I have asked around on this before but I am at a total loss as of now. 2001 Dodge Ram 2500, Auto, Cummins, bone stock.
From time to time my check guages light will come on and the volt meter will peg out at 18volts, it may stay this way for a minute or 20 minutes. I have ran the truck with a "recording" Fluke meter and the highest recorded voltage was 14.69. I have cleaned all the grounds that I know of, the ones under the hood, and inside the cab on driverside footwell. Checked/cleaned all connections on the PCM, added an extra ground directly from #2 Battery to the PCM. Changed battery temp. probe, cleaned all battery cables and connections, including the one at the PDC. Took the covers off the steering column, found a broken wire going in to my ignition switch (acc. on A31) repaired it. Disconnected my brake controller. Did a gauge diagnostics, no faults. I drove it 80 miles yesterday and was perfect, but it went in to the "overcharge" 3 times today within 10 miles, then went another 20 or so perfect. I fell like it's a "grounding out" issue somewhere, right before it happens you can hear a popping sound in the stereo speakers, when it's in the "overcharge" state the dash lights will flicker and the headlight look to actually be flickering dimmer instead of brighter. Dealer doesn't feel like it's a PCM due to the intermittent issues, so I haven't gave it to them yet. I need HELP. Anyone else ever had such issues. Sorry for the long post but I think that just about sums it up, I may have done other things but my brain aint working so good.

 

Take the alternator off and go to autozone or advance auto parts and have them load test the alternator it sounds like the voltage regulator in the alternator. Also have them load test the batteries and have them put a electronic battery tester on them. You could possibly have a battery thats sulfated and grounding out but even if it was its not going to make voltage go up its gonna put a heavy load on the alternator making voltage drop.

 

Thanks, as stated above, batteries load test "great". As far as voltage regulature that is in the PCM, not the generator/altenator, that is why the Dealer said they don't think it's the PCM/voltage regulator they say when it goes it's not intermittent, it will either be over charge or under charge.

 

They may load test okay. Try and get them tested by a battery analyzer it can test for a dead cell and battery integrity. I would still have the alternator tested just my .02

 

Thanks I also did a specific gravity test, all cells checked great. I didn't have the alt. tested I just went a head and bought one and put it on. Made over a 400 mile run with my rock crawler in tow this past weekend and volt meter set right on 14V's and never had a spike, fingers are crossed that this corrects the issues.

 

Have you had any further issues?

 

alt diodes Are Semi conductors (not vacuum tubes) so they have what is called reverse leakage. (transistors too). this reverse current even small will Spike the zener current
regulator circuit. to some extent. So BEing a auto matic r46 torqueflight , does the tranny shift up and down at the same times ?? if not UNPLUG the alt feild wire connector.
hence my needle in my 2001 is drifting back and forth lately. hence i need a new diode pack & toss in a new noise filter (capasitor) block just to do it.
ultimately the battery is the True filter so have good true filters .
If all else fails on mine I'm gonna add 1/4 ohm resistors (high wattage) in series
to drop ,my overall feild power.