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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 nd 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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Page 154 of 594

Automatic Dimming Rearview
Mirror with OnStar
®, Compass and
Temperature Display
Your vehicle may have this feature. When on, an
automatic dimming mirror automatically dims to the
proper level to minimize glare from lights behind
you after dark.
The mirror also includes a dual display in the upper
right corner of the mirror face. The compass reading and
the outside temperature will both appear in the display
at the same time.
P(On/Off):This is the on/off button.
Temperature and Compass Display
Press the on/off button, located to the far left, brie y to
turn the compass/temperature display on or off.
If the display reads CAL, you will need to calibrate the
compass. For more information on calibration, see below.
To adjust between Fahrenheit and Celsius do the
following:
1. Press and hold the on/off button for
approximately four seconds until either a
ashing F or C appears.2. Press the button again to change the display to the
desired unit of measurement. After approximately
four seconds of inactivity, the new unit will be locked
in and the compass/temperature display will return.
If an abnormal temperature reading is displayed for an
extended period of time, please consult your dealer.
Under certain circumstances, a delay in updating
the temperature is normal.
Automatic Dimming Mirror Operation
The automatic dimming mirror function is turned
on automatically each time the ignition is started. To
operate the automatic dimming mirror, do the following:
1. Make sure the green indicator light, located to the left
of the on/off button, is lit. If it’s not, press and hold the
on/off button for approximately six seconds until the
green light comes on, indicating that the mirror is in
automatic dimming mode.
2. Turn off the automatic dimming mirror function
by pressing and holding the on/off button for
approximately six seconds, until the green indicator
light turns off.
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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 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, 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 following zone map.
2. Press and hold the on/off button until a Z and a
zone number appear 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 below.
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