Hummer H2 2009 Owner's Manual page 17

Bucket Seats (Reclining Seatbacks)
Vehicles with bucket seats have a manual reclining
seat back function.
The lever used to operate them is located on the
outboard side of the seat(s).
To recline the seatback:
1. Lift the recline lever.
2. Move the seatback to the desired position, then
release the lever to lock the seatback in place.
3. Push and pull on the seatback to make sure it is
locked.
To return the seatback to an upright position:
1. Lift the lever fully without applying pressure to the
seatback and the seatback will return to the upright
position.
2. Push and pull on the seatback to make sure it is
locked.
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