GMC 2010 Canyon Crew Cab Owner's Manual page 40

To return the seatback(s) to the upright position:
1. Lift the seatback(s) and push it into place.
WARNING:
{
If either seatback is not locked, it could move
forward in a sudden stop or crash. That could
cause injury to the person sitting there. Always
push and pull on the seatbacks to be sure they
are locked.
2. Make sure the seatback(s) is locked by pushing
and pulling on it.
2-12
WARNING:
{
A safety belt that is improperly routed, not properly
attached, or twisted will not provide the protection
needed in a crash. The person wearing the belt
could be seriously injured. After raising the rear
seatback, always check to be sure that the safety
belts are properly routed and attached, and are
not twisted.
3. Reconnect the center safety belt latch plate to the
mini buckle. Make sure the safety belt is not twisted.
4. Push and pull on the latch plate to be sure it is
secure.
When the seatback is not in use, it should be kept in
the upright, locked position.