GMC SIERRA CK2 1999 Owner's Manual page 123

Electrochromic Inside Rearview Mirror
with Compass (If Equipped)
Your vehicle may have an electrochromic inside
rearview mirror.
When on, an electrochromic mirror automatically dims
to the proper level to minimize glare from lights behind
you after dark.
The mirror also includes an eight
in the upper right corner of the mirror face. When on,
the compass automatically calibrates as the vehicle
is driven.
-
point compass display
Mirror Operation
The right side of the switch located at the bottom of
the mirror turns the electrochromic mirror on and off.
The AUTO LED 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.
yellowblue
2-45