So I put a tuff stuff Chrome alternator in my truck. But when I was putting it in the insulator boot was not on properly and I accidentally grounded it and burnt a fuse link. Didn't appear to be any other issues that I could see. I replaced the fuse link. With a fuse link btw. Put the alternator in. Truck started but the volt gauge was bouncing all over. Tested at the battery and the voltage was jumping from 14.5 to 15.5ish. Thought maybe it was the voltage regulator. Replaced that. Same thing. Maybe something happened to the alternator. Took it out and put the old one back in which was working fine. Same thing. Anybody have any suggestions. Pulling my hair out here.

 

Well, the only part that it now points to is the new alternator..... couldda blown a diode in its rectifier. Oooops. Have it tested.

If it were a 3G,.. oh never mind. It's not.

 

But the old alternator which was working perfectly before is doing the same thing. Wouldn't have happened to the alternator that was sitting in the bed. Starting to think I should be cutting the tape and tracing all of the wires between the solenoid the regulator and the alternator.

 

OK... It's not clear to me by what was originally described that the old alternator was reinstalled at some point.

 

Yup. It was. It turns out that when I was replacing the fuse link I eliminated a factory 4 wire splice. Since the fuse link was burned clean down into what I though was an insulator I just eliminated it am carried on. Turns out that insulator was a four wire splice from the factory. When I replaced the link I ably did the 12 gauge to 16 gauge fuse link. The other two wires should have been in the same splice. All good now.