2006 GMC Envoy Owner's Manual - Page 11

To heat only the seatback, press the vertical button with the heated seatback symbol. An indicator light on the button will come on to designate that only the seatback is being heated. Additional presses will cycle through the heat levels for the seatback only. The feature will shut off automatically when the ignition is turned off. {CAUTION: If the seatback is not locked, it could move forward in a sudden stop or crash. That could cause injury to the person sitting there. Always push and pull on the seatback to be sure it is locked. If the seats have manual reclining seatbacks, the lever used to operate them is located on the outboard side of the seats(s). Reclining Seatbacks Manual Reclining Seatbacks {CAUTION: 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. 1-5