Pontiac Montana SV6 2007 Owner's Manual page 57

CAUTION:
{
Never do this.
Here a child is sitting in a seat that has a
lap-shoulder belt, but the shoulder part is
behind the child. If the child wears the belt
in this way, in a crash the child might slide
under the belt. The belt's force would then
be applied right on the child's abdomen.
That could cause serious or fatal injuries.
Wherever the child sits, the lap portion of the belt
should be worn low and snug on the hips, just
touching the child's thighs. This applies belt force
to the child's pelvic bones in a crash.
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