GMC 2010 Sierra - Manual (Page 288)

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
V
TO CHANGE COMPASS ZONE
displays. Or, if the vehicle does not have DIC
buttons, press the trip odometer reset stem
until CHANGE COMPASS ZONE displays.
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.
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