GM Chevrolet Avalanche - Manual (Page 120)

Compass Variance
The mirror is set in zone eight upon leaving the factory.
It will be necessary to adjust the compass to
compensate for compass variance if the vehicle is
outside zone eight. Under certain circumstances, as
during a long distance cross-country trip, it will be
necessary to adjust for compass variance. Compass
variance is the difference between earth’s magnetic
north and true geographic north. If not adjusted
to account for compass variance, your compass could
give false readings.
To adjust for compass variance:
1. Find your current location and variance zone
number on the following zone map.
2. Press and hold the COMP button for five seconds
until a zone number appears in the display.
3. Press the COMP button on the bottom of the mirror
until the new zone number appears in the display.
After you stop pressing the button, the display
will show a compass direction within a few seconds.
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