GMC 2009 Sierra - Manual (Page 113)

Mirrors
Automatic Dimming Rearview Mirror
with OnStar
® , Compass and
Temperature Display
Your vehicle may have this feature. When on, an
automatic dimming inside rearview mirror automatically
dims to the proper level to minimize glare from lights
behind you after dark.
The mirror also includes a dual display in the upper
right corner of the mirror face. The compass reading and
the outside temperature will both appear in the display
at the same time.
P (On/Off): This is the on/off button.
Temperature and Compass Display
Press the on/off button, located to the far left, briefly to
turn the compass/temperature display on or off.
If the display reads CAL, you will need to calibrate the
compass. For more information on calibration see
“Compass Calibration” following.
To adjust between Fahrenheit and Celsius:
1. Press and hold the on/off button for approximately
four seconds until either a flashing F or C appears.
2. Press the button again to change the display to the
desired unit of measurement. After approximately
four seconds of inactivity, the new unit will be locked
in and the compass/temperature display will return.
If an abnormal temperature reading is displayed for an
extended period of time, please see your dealer.
Under certain circumstances, a delay in updating the
temperature is normal.
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.
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