GMC 2000 Envoy Owner's Manual page 105

Mirrors
Electrochromic Day/Night Inside
Rearview Mirror
This mirror automatically changes to reduce glare from
headlamps behind you. A photocell on the back of
the mirror senses when it is becoming dark outside.
Another photocell built into the mirror surface senses
when headlamps are behind you.
At night, when the glare is too high, the mirror will
gradually darken to reduce glare (this change may take a
few seconds). The mirror will return to its clear daytime
state when the glare is reduced. The mirror will also
return to its clear daytime state when the vehicle is put
into REVERSE (R).
Press the AUTO button at the base of the mirror to turn
on the automatic feature. The button has an indicator
light to show it is on. Press the OFF button to turn the
automatic feature off.
Time Delay
The automatic mirror has a time delay feature which
prevents unnecessary switching from the night back to
the day position. This delay prevents rapid changing of
the mirror as you drive under lights and through traffic.
Cleaning the Photocells
Use a cotton swab and glass cleaner to clean the
photocells when necessary.
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