alternator not charging.

[Oggward]

Hello, my father got gifted a 2003 C5 some time ago, it was some issue with the original engine that made it leak oil into the combustion chamber. So we have changed that, and we have almost got it road legal, the only issue is that the generator has stopped charging. It worked according to my dad when he got the car, but now it has stopped charging. I have made sure that the B-pos cable is connected to the battery and both signal cables are getting current through them. I am wondering what else kind of problem could have made it so it stopps chargeing. I have not found a diagram of the original alternator, so i dont know where it is grounded. Thanks in advance from sweden.