GMC Sonoma 2001 Owner's Manual page 19

Seatback Latches (Regular or Extended
Cab Only)
To fold the front seatback forward, push the lever on the
side of the seat rearward and pull the seatback forward.
To return the seatback to the upright position, push the
seatback all the way back until the latch catches. If the
seatback was reclined before being folded forward, it
will return to the reclined position.
The front seatback folds
forward to let people get
into the rear seat or to
access the storage area
behind the 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.
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