So I just picked up a 2002 2500 Cummins with 247k on the clock, runs great all is in in good and apparent shape, and now when I want to get it inspected I have 5 DTC's..
1. - p 0622 - generator field control circuit

2. - p 1492 - Ambient/battery temperature sensor volts too high

3. - p 1765 - transmission 12 volt supply relay control circuit

4. - p 1594 - charging system voltage too high

5. - p 1693 - but this is only on because there is more than one code present

Alrigh so first off, I'll start the truck, voltage gauge will start to read the normal charging voltage and all is good, but from time to time, it will peg to the right side reading 18+ charging volts. Now the alternator was replaced a few months ago and the previous owner did it himself, but I don't think he knew what he was doing. Further looking into it I see some wires spliced, cut, and jury rigged in there, leading me just to shake my head.

The truck seems to surge about 50 rpm if that bouncing at idle, on and off also, like 30 second intervals if that helps anyone. Now the tranny shifts late 1-2 and 2-3, locks up great in o/d and 3. I'm not sure if that has to do with the electrical issues or that is just the fluid level being high that I just found out about.




The first picture displays the wires coming off the back of the alternator, one green and one black ( as seen in the picture) Not too sure what these are meant to go to.

The second picture should be a picture of a regulator, not really sure if that's supposed to be there or not, but its in there.

The bottom part of the third picture are what looks like a single black wire and is actually a black and green which come from the alternator, as seen in the last picture, again, not sure what the purpose but go to the regulator.

If anyone can help with this issue and help me get rid of those codes that would be great. Thanks in advance!

 

What does each of the wires connect?

 

The battery temp sensor will need to be replaced. That will fix that. I would look for an alternator circuit drawing. That way you can sort out the birds nest of a wiring job you got there. Once you get that sorted the rest of them should go away.

So does the wiring run from the alternator to that box? That box is not factory. Where do the wires run from the box to?

 

They're spliced into other wires in there, and one goes to a red wire which runs back towards the driver side of the truck. Its only about 2 different wires.

Do you know if anyone has like a wiring diagram? or if anyone has an indicator of each wire that goes into the computer on the passenger side by color code? Thank you

 

**Notice**

Just had a friend come look at the truck and we started up the truck, turned on the headlights and if you look at them you can see them ever so slightly like dim in and dim out and the dash lights do the same thing if that helps anyone.


I also talked to the old owner and he said he put in that voltage regulator because it used to overcharge the truck really bad, and he put new batteries in the truck and alternator to try and fix this problem.

 

I recently read about this exact same problem. If I recall it was on Mopar Man .com in the 2nd gen. section. It tells the cause and the repair complete with directions for the repair.

 

do you mean mopar 1973 man.com?

 

That's what he was talking about

 

Do you recall the name of the thread a little bit more by chance?

 

I think I found it, for anyone else that wants to see it.


https://mopar1973man.com/cummins/art...ator-mod-r342/