Oldsmobile 2003 Bravada Owner's Manual page 96

Compass Calibration
Press and hold the on/off button down for nine seconds
to activate the compass calibration mode. "CAL" will
be displayed in the compass window on the mirror.
The mirror can be calibrated in one of two ways:
Drive the vehicle in circles at 5 mph (8 km/h) or less
drive the vehicle on your everyday routine. (This
until the display shows "CAL", or
method may take longer to calibrate.)
Compass Variance
Compass variance is the difference between earth's
magnetic north and true geographic north. The mirror is
set to 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 during a
long distance cross-country trip, it will be necessary to
adjust for compass variance. If not adjusted to
account for compass variance, your compass could give
false readings.
To adjust for compass variance, do the following:
1. Find your current location and variance zone
number on the map.
2. Press and hold the on/off button for six seconds.
Release the button when "ZONE" is displayed.
The number shown is the current zone number.
3. Scroll through the zone numbers that appear in the
compass/temperature window on the mirror by
pressing the on/off button. Once you find your zone
number, release the button. After about four
seconds, the mirror will return to the compass
display, and the new zone number will be set.
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