2004 GMC Envoy Owner's Manual - Page 12

The rear seatback levers are located on the outboard side of the rear seatbacks. Pull the seatback toward you as you lift up on the lever. The head restraint will automatically fold out of the way when the seatback is folded down. To raise the seatbacks, lift up the seatbacks and push on them until they lock into the upright position. Push and pull on the seatbacks to make sure that they are latched securely. Then fold the bottom seat cushion back into place. To return the head restraint to the upright position, reach behind the seat and pull the restraint up until it locks into place. Push and pull on the head restraint to make sure that it is latched securely. 1-6