2010 GMC Sierra 1500 Crew Cab Owner's Manual - Page 46

Front Seats Manual Seats { WARNING: You can lose control of the vehicle if you try to adjust a manual driver's seat while the vehicle is moving. The sudden movement could startle and confuse you, or make you push a pedal when you do not want to. Adjust the driver's seat only when the vehicle is not moving. Pull the head restraint up to raise it. To lower the head restraint, press the button, located on the top of the seatback, and push the restraint down. Push down on the head restraint after the button is released to make sure that it is locked in place. The head restraints are not designed to be removed. The rear seat has head rests that can be adjusted up and down. 2-4