Compass Variance - Chevrolet 2008 Colorado Owner's Manual

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 of 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, the compass could give false readings.
To adjust for compass variance:
1. Find your current location and variance zone
number on the following zone map.
2-42
2. Press and hold the on/off button until a Z and a
zone number appears in the display. The compass
is now in zone mode.
3. Keep pressing the on/off button until the desired
zone number appears in the display. Release
the button. After approximately four seconds of
inactivity, the new zone number will be locked
in and the compass/temperature display will return.