GMC 2005 Canyon - Manual (Page 120)

Compass Variance
Compass variance is the difference between earth’s
magnetic north and true geographic north. If the mirror
is not adjusted for compass variance, your compass
could give false readings.
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 you live outside
zone eight. Under certain circumstances, such as a long
distance, cross-country trip, it will be necessary to
adjust the compass variance.
To adjust for compass variance, do the following:
1. Find your current location and variance zone
number on the zone map that follows.
2. Press and hold the left map light button until a zone
number appears on the display.
3. Once the zone number appears on the display,
press the on/off button quickly until you reach
the correct zone number. Stop pressing the button
and the mirror will return to normal operation.
If C appears in the compass window, the compass
may need calibration. See “Compass Calibration”
listed previously.
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