GMC 2002 Envoy - Manual (Page 19)

1-7
The rear seatback handles
are located on the outboard
side of the rear seatbacks.
Pull the seatback toward you as you lift up on the
handle. 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.