Chevrolet 2005 Silverado 1500 Pickup Owner's Manual page 54

4. Pull the rest of the shoulder belt all the way out of
the retractor to set the lock.
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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.
6. Push and pull the restraint in different directions to
be sure it is secure.
To remove the child restraint, just unbuckle the vehicle's
safety belt and let it go back all the way. The safety
belt will move freely again and be ready to work for an
adult or larger child passenger.