Okay. This is wierd. 2001 dodge ram 1500 4x2 5.9 magnum. Truck sat up for a few months. Now the electrical system is acting funny. Crank the truck. Cranks fine. Voltage output is lower than should be 11.7 with a voltage meter at the battery post. I know that's low. The Guage shows somewhere around 12. As long as the truck is still it will maintain that no matter what the drain is. When I put the truck in drive and TAKE IT UP A HILL, the voltage guage pegs out below 8 and I assume the truck quits charging because about 30 min later the battery is completely dead if left going. I kill the truck immediately after the needle pegs out and recrant it , the needle returns to the right voltage and I assume it starts charging again because I left it running with the lights on, ac going, and radio blaring and it remains charged. Any suggestions what this is?

 

I would pull your alternator and have it checked at a parts store. Because if it isn't the alt then it is something in the PCM. Your voltage regulator is in the PCM.

 

My money is on the alternator.

 

Tested the alternator. It's good. Put a voltage tester on the battery when the guage bottomed out. No change in voltage. So my question is what would kill the voltage guage with good voltage still on the system. And why does it do it going up a hill. Any suggestions.

 

The answer to both questions: Wiring fault. When it's not acting up move conductors around while someone watches the gauge. You shouldn't need to start the engine to invoke the failure -- if you do, be very, very careful to avoid injury.

 

I figured as much. I chased down every wire I could in the circuit. Wiggled every wire I could think of. No change in outcome. Runs perfect parked. I can only get it to short out in drive "GOING UP A HILL." I don't have a clue what this is.

Now my theory was that the fluid in the battery was being shifted when I went up a hill but it did the same thing with a different battery. So my next theory was that an oil filled solenoid was low on oil and tripping when going up a hill but there are no oil based solenoids in that circuit. Any other suggestions. I understand that shorts are a pain and can be dangerous. But I am describing a pattern that I have witnessed and asked numerous people and no one can come up with a good answer or some more test to tell me to narrow down the problem. And I am not going to take it to a stealership to let them charge me for 20 hours worth of labor trying to figure this puzzle out and not come up with a solution. I am not trying to bash on anyone here and I am extremely appreciative for all the replies Just trying to come up with answers

 

Once the failure presents itself on a hill, if you pull over and stop, (still on the hill) does the problem remain? Or go away?

 

You tested the Alt how? Are you saying that you checked it with the battery connected and you had voltage and then again when it was acting up you checked it again with the battery connected and now you had no voltage?

I have another idea and that is that you might have a bad battery. Again you need to pull the battery and take it to an auto parts store to have it tested. I would pull the battery and alt and take both in to have tested.

 

You have two conflicting statements. So is it charging when the gauge is reading 8 volts or not? May try cleaning all the battery connections and grounds then see what it does.

 

It goes away till I put it in drive and move a little bit.

I have put two different batteries in the truck and had same problem. I pulled the alternator and took it to a shop to be tested. The shop stated it was good.

Let me clarify. When the battery guage drops below 8, the truck apparently quits charging (I'm assuming the pcm controlled switch gets shut off. I don't know exactly. I just know the battery will eventually go dead from the engine electronics running). The battery will still read the same voltage as the needle was before it bottomed out until it runs dead of course if the problem doesn't get reset.