Usually this sort of problem is what i do well. This thing is throwing me for a loop. 2002 dodge dakota 4.7l auto 4wd 150k. Died while driving. No bus message on instrument cluster. Found where the pcm grounds are supposed to be rotted away. Put new ground wires on, checked all other powers and grounds, everything checked good. Could talk to all other modules with scan tool. Still could not talk to pcm and truck would not run. Got a pcm off ebay all programmed. Put it in, truck runs and i can talk to pcm with scan tool, however cannot-talk to instrument cluster and still get the no-bus, no gauges work. Put the old pcm in and truck does not run, and i cannot talk to pcm, however can talk to instrument cluster. I assume the new pcm is bad somehow, but it doesnt really make sense. Anybody seen anything like this? What the heck am i missing?

Thanks

Does the new PCM need to be set/programmed specific to your VIN?

Does the correct mileage show on the odometer with the new PCM or just "no bus"?

When I had to replace the PCM on my '96 Dak, the guy needed my VIN #. It was an ebay purchase from an outfit in south Florida; can't remember their name.

If it helps. From PCM to Data Link connector to the scan tool will use the SCI wires to communicate with the PCM only. All other modules including the PCM share the PCI wiring. So a defective PCM could be pulling down the PCI causing no bus. I recently used a aftermarket PCM on a Jeep and had the same type issues, the third PCM fixed it after lots and lots of hours looking for something other than the pcm as the cause!

Likely a bad new PCM. I went through two from the "outfit in Florida" before they got it right. First one died on the second start, second had Cal Emissions for a 49-state truck. Third one also died about a year later. My suspicion is that they got something wrong in the program on yours. They are good about returns...

I've got some spare 5.2 and 5.9 computers ('96-99). I can run my 2000 5.9 on any of them, but I get the NO BUS in the cluster...

Odometer is correct. I am leaning towards a bad pcm as well. I am very leary of diagnosing as a bad pcm to begin with because very rarely does a pcm go bad. This one came from flordia as well. I sent them an email, hopefully i get a response soon.

You bet, that's my understanding too. Your other one probably got a surge or something because of your wiring. As long as your mileage is still there, I bet another factory PCM from the local autowrecker will get you up and running without issue.

If you get one from a JY make sure the truck does not need a grey key, if it does your truck will not run with it.

This sounds right. Also make sure they gave you the right year PCM. I do remember some years with Neon's and Dakota's I had to go into the scann tool and turn on internal bus voltage so the scann tool could talk to the other modules other then the PCM so if its the wrong year PCM it may also cause that problem. And thats because the PCM is on the SCI circuit as was said and the other modules are on the PCI bus or which ever bus it used that year. We always went into the PCM and put the VIN in also as we would program it in with the scann tool. If it had skim then I would go into the skim module and program the vin in that module as you could also transfer the vin through the skim module. Ron