For 2 weeks now I have been trying to figure out why my truck will not charge. It started with simply not charging at all and I basically drove it until the battery ran down by roll starting the truck. I went to by a new alternator and they said it could be the crankshaft sensor if I had (and they gave me a list of problems). It sounded similar to the problems that I was having so I replaced the crankshaft sensor. And thanks to posts on this website I could find it and figure out how to set it.

After I replaced it I thought I had it licked, but when I would drive it would stop charging the battery. In idle it would charge. When I shift gears it will charge, but when I give it fuel it will not charge. Sitting still and increasing the RPM it still will not charge until it returns to idle.

I then read where someone put on an external regulator, so I tried that. It would only charge hotter in idle, but nothing at higher RPMs. I replaced the alternator nothing changed. I have readjusted the crankshaft sensor several times and it does not help.

Overall I am at a loss. Thanks for any help.

 

I ran into the exact same issue on a friends Chev truck. It would only charge at an idle. Turned out to be a faulty voltage regulator inside the alternator. I'm betting its the same issue with yours, although I don't know if its an internal or external voltage regulator.

 

That is why I even tried replacing the alternator and it did not help and hooking up an external regulator did not help. It just charged hotter when it charged. Does anyone know if the blue wire is supposed to have 12 volts when the switch is on?

 

Don't know what year your truck is, but if it's pre-computer, you might try changing the voltage regulator. Box on top of firewall in the middle of the truck.

 

If your truck's like mine ('93), over at the alternator side of the engine, down there at the charge-air plumbing going from the turbo to the IC, there's a bundle of cabling. There's a big cable in there that's coming from the alternator. It's got a plug and receptacle in-line.

- Make sure that connector is good-n-tight.

 

Need to fill out your truck info as different years had diffetent set ups for the voltage regulator. My first question is asking whether or not the nut on the alternator is tight. Sounds as if you are spinning the nut on the alternator when the enginge speed is ramped up

Second of to make sure youfollowed the sticky when intalling the external voltage regulator.

 

It is a 91 dodge. It has cruise and I am guessing it has the regulator in the computer. I have unhooked all cables and wires and hooked them back up. The nut is tight. It was doing the same thing on the old alternator.

I cut the green wire and ran it to the external regulator. That made the check engine light come on but it still ran fine and no wires got hot. I only tapped into the blue wire and ran it to the VR. I could not find a VR on the truck so I am thinking it may be in the computer if I have one.

 

Nope, 91 definitely has the external regulator...that little (probably chrome) box up on the firewall is known to go out all the time. As a matter of fact, I had to replace mine within weeks of buying my truck last year.

 

Some model year 92 trucks were likely sold near the end of 1991. Check you VIN for model clarification. Good ole Dodge and their model years!

When installing a regulator on a 92 style wiring harness:
Both plug leads come off the regulator and go directly to the alternator terminals. There should not be any other leads running from the old harness or anywhere else to the two connection points on the alternator. In other words this regulator operates independently from the old wiring harness. The power from the ignition switch is connected to the "I" lead. Of course the original BATtery lead is maintained full time by a fused connection directly to the battery. And you need a ground lead from the regulator to the alternator.


Regulator plug connector

 

also be sure the belt is not slipping.

 

I was thinking that same thing, actually.

 

The bad thing is I cannot find that it has an external regulator. I have looked all over the firewall and both fender wells and do not see anything that looks like a regulator. They say it is on the firewall towards the middle but I do not see one. I really do appreciate all of the help.

 

On my 91.5 it's the silver box above the valve covers and to the pass side a bit:


Actually...it's at the same spot on this 89:

 

Mine did something similar....bad voltage regulator...

 

I don't have anything up there. I have learned that eventhough mine says 91 in the door it is considered a 92.