Need Help!! Electrical issue???

[Mopar1973Man]

There should be a green and blue wire going to the field wire of the alternator. The blue wire should be hot 12V when the engine is running and the green wire should be a variable ground. Now the PCM is the voltage regulator so if the alternator is still not working right you might end up doing a old school regulator or changing out the PCM. http://mopar.mopar1973man.com/cummins/general/voltage-reg/voltage-reg.htm

[99dgcummins]

Is there a way to test the PCM? I dont want to buy a new one if there isnt anything wrong with it. I know all signs point to it but after rent, bills, and diesel(my commute is about 140 Miles/day) so I dont have much at the end of the month.

[Mopar1973Man]

The only way to be sure is get a hold of a dealer and have them drop there DRBIII tool on there and run a diagnostic on it. That will hurt for at least a shop hour at the dealer... (~$100)

[99dgcummins]

ok maybe ill try that first. Thank you!!

[99dgcummins]

So months later I am still having the problem. I finally decided to just take it to the Dealer. I've never taken a vehicle to the dealer so I am not sure if this is a normal thing but they wouldn't give me any codes, let me talk to the mechanic who ran the tests or anything. I had to deal with a middle man and all he would tell me is that I have a bad ECU. Does that sound right? I have tried to pull codes with a scanner and i got nothing so I am wondering if they are just saying it is the ECU because they couldn't get anything off of it. Them not letting me talk to the guy who ran the test made me suspicious. Should I be suspicious?

[Mopar1973Man]

Voltage drop test? http://articles.mopar1973man.com/general-cummins/34-engine-system/136-voltage-drop-testing-of-wiring-and-feed-cables

[2500ctd]

Hang on a second... Before chopping up any wiring just remember these truck ran 9-10 years without wiring mods and did just fine. So now all of a sudden require a bunch of hacking and cutting, adding grounds, etc... I don't thinks so. I still say to look for the issue at hand and not cover it up with a bunch of band-aids like adding grounds, filters, and tin foil...

Yes and no. 10yrs is a long time. Corrision can seep in, strain on the wires, and maybe even a bad connection from the get go. I agree the tin foil is little excessive. The black helicopters can see through the foil......

Just bench test your current alternator before buying a new one... Save some money if you can!

Do you have a diy way for this? I would like to try it. I dont have a way to load the alt down though.

Mike, a guy on TDR, Gary from Canyon City, Oregon found those two connectors have some issues with resistance. Maybe some don't but could be a step in the right direction for stopping future problems. The fact that the OP had to keep opening and closing one of them shows something was wrong there possibly. Do not want to give anyone a bum steer...

As for the connectors just measure either side of them. Any voltage drop equals resistance. Then I would clean the connectors. Actually cutting and splicing or actually replacing with a single wire is best. All connections introduce an area where issues can start. All the seemingly over use of connectors in our harness is only to aid in assembly. I am redoing some wiring under the dash on my truck now, and C134 is the new version of the oldschool bulkhead connector. They are good connectors as stated they can last a long time and often do. Until someone gets in there and hacks it up. Which I am fixing. Simple testing can determine if a connector is really bad or not. I wouldnt go eliminating all the connections on a whim. Now If I was rewiring from scratch I probably would then. On the driver side dash support is a main ground for alot of wires. Like 8 wires going to one ring connector. I looked at it and it seems like a pressure weld type of connection. Very secure looking. Now the fact that the dash support is not painted and has surface rust, well I am going to disconnect the ground clean the area back to bare metal and then hit it with some dielectric grease. Figure inside the truck protected from the elements it should last a long time. Plus I am going to add a nut on the stud to piggy back off the factory ground. I am also adding a seperate fuse panel. I have done enough bad wiring to know what doesnt work in a couple years.

[JAG1]

I know about testing for voltage drop on either side of the connectors to see if they are good... always a good idea. Then I think about road vibration and elements. I know wiring can look good, test good, and then you can accidentily move a different way and find it's bad.My trans started the hunting issue so I eliminated those two connectors off the pass. battery. On the same warm day, I noticed how there is a wire harness underneath the alternator mount bracket, but, this wiring was laying on the alt. itself, so I zip tied that up off the alt. and my hunting issue has not come back since.Hey Mike about me eliminating those connectors.... there!