Edmunds Answers

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  • avatar MrShift@Edmunds 06/13/10 3:26 pm PST

    My feeling (logic?) is that if an electrical component is ittermittent, then testing it won't work either, because it will probably only reveal the self-evident--that sometimes it works and sometimes it doesn't. I suppose the manufacturer could reverse engineer it and find the EXACT problem but I think this in-depth level of diagnosis is not within the equipment means of the garage mechanic.

    Have you ever read this crazy scenario from another Dodge owner?

    No Bus Error SOLVED

    I also think that replacing the PCM is not a reckless move at all---it's as likely as most explanations. Too bad it's probably a non-refundable item. Don't you have to program these after installation? That sounds like *more* money. Ugh!

Answers

  • karjunkie 06/13/10 10:44 am PST

    Before you assume the PCM is bad, why don't you tell us your symptoms as it is probably something much simpler. A complete PCM diagnostic would require a trip to the dealer which I'm sure you'd like to avoid.

  • MrShift@Edmunds 06/13/10 10:48 am PST

    You may be barking up the wrong tree here because the PCM will shut down the fuel system if it does not get proper signals from various sensors---one guess would be your crankshaft positioning sensor.

    You'd best have the car scanned for trouble codes and this might give you some hints as to where to start looking.

  • jpinazle 06/13/10 11:09 am PST

    Karjunkie. First of all, thanks for the quick responce. I'm not assuming its bad. I just want to know if there is a way to test it. This has been an on going problem for months now. This is one of the "no bus" issues that seem to be quite popular with the dodge pickups and durangos. I have been though this with my mechanic. I have read tons of forums, and have tried every logical suggestion offered. I have narrowed it down to either, the pcm gets hot and shuts engine down or , the harness connection, wich I dont think is the case because I have inspected pretty thouroghly and have even tried adding extra insulation. Here is what I do know. The problem has no consistancy, other than heat. I can drive 200 miles over a couple of days in 96 degree weather and not have a issue. I can drive 10 miles in 80 degree
    weather and stall 3 or 4 times over the next 20 miles. The only thing that seems consistant is the heat around the pcm, ie. pcm, firewall, a/c dryer and lines(a/c NOT on). I dont want to have to replace the pcm but i am running out of ideas.

  • jpinazle 06/13/10 11:15 am PST

    mrshiftright. thanks, you are correct. it does shut the fuel system down. i have tested for codes several times and get none, other than the nobus message. but that is what is happening it seems. the pcm gets hot and shuts the fuel system off.

  • MrShift@Edmunds 06/13/10 2:09 pm PST

    Well it's a tough call then. I'd be more inclined to dig deeper into the harness, checking the continuity of each connector for bad grounding, etc. Of course, this requires so much time that paying someone to diagnose all of it might end up costing more than the wild *** guess of throwing $400 bucks on a new PCM.

    What's the code # you are getting?


  • jpinazle 06/13/10 3:14 pm PST

    thanks again, mr shiftright. your wild guess, by the way, is right on, ($400). i THINK i've done a pretty thourough job with the harness. I'm just not sure, with all the inconsistancy of this problem, the more things i try, the more frustrated and confused i seem to get. lol I worry because, all the trouble shooting i do, at least in regards to connections and wiring have been done under "cold engine" circumstances. could conditions such as continuity change under "hot" conditions? Also, in answer to your question. I am not getting ANY codes at all. Just the (from what i've been reading) all to common " no bus" message that displays on the odometer after the truck stalls. one of the more common issues i have read about in relation to my problem lies in the middle connector of the pcm. but no one could confirm either the connector or the pcm being the problem. but they could wiggle the connection after stall and that would allow engine to restart. this worked for me a few times but now that doesnt seem to work at all. iv'e inspected the connector and it appears to be fine. i even shot a little dielectric greese into the connector ports with a syringe. still doesnt appear to help. that is why im thinking it may be the pcm itself. maybe something that happens to the circuit board under heat? Can the pcm be tested some way? and if so, does it have to be on the truck in order to do so?

  • MrShift@Edmunds 06/13/10 3:26 pm PST

    My feeling (logic?) is that if an electrical component is ittermittent, then testing it won't work either, because it will probably only reveal the self-evident--that sometimes it works and sometimes it doesn't. I suppose the manufacturer could reverse engineer it and find the EXACT problem but I think this in-depth level of diagnosis is not within the equipment means of the garage mechanic.

    Have you ever read this crazy scenario from another Dodge owner?

    No Bus Error SOLVED

    I also think that replacing the PCM is not a reckless move at all---it's as likely as most explanations. Too bad it's probably a non-refundable item. Don't you have to program these after installation? That sounds like *more* money. Ugh!

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