Buick 2004 Rendezvous Owner's Manual page 46

The lap part of the belt should be worn low and snug
3. To make the lap part tight, pull down on the buckle
on the hips, just touching the thighs. In a crash, this
end of the belt as you pull up on the shoulder part.
applies force to the pelvic bones. And you'd be less
likely to slide under the lap belt. If you slid under it,
the belt would apply force at your abdomen. This
could cause serious or even fatal injuries. The
shoulder belt should go over the shoulder and across
the chest. These parts of the body are best able to
take belt restraining forces.
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