Heres the skinny. Friday night, truck wouldnt start, jumped it, it died a few miles later and woukdnt start. Ok, bad alternator. Replaced it in the am, jumped it, fired right up and ran fine. But then it started to drop in voltage and bog down and eventually died. Jumped it, ran fine, realized one plug was very loose. Someone called it a signal wire.
its one wire coming off a 3 wire plug, and plugs right into the alternator. Seems it would be a ground.

Now, it stays running, and doesnt die, but my voltage runs low, i estimate around 9-10. Windows and wipers are slow, thats expected. Today in a drivethrough my voltage dropped to 0 as well as rpm but the truck was still running and driving. Messed around with that plug, and voltage went to normal as well as rpm. But occasionally drops again. shut the truck down at home, it wouldnt start. Had to jump again.

So my question, is am I right thinking that plug is a ground (yellow wire black stripe) and this is a grounding issue. And if thats that case can i just snip that wire and ground it elsewhere? Or does it in fact act as a signal wire as well, and if i relocated it, it wouldnt show rpm or voltage?