Chevrolet 2004 Monte Carlo Owner's Manual page 30

Lap-Shoulder Belt
All rear seating positions have lap-shoulder belts. Here's
how to wear one properly.
1. Pick up the latch plate and pull the belt across you.
Don't let it get twisted.
The shoulder belt may lock if you pull the belt
across you very quickly. If this happens, let the belt
go back slightly to unlock it. Then pull the belt
across you more slowly.
1-24
2. Push the latch plate into the buckle until it clicks.
Pull up on the latch plate to make sure it is secure.
When the shoulder belt is pulled out all the way, it will
lock. If it does, let it go back all the way and start
again. If the belt is not long enough, see Safety Belt
Extender on page 1-28. Make sure the release
button on the buckle is positioned so you would be
able to unbuckle the safety belt quickly if you ever
had to.
3. To make the lap part tight, pull down on the buckle
end of the belt as you pull up on the shoulder part.