2004 GMC Sonoma Owner's Manual - Page 13

Rear Seats {CAUTION: Rear Seat Operation The rear seatback can be tilted forward to let you reach the area behind it. If the seatback isn't locked, it could move forward in a sudden stop or crash. That could cause injury to the person sitting there. Always press rearward on the seatback to be sure it is locked. {CAUTION: To tilt the seatback forward, lift up on the lever located at the base of the seatback on the driver's or passenger's side and then push the seatback forward. To return the seatback to the upright position, push the seatback rearward until it latches. After returning the seatback to its upright position, try to pull the seatback forward to make sure it is locked. A safety belt that is improperly routed, not properly attached, or twisted won't provide the protection needed in a crash. The person wearing the belt could be seriously injured. After raising the rear seatback, always check to be sure that the safety belts are properly routed and attached, and are not twisted. 1-7