GMC Yukon Owner's Manual page 163

Express-Down/Up Windows
Windows with the express feature allow the windows to
be raised and lowered all the way without holding the
switch.
Press or pull the switch fully and release it to activate
the express feature.
The express mode can be canceled at any time by
briefly pressing or pulling the switch.
Express Window Anti-Pinch Feature
If any object is in the path of the window when the
express up is active, the window will stop at the
obstruction and auto reverse to a preset factory
position. Weather conditions such as severe icing
may also cause the window to auto reverse.
The window will return to normal operation once
the obstruction or condition is removed.
Express Window Anti Pinch Override
WARNING:
If express override is activated, the window will
not reverse automatically. You or others could
be injured and the window could be damaged.
Before you use express override, make sure
that all people and obstructions are clear of the
window path.
In an emergency, the anti pinch feature can be
overridden in a supervised mode. Hold the window
switch all the way up to the second position.
The window will rise for as long as the switch is
held. Once the switch is released, the express
mode is re activated.
In this mode, the window can still close on an object in
its path. Use care when using the override mode.
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