Buick 2006 Rainier - Manual (Page 49)

4. Pull the rest of the shoulder belt all the way out
of the retractor to set the lock.
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.
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