GMC Sonoma 2001 Owner's Manual page 49

3. To make the lap part tight, pull down on the buckle The lap part of the belt should be worn low and snug on
end of the belt as you pull up on the shoulder part. 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.
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