GMC 2008 Yukon Denali Owner's Manual page 74

5. To tighten the belt, push down on the child restraint,
pull the shoulder portion of the belt to tighten the lap
portion of the belt, and feed the shoulder belt back
into the retractor. If you are using a forward-facing
child restraint, you may find it helpful to use your
knee to push down on the child restraint as you
tighten the belt.
1-70
6. If your child restraint has a top tether, follow the child
restraint manufacturer's instructions regarding the
use of the top tether. See Lower Anchors and
Tethers for Children (LATCH) on page 1-60 for more
information.
7. Push and pull the child restraint in different directions
to be sure it is secure.
To remove the child restraint, unbuckle the vehicle's
safety belt and let it go back all the way. If the top tether
is attached to a top tether anchor, disconnect it.