Chevrolet 2009 Uplander Owner's Manual page 42

5. To make the lap part tight, pull up on the
shoulder belt.
It may be necessary to pull stitching on the safety
belt through the latch plate to fully tighten the
lap belt on smaller occupants.
1-38
To unlatch the belt, push the button on the buckle.
The belt should return to its stowed position.
Before a door is closed, be sure the safety belt is out of
the way. If a door is slammed against a safety belt,
damage can occur to both the safety belt and the vehicle.