Automatic Dimming Mirror Operation; Compass Variance - GMC Sierra Denali 2006 Owner's Manual

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.

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 appears in the display. The compass
is now in zone mode.
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