Chevrolet TrailBlazer Owner's Manual page 14

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.
1-8
Rear Seats (TrailBlazer EXT)
The second row seat is a 65/35 split seat which may be
folded and tumbled. Use this feature for gaining
access to the third row seats.
To fold and tumble the second row seat(s), do
the following:
1. Push the head restraints fully down.
2. Fold the seatback flat on the seat by pulling up on
the front part of the fold and tumble lever. The lever
is located on the outboard side of the seat and is
indicated as 1 on the handle and side of seatback.
3. Release the rear set of seat hooks from the floor
pins by pulling up on the rear part of the lever
indicated as 2 on the handle and side of seatback.
This enables the seat to be tumbled forward.