Hummer 2003 H2 Owner's Manual page 20

Replacing the Third Row Single Seat
CAUTION:
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:
A seat that isn't locked into place properly can
move around in a collision or sudden stop. People
in the vehicle could be injured. Be sure to lock
the seat into place properly when installing it.
1-14
To replace the third row single seat, do the following:
1. Open the liftgate.
2. While holding the rear of the seat up, slide the front
wheels into the slots on the floor. The front latches
should lock into place. If latches do not lock, try
tilting the rear of the seat upwards.
3. Once the latches are engaged, let the seat drop into
place. Pull the lever labeled 1 and pull the seatback
up to return it to its upright position.
4. Push and pull on the seat to make sure it is locked
into place. The seatback cannot be raised to the
upright position unless the seat is secured to
the floor.