Cadillac 2007 - Manual (Page 147)

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.
4. Calibrate the compass as described next.
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