GMC Yukon 2021 Owner's Manual page 32

Pull the tab to turn on the display. Push the
tab to turn it off. When off the mirror is
automatic dimming. Adjust the mirror for a
clear view of the area behind the vehicle
while the display is off.
Press to scroll through the adjustment
options.
Press and to adjust the settings using
the indicators on the mirror. The indicators
will remain visible for five seconds after the
last button activation, and the settings will
remain saved.
Keys, Doors, and Windows
The adjustment options are:
Brightness
Zoom
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