On my way to work today my check gauges light came on and I saw my voltmeter pegged to the right, my truck is a 2000 Ram 2500 V10. I was almost to work so I pulled into the parking lot and shut it down. Before I shut it off the radio had shut off so I'm thinking its not a screwy gauge but an actual charging issue. Started it back up and everything was normal. After work on the drive home everything was OK as well. Do you think the alternator might be on the way out, or should I be looking at something else?

My 2000 CTD 3500 has done that before. The positive feed to the fuse panel under the hood had loosened up. It had done it a couple of times until I put a star washer under the nut to keep it from backing off.

Just checked and all the wires are tight on the alternator and fuse block, nothing visibly wrong either. At least the alternator looks easy to get to if I end up changing it out.

Test the voltage regulator

Did some more looking around online and this seems to be a fairly common problem, and it looks like many people have wired in an external voltage regulator to bypass the one in the pcm. I'm going to double check the grounds tomorrow since I only checked the wires to the fuse block, alternator and battery. Has anyone here done the external regulator bypass? If it turns out to be the regulator this looks like it will be a lot cheaper than a new pcm. I'm hoping it is just a loose ground since so far it has only happened once and not every time I drive it.

I have a 92 caravan doing the same thing, high charge, new alternator . Every time I scan it with a drb it gives a target voltage and it is exactly where it should be, like 14.5 on a 60 degree day. I have tried other batteries, cleaned underhood grounds, the gauge reads just below 18 volts, it is not boiling water out of batteries and drove it like this for 2 years. It must be the pcm but why does the DRB scan tool say it is perfect?

the external swap is quite common.
just get a 70 and up vr from the parts store for 15 bucks and find a 12 volt key on source.

the wiring diagram to convert a single field vr to dual is in the tech archives. Just wire up your alt the same, and it will work fine.