I have a 1997 ram 2500 diesel. It started having voltage issues where it would bounce from 14-16 volts down to 8-10 and then back up again, it would do it repeatedly for awhile but only in gear, would not do it in neutral. I figured it must be an alternator issue so I went and bought a new alternator, didn't solve the problem. Then we checked the wires off of the batteries, alternator, grounds, everything is tight and clean. We then installed an external voltage regulator thinking this would solve the problem. it did solve 90% of the voltage irregularities, but it would still randomly bounce up and down, but not for very long and always stopped. Worked for about a month and then yesterday the truck was running fine, no voltage issues at all in the last week, shut the truck off for lunch, started it back up a few minutes later and my gen light came on and voltage wont rise above 12, usually sits between 10-12 causing the gen light to come on. Any suggestions to something I could be missing? Im about on my last nerve trying to figure this out

 

Isn't the voltage regulator in the PCM? Just wondering how you could rig up an external regulator? Then again I may not know what I'm talking about.

 

Actually, ReadRam is correct. Apparently though, there IS a way to install the external regulator (not using the one in the PCM,) yet still not annoying the PCM enough to set codes. Check the other charging thread for a link. (posted today, should still be on the front page.)

 

yes you can bypass the ecm by installing an external regulator. I just went and bought a new regulator today thinking maybe the old one took a dump, my power comes from my gauge fuse, so everytime the key is turned on it has power, I have power at the fuse, both batteries when running are at 12 volts. After I switched the new regulator, it wont even hold charge, when the truck is running it holds it at 12 volts, but as soon as the truck is shut off and you try to restart it, it is completely dead....im out of ideas, im going to have the alternator checked again, I previously had it checked by 3 different places and all said it was good. I wish it would just start on fire and burn in hell at this point haha