GMC 2003 Envoy - Manual (Page 105)

Compass Variance
Compass variance is Iho ditier&nce between garth’s
magnetic north and true geographic north. Tlie mirror is
set JO zone eight upon leaving ihe factory. It wut be
necessary to adjust the compass to connpen&ale
for corripass variance U you live oulside zone sight.
Under certain ciricumslances, such as during a
Jong distance cross-country trip. M wil! be necessary to
adjust for compass variance. If not adjusted to
account for compass variance, your concpass could give
iaise readings.
To adjust for compass vangnee, do the following:
1. Find your current location and variance zone
number on the map.
£. Press and hold ihg on/ofi button for six seconds.
Release the button when "ZONE" is displayed.
The number shown is the current zone number,
3. Scroll ihrough ihe zone numt?efs that appear in the
compassriemperature window on the mirror by
pressing Ihe on/ott button, Once you find your zone
number, roloase the buElon. After about tour
seconds, the mirror will return to the compass
display, and the new zone number will be set.
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