Ok here is what i have, 2001 2500 4x4 5.9L cummins. Straight out of the alt. with is unhooked from the 140amp fuse link I have 36V on a multi-meter. If I hook it up like it should be the volts drop to 12 and the wire from the alt starts to melt down. The volt on the dash gauge goes to normal 14v. I have replace the alt. and the pcm. Thanks for any help!!!

 

I would check the field wire for a short to ground. Unhook the field wire and with the engine off put a DVM set to ohms and/or continuity and see if there is a reading. There should not be any reading or a very high ohm reading. If 0 or low ohm reading then the wire is shorted and needs replaced.

A shorted out (grounding) field wire will cause the alternator to go to full output, which will burn out the alternator and can melt wires.

 

I checked the field wire and it is not shorted to ground. Thanks for the check. Any more ideas