Recently had an issue with the PCM overheating and the truck shutting off. Thought it was the fuel pump but traced it down to the PCM. Got a reman one ordered based on my VIN and it was an easy replacement. Now I burned up 2 alternators. The only thing I can think of is that it's something to do with the PCM.
My original one was a big beefy metal bound brick but the new one they sent me and alot of them I see are more narrow and maybe metal and plastic. I'm wondering if the hardware itself is different with the old one having a voltage regulator in it. This one will let the truck run fine, but the voltage shows near 8v when running and then will drop to zero (i think this is the thermal shutdown on the alternator). This happened on my original alternator and then a replacement alternator (only went about a mile before the alternator was smoking and toasted). Does anyone know if there was a change in the hardware of the pcm from the 2000 year model? I'm thinking this could be a redesign that fits and has the same programming but wont handle the voltage correctly. I even switched out with another identical reman box that is brand new and had the same issue.

 

Voltage regulator is in the PCM. Yep. If your original wasn't giving you any charging problems, then it likely IS the PCM that is smokin' 'em. What is your volt gauge showing at idle, and then at 1500 RPM?

 

I have the same issue with charging.I have had the alternator tested and of course it tested good.My voart the enginelt gauge reads around 11 volts when I first start it, but drops to 0. I have read the voltage with a meter, and is constantly arounf 11 volts. Bad PCM?

 

Yep. Bad PCM. (voltage regulator.)

 

Follow up to this..... After I replaced the PCM, the original alternator went out and wasn't showing it charging. After replacing the alternator, the new one quickly burnt out which made me think that it was the PCM and voltage regulator. 2nd new alternator and having similar symptoms. The timing made me think everything was related to the PCM, however I know that I was using a deep cycle battery instead of a normal truck battery and that I got the big alternator without knowing what size i had before. I was about to change out the battery with a different one when I went through the charging circuit and found that I blew the 140A bolt in fuse for the alternator. Fixed that and now everything is working right. If it happened at a different time, I don't think I would have jumped to the PCM but at least I was able to figure it out. @Tom Martin , not sure what truck you have but I do have another replacement PCM that I got off ebay to try. Ended up not being the issue, so I just have a spare now that I'm willing to part with.