Chevrolet 2000 Tahoe Owner's Manual page 125

Mirror Operation
The right button located at the bottom of the mirror turns
the electrochromic mirror on and off. The LED, located
to the right of the button, will come on when the
electrochromic mirror is turned on. To turn the mirror on,
press and hold the MIRROR button for three seconds.
The mirror will darken and remain dark until the button is
released. To turn the mirror off, press and release the
MIRROR button.
Compass Operation
Press the COMP switch once briefly to turn the compass
on or off.
When the ignition and the compass feature are on, the
compass will show two character boxes for approximately
two seconds. After two seconds, the mirror will display the
compass heading.
When cleaning the mirror, use a paper towel or similar
material dampened with glass cleaner. Do not spray
glass cleaner directly on the mirror as that may cause
the liquid cleaner to enter the mirror housing.
Compass Calibration
The compass may need calibration if:
D
After five seconds, the display does not show a
compass heading ("N" for North, for example),
there may be a strong magnetic field interfering with
the compass. Such interference may be caused by a
magnetic antenna mount, magnetic note pad holder
or a similar magnetic item.
D
The compass does not display the correct heading
and the compass zone variance is set correctly.
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