How do you know whether your seat belt is working?

On ALL my other cars, when you pull the seat belt really quickly, it will lock up. But on my Windstar, I could never lock up the seat belt no matter how quickly I pull.

So how do I know that my seatbelt is actually working? Dude, this is really serious safety thing.

On older cars, the activation mechanism was a weighted pendulum. On newer cars, the mechanism is electrically activated and timed to give you a little slack before stopping the unwind.

I supose I didn't really answer your question properly. If you want to test it, try slamming on brakes in a panic-style stop at about 30MPH. You'll see that the belts lock up.