GMC 2001 Sonoma Owner's Manual page 31

Q:
What's wrong with this?
A:
The belt is twisted across the body.
1-18
CAUTION:
You can be seriously injured by a twisted belt. In
a crash, you wouldn't have the full width of the
belt to spread impact forces. If a belt is twisted,
make it straight so it can work properly, or ask
your dealer to fix it.