GMC 2008 Savana Van Owner's Manual page 27

If you ever pull the shoulder portion of a passenger
belt out all the way, you may engage the child
restraint locking feature. If this happens, just let
the belt go back all the way and start again.
3. Push the latch plate into the buckle until it clicks.
Pull up on the latch plate to make sure it is secure.
If the belt is not long enough, see Safety Belt
Extender on page 1-28.
Make sure the release button on the buckle is
positioned so you would be able to unbuckle the
safety belt quickly if necessary.
4. If equipped with a shoulder belt height adjuster,
move it to the height that is right for you. Improper
shoulder belt height adjustment could reduce
the effectiveness of the safety belt in a crash.
See "Shoulder Belt Height Adjustment" later
in this section.
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.
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