I have a 2001 Ram 2500 4x4 with the 5.9L and 244,000 miles. Wednesday while driving, the red Check Gauges light comes on, and the batter voltage gauge is dropping and dropping. Luckily, I make it home. After popping the hood and re-charging the battery for a few hours, I start the truck up. The voltage gauge reads 14V. I think... "all is well".

The next morning while driving to work, the battery voltage gauge starts out at 14V right at the start, but after 10 mins of driving drops back down and the red Check Gauges light comes on again. Same thing exact thing when driving back home. This time when I get it home, I take out the battery and the alternator and take them up to Autozone. They test both, and told me that the alternator is bad, and I bought a replacement one. I get the new alternator home, put it and the battery back in, and start the truck. Battery gauge looks good at 14V and I think life is good.

This morning, the exact same problem happens again when starting up and driving to work...this time with the new alternator. I call up the manager at Autozone, who used to have a 2000 Dodge Ram 1500. He said that it sounds like the electronic voltage regulator (EVR) that's located within the PCM is getting hot and/or is going bad.

Does this make sense? I'm not sure if this will be a junkyard part or not. Suggestions? He suggested that I may want to take off the PCM connections and make sure they're clean.

 

Yeah, voltage regulator is in the PCM. If it's failed, time to replace the PCM. Being as yours is an 01, it needs to know the correct vin number, otherwise, it gets annoyed..... You might be able to find a replacement in the junkyard, but, you will have to have it flashed to your vin. That's gonna be the dealer, or, if there is a GOOD independent shop in the area, see if they can do it.

 

Aye - thanks. I thought about 2 other questions:

1. I did a search for websites and a PCM for my Ram. Found a couple that sell remanufactured PCMs that offer a warranty and will flash to your specific VIN number. Thoughts?

2. I don't quite like the fact that the plug in wire connector (with the 2 wires, green and blue) just didn't "snap" in there. There seems to be quite a bit of squishy resistance to make it go in there. Any chance it could be the source of the problem? As in maybe bouncing loose after a few miles? I'm just guessing.

 

Did it feel the same on the original alternator? How does it look to you?
Looks to me like it should snap in.

 

I would be more inclined to see if you can get a PCM locally....... Some of the aftermarket companies have absolutely horrible reputations.

 

If you can confirm that the regulator in the PCM is failed, the cheap/easy fix is to install a late 70's Chrysler electronic regulator. There are howto's sprinkled around the web. BUT first confirm that the PCM regulator is shot because it's even cheaper and easier to fix a broken wire.

 

Well, even though the plug doesnt snap right into place, I can push it all the way in. There's a local shop that's really good with up to date higher end diagnostic equipment. I have my truck in there right now so they can scan the system and tell if it's the PCM volt reg.

If it is the volt reg...I like the websites/projects for wiring up an external voltage reg from the late 70s. Just like most of the pages say, my truck runs great except for that darn volt regulator.

 

It's unlikely but you may want to check the alternator fuse in the distribution center. If you look in the service manual there is a section on diagnosing both the alternator and regulator/pcm. Higher end equipment is useless if it's not the right equipment to test it. It's more involved than plugging in a scanner. I'd make sure it's bad before spending $$$ on a pcm.

 

Ding Ding! Moparite gets it! The shop did a complete scan of the charging system including the PCM, with the computer showing the fuse being the issue. The tech looked inside the power distribution and found that the jacklegs that I bought the truck from must have blown that 140A fuse before and just hooked up a jumper wire around the 2 terminals. The wire was starting to melt into the plastic and fail (GASP). Luckily the truck didn't catch on fire! Case closed...for now I guess.