GMC 2003 Sierra - Manual (Page 140)

The dectnochromic (sell dimnning) nimor iunction is
(urnod on automaUcalty each time ihe ii^niiion i& started^
To Dperale the eleclrochnomic tniiror rtn ihe following:
1, Make sare The green Indlcalof lighit, locatEd to
Ihe left of the on/oM button, is lit. If il's not, press
and hold the on.'olf button tor approx!nr>at
0 ly
Six secoods unhl the green light comes on,
Indiicating that the mimor is Jn electTOchromic (self
dimming) mode.
2. Turn off Uie elecTrochramie mirror Tunchon by
pressing and holding the orVotf button for
approximately six seconds unlil the green indicator
light lurns ofi,
Compass Variance
The miirror is sei in zone eight upon 'leaving the factory.
It will he necessary to adjust the compass fo
cainpensate for compass variance if you live outside of
zone eighl, Under certain circumstances, as during a
long distance cross-country trip, it will be necessary Eo
adjust for compass variance Compass variance is
the difference between earth's magnetic north artd true
geographic north, if not adjusted to account for
compass vanance, your compass could give false
readings.
Electrochromic Miirror Operation
1. Find your curreni location and variance zone
number on the faJtowing zone map,
To adjust for compass variance do the foil owing:
2. Priest and hold the orVoH button until a 2 and a
zone number appears in the display. The compass
is now in zone made.
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