I have a 94 4.0 YJ. It seems to be having a strange charging system problem. It will sometimes be charging above 14v and sometimes below 14v. It was dropping down pretty much all the time when the rpm's were high, so we thought that the brushes were going out as that is usually a common sign of it. I had a rebuilder build me an alternator figuring i would change it before it strands me.
After changing the alternator, I have noticed that it is still kinda doing the same things as before. Ive also noticed that every time it is put in reverse (manual trans 5sp) the volts drop maybe to around 12v. I know these are grounded through the PCM. I dont think the charging voltage has dropped below 12v and I have never had a dead battery or no start as a result of the charging system.
Anybody had similar problems? I have cleaned all the battery terminals and the battery is new and in good condition. Im almost wondering if the original alternator was even bad at this point.
Any help is appreciated.