Alright, so I put a new ignition cylinder in my car, and now it won't start. I noticed that the little black plastic thing that you screw onto the cylinder is a little busted up.

All the lights on the dash come on with the key in I/II, but when I turn it all the way, everything just shuts off.

The piece was a little busted before, but it still worked fine. I'm wondering if I busted it all the way this time.

Would this keep the car from starting? What exactly is this piece called, and what's it for?

if you could give me some insight into what piece you are talking about, i may be able to help you. I am kinda confused on the desciption that you gave me...let me know and i will get back to ya.