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Thread: Killed two GenIII PCMs in a row.

  1. #1
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    Default Killed two GenIII PCMs in a row.

    I'm finishing a gen111 5.3/ 60E swap and I've lost two PCMs during reflash. The first was during a cal only flash, second was during full reflash (replacement PCM). In both instances all appeared normal until the software attempted to reboot the PCM. During both failures I noticed that the software attempted the reboot 7 times before saying ok. Turn the key off for 15 seconds and attempt to start the engine.

    The fuel pump only primes for a split second (unlike the usual 3 second prime), no start and no communication. The scan tool does not recognize the PCM, no read or write in the tune tool.

    I've read the threads returned from searching "dead" and it seems that PCMs falling into a "dead poll" state is not too uncommon but my symptoms don't appear to be those of dead poll. When trying to read or write, the software is unable to determine the "status" of the PCM.

    I should mention that I have driven this vehicle before I began editing the original cal. In fact I was able to do three or four cal only reflashes before the first PCM failed. Today, I installed a used replacement PCM and attempted to full flash it once and it failed. On the initial KOEO, the fuel pump primed normally so I'm certain the PCM was in working condition before the full reflash.

    I'm two PCMs and licenses deep and can't afford to try again unless I find something that may have caused these failures. Also the orange LED on the FS V1 does blink during communication attemp, however it is something like 1-2 times per second instead of 4.

    What can I do to ensure a successful third attempt? Bench top harness? Thanks guys! This is getting costly!

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    I'm not sure if this is relevant or not but when the first PCM failed I had just changed the vehicle speed sensor pulses per mile from 4000 to 1000; my attempt at compensating for a mechanical, speedo gear driven VSS that is sending much fewer pulses/ rev than the oe 40 tooth reluctor.

    I read a comment that Blacky made stating that a cal only reflash cannot "brick" a pcm( unless certain parameters are set outside their legal range). I wonder what he meant by legal range and if this pid could be one of those "certain" parameters?

    Again, the first PCM failed during a cal only reflash.

  3. #3
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    changing some parameters surrounding the speedo into a range too far away from their stock values can make the PCM go into a continous loop effectively bricking them.

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    Really!?!? Why do we have access to parameters that if changed will brick a controller? Are there other parameters like this? Can all the other speedo parameters be changed? Does anyone even have a list of "deadly" parameters? This has me scared to death to do anything. I must get around this VSS issue one way or another. Thanks for your time!

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    Electronic Speedo Corrector and feed the PCM something within it's range?

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    Quote Originally Posted by vortecyota View Post
    Really!?!? Why do we have access to parameters that if changed will brick a controller?
    A valid question, we do have some upper and lower 'sanity' limiters in there, you'll notice it's set to 100 as the minimum. We did some in house 'brick' tests and found that value to be the lowest that we could go before the PCM bricked itself. They are bricked, we can replace any licenses you have used on them though. Was it H0101 you were changing?

    Quote Originally Posted by vortecyota View Post
    Are there other parameters like this?
    With speedo stuff yes, but we did try to cover them off with lower and upper limiters that in our testing prevented bricking.


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    Actually it was {H0105} EFILive limits are 0-131070. I went from 4000 to 1000. Thank you GMPX! That would be a great help and I will be very appreciative! Is there any other info you would like from me?

    I would love to learn more on this subject so that I can keep from bricking anymore PCMs. Is there a list anywhere or is there mystery surrounding this?

    Are any of the other pids safe to edit in order to get this Trans to shift? Currently at approx 45MPH the PCM is calculating 1 to 2 MPH.

    I just realized that {H0105} isn't even going to help me. It looks like {H0104} is where I need to tweak. Is that one safe as long as I stay within EFILive's limits? Thanks again for your time!
    Last edited by vortecyota; May 27th, 2013 at 01:36 AM.

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    I installed the PCM out of my personal truck (already licensed) in this 72 truck and got everything working well. I believe it was a combo of H0101, H0102, and H0104 that got my VSS calculation in line. Now I just need to grab another PCM, license it and I can have my personal PCM back, lol.

  9. #9
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    If you just send a message to support@efilive.com with reference to this thread they'll get you sorted with the license.


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    RoadRunner....
    "All that is needed for the triumph of evil is that good men do nothing..."

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