Alternator or computer?
 

I have a 2002 dodge ram 2500 24v and it is showing like the alternator is going out on it. I change the alternator and it didn't fix it so i had the old one tested and it was still good. I was wonder if it could be the computer that is bad ? And is this a common problem on a dodge? Any advise on what it is and what to do would be great thanks.

You need to buy yourself a code reader.

How many volts do you have at the batteries? Should be 14.4~14.4V iirc.

well thats the thing it surges from 14.5 down to 10 or 11 and it just keeps going up and down thats why i am cunfused on it. And my truck isn't reading any codes on it.

hey i just had that problem myself.. my problem is the wire that plugs in the back of the alternator had to be in a certain spot to charge, i could wiggle it and hear the motor bog down so i had to put a zip tie off to the side and works 100% now

If the grid heaters are cycling this will likely affect the charge rate and cause this surging. Have you checked the voltage once the truck is warm and the grid heaters have stopped cycling?

The pcm (or whatever you want to call it) controls the charge rate. You can wire in an external voltage regulator instead of replacing the computer if you can determine thats where the problem is.

I would look at replacing that wire - its likely broken on the inside of the insulation. Tying up a wire isnt a good fix.

even when the truck is warm it still surges up and down and it is in limp mode right now i dont know exactly what that means. And if there is anyway to get my truck out of it.

i will as soon as funds are available right now i drive it like once a month, i drive the ol beater ford to work