GMC 2006 Sierra - Manual (Page 162)

Passenger Airbag Indicator
The mirror may be equipped with a passenger airbag
indicator on the mirror glass, just above the buttons.
If the vehicle has this feature the mirror will display the
word ON, or an airbag symbol in Canada, when the
passenger airbag is enabled. For more information see
Passenger Sensing System on page 1-81
Cleaning the Mirror
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.
Outside Manual Mirrors
Adjust your outside mirrors so you can just see the side of
your vehicle and have a clear view of objects behind you.
The mirrors can be folded in to enter narrow areas.
The use of hood-mounted air deflectors and add-on
convex mirror attachments may adversely affect mirror
performance.
Outside Camper-Type Mirrors
If your vehicle is equipped with this style camper-type
mirrors, they can be adjusted so you can have a clear
view of the objects behind you.
Pull out the mirror head to extend it for better visibility
when towing a trailer.
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