GMC 2005 Envoy Owner's Manual page 57

5. Pull the rest of the shoulder belt all the way out of 6. To tighten the belt, push down on the child
the retractor to set the lock. 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. You should
not be able to pull more of the belt from the retractor
once the lock has been set.
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