Once you know you have a good one, make SURE it is actually connected when installed. Corroded connections in the three wire plug or a missing output wire (or misplaced) so you never connect to the positive battery post will result in a "dead" alternator because it has not field current.

Hi ho, back up the train here Charlie. My alternator (77 240d) has a 3 wire plug thingy that goes into the alternator. And that's it! I always assumed the main alternator output wire was one of those three in the connector. Am I missing something important here. The alternator has the regulator that screws to the back, and it has a large capacitor across the back, but it has NO BIG OUTPUT WIRE like every other alternator in existance. Please clarify. Thanks, this could be the ticket.

Kip Amore