GMC 2007 Yukon XL Owner's Manual page 159

•
The compass does not display the correct
heading and the compass zone variance
is set correctly.
In order to calibrate, CAL must be displayed in the
mirror compass windows. If CAL is not displayed,
push the on/off button for approximately
12 seconds or until CAL is displayed.
The compass can be calibrated by driving the
vehicle in circles at 5 mph (8 km/h) or less until the
display reads a direction.
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, 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 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.
159