Chevrolet 2002 Impala Owner's Manual page 171

Turn the ignition on and cycle the DIC to the
Compass/Temperature mode. Press the RESET button
for approximately five seconds. The last entered
variance zone number and VAR will be displayed. Press
the MODE button until the proper variance number on
the map is shown. Press the RESET button to set the
new variance zone and resume normal operation.
All the display segments will be illuminated briefly to
acknowledge the change in zone number. A chime will
sound to confirm that the new zone number has been set.
Automatic Compass Calibration
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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 CAL will be displayed, and all segments of
the compass will be illuminated where the compass
reading is normally displayed.
All Segments Illuminated
To calibrate the compass, in an area free from
large metal objects, make one to two 360 _ turns.
The calibration symbol will turn off and the compass
reading will be displayed.
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