electrical haywire all of a sudden when reattaching the voltage regulator

[nvrbdn]

Car was running fine. Everything working, but was not charging the battery. I had an extra alternator, so I was going to change it and see what happens, but then noticed that the plug on the voltage regulator was loose. I plugged it back in and was back to charging the battery again.  BUT............  now the amp gauge is running negative, and as I rev the rpm's it goes farther in the negative to 30 amps. The tach quit working. If I disconnect the positive cable, with the engine running, when I reattach it I get a big spark. Engine still running great, just some weird electrical stuff going on.

[charger Downunder]

Sounds like you have a major short somewhere check the connection to the alt the fiber washer hasn't fallen apart on the positive cable to alt.

[nvrbdn]

Thanks for the info!!! I will check that out.

[John_Kunkel]

How do you know the battery is charging if the ammeter is showing discharge?

[nvrbdn]

Right, I don't know, but with the battery disconnected, the engine keeps running. With the regulator disconnected the engine shuts off. I haven't put a meter on it yet. I put both alternators on the engine, and the results were the same with both.