My alternator quit charging about a month ago. A friend who runs a small fleet of Dodge trucks at the port told me how to wire an external regulator by splicing into the original harness, only slightly different than the way others have shown how to do it on this site. It worked fine for about a month.
A few days ago it quit working again. I had another regulator so I put it on, it worked one day and quit. I didn't have time to work on it so I ran it for two days on just the battery.
Today I unhooked the regulator and tested the alternator and it was putting out just fine. I decided to wire the regulator the way it has been shown on this site. I was having a hard time finding switched 12 volts so I just temporarily ran a wire from the battery to one of the small alternator terminals. It still wouldn't charge. I decided I needed to get new brushes for it and went to hook up the battery charger so I could run the truck tommorow. When I went to hook up the charger I saw my meter was reading 17 volts!
I am assuming I need new brushes, maybe that's why the alternator seems to be intermittently charging, the regulator is fine. If so, I am still confused about how to wire in the regulator. Could I have applied battery voltage to the wrong terminal? It won't charge at all on one terminal and overcharges on the other terminal.
And I know it sounds stupid, but where can I find switched 12 volts? I could only find a couple of ten gauge wires, none of which had power. I hate to keep probing and possibly causing new problems. I would really appreciate any help i can get. This is my work truck and I can't afford to have it sitting in a shop for any length of time. Gotta keep it working!

 

Hey look at my post

GEN light again.. it should answer ur questions thanks im havin the same issues

Tx

 

for one thing you must remove the original wires from the alternator except for the large main output wire, rather than "splice into them." If they are still connected, that is the problem. You do need to run a ground wire to the regulator base from the alternator frame. On the power feed for the regulator I do not have a book on your model so do not even know if you have an ASD relay to pull it from. Worst case is to pickup a wire from the ign switch and run it through a relay to get power for the regulator. You should not have to do that though. If you are charging 17 volts the regulator is shorted or has a wiring problem. It should only charge from 13.7 to 14.5 or somewhere in that area.

 

I have disconnected the original wires from the alternator. From rereading these posts and an earlier one from mt72916 (thanks) it looks like I can splice to the original blue wire to get switched voltage. Long day tommorrow, when I get done I will try it again. Batteries are fully charged now, should get me through the day.

This truck has had a hard life, 300,000 miles of towing a fully loaded fifth wheel trailer all over the country. Lots of little annoying problems, all electrical. Mechanically, I think you could put a grenade under the hood and not hurt a thing. It still runs hard every day, earning me a living, and I wouldn't trade it for anything.

I will try to get the wiring correct tomorrow, thanks for the help.