GMC Hummer H3 2008 Owner's Handbook Manual page 118

Compass Variance
Compass variance is the difference
between the earth's magnetic
north and the true geographic
north. Your vehicle's compass
should be pre-set to your zone.
If your vehicle is taken outside this
zone, it may be necessary to adjust
the compass to compensate for
variance.
Section 1
To adjust for compass variance:
1. Find your current location and
zone number on the variance
zone map.
2. With the ignition on and the
engine off, press and hold the
button for several seconds
until ZONE or a zone number
appears in the display. Release
the button.
3. Press the button again until
the correct zone number
appears in the display. The dis-
play will show a compass
direction within a few
seconds.
4. Calibrate the compass.
See "Compass Calibration" ear-
lier in this section for more
information.
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