Pontiac 2002 Aztek Owner's Manual page 45

The lap part of the belt should be worn low and snug on
the hips, just touching the thighs. In a crash, this applies
force to the strong 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.
The safety belt locks if there's a sudden stop or a crash,
or if you pull the belt very quickly out of the retractor.
CAUTION:
You can be seriously hurt if your shoulder belt is
too loose. In a crash, you would move forward
too much, which could increase injury. The
shoulder belt should fit against your body.
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