Hi, newby here and novice to boot. Please bear with me (THANKS)! My vehicle: 1998 Ram 1500 van with 2000 engine, 5.9. Bypass hose tore a "new one" a few days ago (a huge hole it was). Got it replaced. All dry now. Went to get the van inspected. On the way home "check gauges" light comes on. Voltage gauge between 0 and where it should be (14.6). Off to AZ. Battery test ok, needs charge. Alt not so much-not charging battery. Got a "new" alt from "Yard", bench test good. Charged battery, threw "new"alt in, same difference. Made sure everything's good and tighty. Tensioner assembly and belt less than 2 years old. Been doing a lot of reading, but having troubles with electrical testing, as the electrical hook ups are on the backside of the alt. Hard to get to and can't see a thing. Checked wires visually as best I could. The harness disappears behind the compressor for a stretch, then back out towards the battery side. Never had any issues of this nature before. Everything else is working. Could all the water (with coolant of course) squirting all over the engine compartment under the hood have taken out something? Any guidance will be MUCH appreciated!!!

 

If the alternator bench tests good, but, won't charge when installed, that's possibly a failed voltage regulator.... which is part of the PCM.

 

Thanks for your input HeyYou. I have read Maaaany posts about this issue here and elsewhere, and of course the PCM//voltage regulator always came up as a possibility. But nowhere did I ever read anything about the 400A alternator fuse. I stumbled upon this when I was researching how to troubleshoot electrical components, and taking a closer look at my fuse box, wondering what this bear of a fuse might be for. Some more research and my manual finally told my "hey, it's your alternator fuse". Checking for continuity did the trick. My mega fuse for the alternator was blown, and replacing it did fix my issue. Mind you I had nothing else not working, so I hope that the dowsing from my busted bypass hose shorted something, maybe even the alternator, and is no longer an issue now that everything is dry.

 

Just want to throw this out there...
I had the bypass hose leak and when it did the coolant seeped on to the belt.
When this happened, the belt would slip with no sounds of squeal and additionally, the power steering worked.
Only the alternator was slipping and the volt meter indicated 0v.
I have had a heck of a time with the tensioner and pulleys too. If these aren't regularly changed, I would have a similar issue too.