So I have a 06 magnum with a aftermarket alternator for my stereo,I've also upgraded the battery and have a voltage meter built into the vehicle.now some months later I'm running into a problem when I start the vehicle it won't charge,initially if I started it and let it run for a few minutes at 11.6 i would hear the alternator kick on and 14.3 no issues,then it stopped doing it on its own and I accidentally figured out I could wiggle the alternator harness to make it charge and most of the time a simple wiggle would keep it running.so I had the alternator tested and it ran just rine leading me to believe maybe it was the harness,so I chopped and soldered a new harness in and that also didn't fix the problem,also now if I wiggle the harness to get the alternator going if I drive the voltage will spike up and down occasionally,usually 11.9-14.8 up and down and then it goes back to normal. The only other thing I could think is it would be the voltage regulator and my aftermarket alt doesn't have one,from what I understand it's built into the ecm,but why does wiggling the harness have any effect then? If anyone has any ideas please let me know cause I've been scratching my head on this one for a while

 

I would try a different alternator....... seems like something isn't quite right there.