I have a 91 d250. For the last ten years it’s had a pop up over charging problem that would only pop up every once in a while. Well about 2 months ago she went mad overcharging coming home from work. I put on a new regulator. Thought that helped for a few days. Started over charging and not charging. Then stopped. I didn’t know that the new regulators were crap. The alternator did out so I stopped at Napa and bought one. Still no charge.
I’ve been putting my charger on overnight but sometimes it isn’t feasible and in emergencies I will ground to my fender and full Field her.
it charges at 14 volts at idle but over idle it’s 15 to 18 vdc. Well I got busy yesterday and forgot to take the ground wire off and smoked the alternator. I was wondering if there was a one wire alternator on the market to bypass all this charging crap.

 

I googled one wire alternator 1990 dodge w250 diesel and there were quite a few showing. As for what is going on with your truck you are right the voltage regulators you get at the local parts stores are junk if at all possible get a genuine Mopar.Another thing you can do is run a new signal wire using a relay with voltage direct from the battery.

 

PA performance makes a one wire alt for our trucks. I had an alternator shop rebuild my original and put a one one hook up in it along with a w wire for a tach hook up. They charged me $80.

 

Thank you so much guys I had Google before but my results were coming up with other alternators.