GMC Sierra 2000, Owner'S Manual

Page: 117 / 426

2-49
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 you live outside 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,
your compass could give false readings.
To adjust for compass variance:
1. Press and hold the COMP button (located at the
bottom of the mirror) for three seconds until a zone
number appears in the display.
2. Find your current location and variance zone number
on the following zone map.
3. Press the COMP button on the bottom of the mirror
until the new zone number appears in the display.
After you stop pressing the button in, the display will
show a compass direction within a few seconds.