Chevrolet 2003 Astro Owner's Manual page 37

If the belt stops before it reaches the buckle, tilt the
latch plate and keep pulling until you can buckle it.
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 1-34.
Make sure the release button on the buckle is
positioned so that you would be able to unbuckle
the safety belt quickly if you ever had to.
3. To make the lap part tight, pull down on the buckle
end of the belt as you pull up on the shoulder part.
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