2006 GMC Yukon Owner's Manual - Page 110

Liftgate Glass and Liftgate To unlock the liftgate and liftglass from the outside, insert the key into the liftgate lock and turn it counterclockwise. The liftgate glass can then be opened using the button on the liftgate. To lock, turn the key clockwise. All the doors will lock. To open the entire liftgate, lift the handle located in the center of the door. You may also use the remote keyless entry transmitter (RKE), or the power door locks to unlock and lock the liftgate and liftgate glass. Windows {CAUTION: Leaving children, helpless adults, or pets in a vehicle with the windows closed is dangerous. They can be overcome by the extreme heat and suffer permanent injuries or even death from heat stroke. Never leave a child, a helpless adult, or a pet alone in a vehicle, especially with the windows closed in warm or hot weather. 2-14