Alternator Replacement: I F'ed something up....

I recently discovered the alternator on my '91 XJ went out. So, I figured I would go ahead and replace it. Easy enough, right.....

Got the old alternator out and the replacement from Autozone in. Started the Jeep up, and noticed I was still charging just under 12V per the dash gauge (verified with a voltemeter at the battery also). So I shut it down and went about checking connections. Turn out I had missed the single black wire. Since I was rushing I didn't think to disconnect the battery ground before attempting to connect that black wire. Made contact with something while trying to get the wire back on it's pin and that tell-tale a loud snap. UH OH...

Disconnected the battery ground, connected the wire and reconnected the battery. This time when I went to hit the key, all it would do is crank. No start.....

I then checked the codes and pulled a 41: Alternator Field Switch

What does that mean? What did I do to my poor XJ? I'm assuming the new alternator is toasted at the very least. Please help.....

Thanks.

no too sure but i have heard that some xj have the regulator in the ecm . could be a bit more than just swaping out the alt. good luck wish i was more help

True that the voltage is regulated by the ECU on your '91, but I don't think that should be your problem. I'd take a look at the 2 big fuses marked alternator in the relay box under the hood. I've popped one of them before on my '91, but I think it still ran just didn't charge. Worth checking anyway if you haven't.

Yes, voltage is regulated by the PCM. There was even a sticker on the new alternator mentioning the external regulation. I did find and check the two 60 Amp alternator fuses and they look fine. Didn't look at any of the other fuses though.... It was getting too cold out.

Will check again tonight or tomorrow. Thanks.