before i did the fuse trick i drove about 77 miles then blow the new pcm. after that i put a new pcm in and then the fuse protector and drove another 81 miles blow the fuse agian but it saved the pcm. if it runs for about 10 minutes then look at the alternator. that gen curciut runs through that series of wires. none of the issues are the same i have found. i pealed back every wire loom and look at every wire. what a pain. but my issue i know is in a component not a wire.

 

Thanks for the heads up. I have the same problem. I am putting in an external voltage regulator, in case it's the alternator, but I have been told by an ASE certified 20 + year dodge technician that it is not likely. That doesn't mean it can't happen.I'll also fuse the ASD gr/or wire. I'll keep you all up to date, and appreciate if you could do the same. Great forum. Thanks everybody. Ray

 

Had the same symptoms, blew out 2 PCM's. Took it to the local mechanic and he had it apart for days running down wire diagrams. Told me he had fixed it so I drove it 60 miles back home and it then blew out my 3rd PCM. At this point I decided to search the net and found this site.

FIX: I put in the 3 amp fuse and was able to drive it until I heard the tell tail sign of a rattle coming from the front of the engine. It was the alternator (generator on 2000 Dodge Ram 1500). I had the alternator looked at and the race had slipped out due to the tensioner being out of whack and it was making contact with the brushes. I have since driven the truck over 800 miles and have not had an issue.

I have kept the fuse in just in case. I was thinking of going to an auto-reset 5 amp later. (if anyone has any advice on this I would like to hear it)

Also, for us California folks, you might want to pick up a used PCM if you have the Cali-Emissions model. Having to buy 4 PCM's I learned that my truck runs unbelievably well with the federal model. I plan to put back in the Cali model when DMV requires another smog cert.

 

I had a 3 amp fuse in and it blew once, but i fried the pcm and never blew the fuse. I had thrown bad governor pressure sensor/ bad governor solenoid code. Could that have fried the pcm through the 5 volt circuit? Can that 5v. circuit be fused to the pcm. If yes what wire and what size fuse. I have replaced the gov. sensor and solenoid. I started the truck but didn't drive it.I would like to protect the 5 v. circuit.

 

The PCM actually supplies that five volt circuit. And I do believe there are several of them.......

What is it you are attempting to do?

 

I thought the pcm supplied the 5 volt circuit. I was just trying to see if I could save my pcm. I had a fuse in the 12volt line , but blew my pcm anyway. I know I had a bad gov. pressure sensor and solenoid when the pcm fried. It didn't blow the fuse though. I replaced them, and put a new pcm. I have started it but haven't driven it yet. The last one blew when the transmission shifted. I guess I just have to drive it and see. How many amps should the 12 volt line have. I put a 3 amp, but I've read where people said 5 amp would do it.

 

There are several 12 volt sources for the PCM. They are already fused as well....... Once voltage gets to the PCM though, you lose control. If one of the circuits the PCM plays with (and there are both 5-8 volt, and 12 volt circuits) shorts, it can indeed fry the pcm. But, for the most part, on 'control' circuits, the PCM just supplies a ground path.

Did you replace the pressures sensor/solenoid?

 

Yes I did replace the sensor and solenoid. I also adjusted the bands. I put the new pcm in and started it. I ran it for about an hour and put it in drive and 1st and 2nd. It shifted in fine . I drove it back and forth around the yard and it seemed ok. Even though I replaced them and that was my original problem it seems, I guess I'm a little gun shy and just wanted to protect everything I can. Well I have a fuse in the 12v. feed so I guess that is all I can do. So taking it for a drive is the next step. I will let you know how it goes. I bought plenty of 3 amp fuses. LOL

 

OK so I got the dreaded P1389 code, Let's start by truck would randomly shut down, couple times while driving, couple times while sitting still, so finally got the code and started with the ASD Relay, it looked burnt on the one terminal, bench tested the Relay it's working fine, swapped it out with a new one anyway, what I'm really looking for is wiring prints of this beast, I really like the idea of an inline fuse before frying my pcm.. Any info on wiring diagrams would be great thanks

 

You can grab a pdf version of the factory service manual from here. Wiring diagrams are in section 8W.

Welcome to DF!