Compass Variance
Compass variance is the difference between earth’s magnetic north and true geographic north. The mirror is set to zone eight upon leaving the factory.
It will be necessary to adjust the compass to compensate for compass variance if you live outside zone eight. Under certain circumstances, such as during a long distance cross-country trip, it will be necessary to adjust for compass variance.
If not adjusted to account for compass variance, your compass could give false readings.
To adjust for compass variance, do the following:
1. Find your current location and variance zone number on the following zone map.

2. Press and hold the on/off button for
six seconds. Release the button when
(FOR ZONE) is displayed. The number
shown is the current zone number.
3. Scroll through the zone numbers that appear in
the window on the mirror by pressing the on/off
button. Once you find your zone number,
release the button. After about four seconds,
the mirror will return to the compass display,
and the new zone number will be set.
See also:
Questions and Answers About Safety Belts
Q: Will I be trapped in the vehicle after a crash if I am wearing a safety belt?
A: You could be— whether you are wearing a safety belt or not. Your chance of
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Compass Calibration Procedure
1. Before calibrating the compass, check that the
compass zone is set to the variance zone in
which the vehicle is located. See “Compass
Variance (Zone) Procedure” earlier in this section.
...
Navigation
OnStar navigation requires the Directions and Connections service plan.
Push to receive directions or have
them sent to the vehicle navigation screen. Destinations can also be forwarded to
the v ...
