GMC 2008 Envoy - Manual (Page 116)

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 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 until the
green indicator light turns off.
Temperature and Compass Display
Press the on/off button, located to the far left, briefly 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 until either a
flashing 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 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.
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.
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