Buick 2009 Lucerne Owner's Manual page 198

Compass Zone
Your dealer/retailer will set the correct zone for your
location. If the zone is not set to your location or
you drive out of the area, the variance needs to be
changed to the appropriate zone.
To adjust for compass variance, use the following
procedure:
Compass Variance (Zone) Procedure
1. Do not set the compass zone when the vehicle is
moving. Only set it when the vehicle is in P (Park).
Press the vehicle information button until PRESS
TO CHANGE COMPASS ZONE displays.
3-58
V
2. Find the vehicle's current location and variance
zone number on the map.
Zones 1 through 15 are available.
3. Press the set/reset button to scroll through and
select the appropriate variance zone.
4. Press the trip/fuel button until the vehicle heading,
for example, N for North, is displayed in the DIC.
5. If calibration is necessary, calibrate the compass.
See "Compass Calibration Procedure" following.