I have a 2001 Ram 2500 with a 24v 5.7l diesel. I have started having some weird problems and I have no codes to determine what exactly is going on. Everything started yesterday for me. I noticed when I left work that the voltage gauge was in the 12v range which is normally about where it sits but then as I drove I noticed the gauge was not moving at all. When I got home I checked things out and found that the batteries were sitting at about 12.34v with the truck off with it idling it sat at about 13.3v then when I revved it it got up to 13.8 which is not normal as at 2k I am normally about 14.5 volts. When I went to start it up today it idled about where it was at the day prior then as I started to leave the voltage gauge dropped all the way to the bottom and check gauges popped on. I shut the truck off restarted it and the gauge went back to the 12 ish volts and would fluctuate on my driving. When I got to walmart it did the same thing again voltage gauge at 0 and upon restart it went away. I tried to recreate the problem and could not next time it does it I will check if it is actually charging. How should I troubleshoot this problem. I'm thinking it could be a ground problem or even a PCM going bad but I have no clue on how to even check the PCM... Should I take the alternator out and have it tested? The batteries are new from last year and show no signs of damage as well. What are some of your guys thoughts?That is the only gauge I am currently having problems with as well. I have no other problems with any other gauges...

 

Have thr alternator tested. Mine was doing the same thing. It was the alternator