Chevrolet 2003 Venture Owner's Manual page 242

Compass Variance
Compass variance is the difference between magnetic
north and geographic north. In some areas of the
country, the difference is great enough to cause the
compass to give false readings. If this occurs, the
compass variance must be set.
Setting the Variance
Turn the ignition on and cycle the DIC to the
compass/temperature mode. Press both the E/M and
MODE buttons simultaneously for approximately
five seconds. The last entered variance zone number
will be displayed. Press the E/M button until the proper
variance number, as shown on the map, is showing.
Press the MODE button to set the new variance
zone and resume normal operation.
The display will show all the display segments briefly to
acknowledge the change in the zone number.
Automatic
Compass
Calibration
The compass is self-calibrating, which eliminates the
need to manually set the compass. When the vehicle is
new, the calibration process may not be complete. In
these cases the calibration symbol C will be displayed
where the compass reading is normally displayed.
To calibrate the compass, in an area free from large
metal objects, make three 360" turns. The calibration
symbol will turn off and the compass reading will
be
displayed.
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