into the small holeon the bottom of the mirror housing. 3. Repeatedly pressthe CAL switch untilthe number for the new zone is displayed. entry \ Once the desired zone number is displayed, stop pressing theCAL switch and the display will show compass direction within a few seconds. 2-53