My truck came with an externally regulated alt. The previous owner swapped in and internally regulated alt and hooked up the red wire from the connector. And I swapped higher amp ( his 25 amp mine 55 amp Toyota reman) alt made for the 22r. It had two connectors I hooked them up and everything worked fine most of the time. I taped the second to the yellow wire and it sender voltage and runs great.

But sometimes,getting more common, the truck will not charge till u rev it to about 3k then from the pass side can hear a relay ping and the volt meter jumps to 14 and it is charging. And clue why it is doing that? And what exactly is over there to make that noise ?