Chevrolet 2004 Impala Owner's Manual page 14

To raise the rear seatback, follow these steps:
1. Raise the seatback up and make sure it latches.
Push and pull on the seatback to be sure it is
locked in position.
CAUTION:
{
A safety belt that is improperly routed, not
properly attached, or twisted won't provide the
protection needed in a crash. The person
wearing the belt could be seriously injured.
1-8
2. Reconnect the center
safety belt latch plate
to the buckle.
CAUTION: (Continued)
CAUTION: (Continued)
After raising the rear seatback, always check
to be sure that the safety belts are properly
routed and attached, and are not twisted.
Make sure the safety belt label is pointing to the release
button, and that both are facing the front of the
vehicle. Make sure the belt is not twisted. Push and pull
on the latch plate to be sure it is secure.
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.
When the seat is not in use, it should be kept in the
upright locked position.