I have the battery disconnected (pos and neg), and nothing is connected to my alternator. When I connect a multimeter's common (black) to the positive pin and the red to the alternator housing, I get a reading of around 500. If I test it the other way around, I get a reading of 0. I read this is correct and indicates the diodes in the alternator are working correctly.
But as soon as I attach the alternator's positive pin to its cable (the battery is still completely unconnected) and repeat the same tests, I get positive readings both ways, indicating that the diodes are bad.
I am sure this tells me something, but what does it mean? Why does that happen? (Because of this, I replaced the alternator, but the "new/used" one does the same thing.) I'm sure it is something down the line, but I want some help finding the problem. (The battery is draining, and electrical problems)
