[RogerRamJet]

Did you check the cable from the alternator to the battery? If the alternator is producing a charge, then you should be reading 14+ volts at the battery when the truck is running. If not, then you have a bad alternator or a bad cable. How old is your battery? A bad battery could cause your alternator to malfunction.

 

[vdubs63]

Today I went and exchanged my alternator for another one and I also bought a new battery because my old one was shot. My battery reads 12.40 just sitting there and it reads 11.90 while running. I went to take it around the block right after I put in the new stuff and the Check Gauge light came back on and the Charge Gauge went to the red line. I checked my cables and fuses and they are all ok. I'm have run out of ideas of what could potentially be wrong.

 

[RogerRamJet]

If it's reading 11.90 while running, you either don't have the alternator hooked up correctly, a bad wire or the wrong alternator. While running, you should be over 14. Check the voltage coming out of the alternator.

 

[Lazarus Truck]

X2! With Roger. 12v DC is fickle. Terminals MUST be clean. It takes very little to stop 12 volts. As Roger said, check the voltage coming OUT of the alternator. Check it first to a CLEAN engine ground, then an chassis ground, then to the battery negative. Check it at the battery cable end, and check it at the battery post. Should be the same.

 

[vdubs63]

Ok, sorry I took so long to respond I've been busy with work. So I figured out what is wrong at least. The voltage regulator in the PCM went bad, therefore it is not properly regulating voltage for the alternator, and that is why they tested good at the parts store but ran at a lower voltage in my truck. I found that a new PCM is $230 plus shipping plus I have to get it flashed at the dealer. I might go try and find a used one at the dodge dismantler. However in the meantime I had seen in another forum about the external voltage regulator mod and it seemed very do-able so I bought the parts (about $65) and wired it all up and it worked just fine for the first week and now my battery pings that its overcharging and my check guages light comes on.... It's like it's never ending.

Heres the link for the mod:
(original article)
http://articles.mopar1973man.com/general-cummins/34-engine-system/134-voltage-regulator-mod

 

[RogerRamJet]

Normally I would say Voonderbar! But, since it only seemed to add another issue, I'll just say thanks for the update.

 

[Lazarus Truck]

Try Auto Module Source. https://www.automodulesource.com/ My module failed, and got mine for about $180. It was pre-loaded with all up-dates. I have had no issues with it for 9 months.