Ive got a 2001 2500 5.9L cummins 6spd high output. Im expierencing overvoltage problems. When im driving the voltage gage spikes 18 volts for a couple minutes then it returns to 14 where it should be. So i replaced the alternator thinking it was the voltage regulator well that fixed it for about two weeks. It started doing it again so i bought a brand new alternator not a reman. one and two days later it still does it. I pulled the codes with my smarty and it said charging system too high and DTC in companion with JTEC module, What does that mean? So i cleared the codes! Anyway does anyone have any clue to what is causing this?