Hummer 2006 H2 - Manual (Page 120)

Mirror Operation
When turned on, this mirror automatically dims to the
proper level to minimize glare from any headlamps
behind you after dark.
O (On/Off): This is the on/off button for the automatic
dimming feature and compass. Press the far left button,
located below the mirror face, for up to three seconds
to turn the feature on and off. A light on the mirror will be
lit while the feature is turned on.
Compass Operation
Press the on/off button once to turn the compass on
or off.
There is a compass display in the window in the upper
right corner of the mirror face. The compass displays
a maximum of two characters. For example, “NE”
is displayed for north-east.
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 compass can be calibrated by driving the vehicle in
circles at 5 mph (8 km/h) or less until the display
reads a direction.
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.
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