Chevrolet 2005 Colorado Owner's Manual page 34

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 would 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 is a sudden stop or a crash.
The safety belt also locks if you pull the belt very
quickly out of the retractor.
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CAUTION:
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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.
To unlatch the belt, just push the button on the buckle.