99 Chevy PCM bricked

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  • greasybob
    Senior Member
    • May 2008
    • 1590

    99 Chevy PCM bricked

    Well I haven't done that in a that in a while. Another shop sent a 99 K1500 5.7 over to have a used PCM installed and programmed. It got about 8000 bytes in and stalled out. Error unknown message. Hmmm ??? Probably a good reason that the GM shop turned down this job. You can buy refurbished PCMs with correct vin and software installed for about $100 bucks. A better option, maybe.
  • diesel71
    Senior Member
    • Feb 2008
    • 921

    #2
    yes, sometimes getting a preprogramed ones save time and headaches. once in awhile that's how we find out.

    Comment

    • jm43130
      Senior Member
      • Apr 2008
      • 182

      #3
      I had a Trailblazer PCM do that to me awhile ago. I was able to use my Tech2 in passthrough mode and it programmed it, even though MDI2 wouldn't.
      Even though programming stalled out, I didn't turn key off, just restarted whole process with Tech2 .

      Comment

      • bestdamgarage
        Member
        • Apr 2016
        • 99

        #4
        One older gms the pass through is to fast you need tech2.

        Comment

        • ToltecasChavez
          Senior Member
          • Apr 2011
          • 408

          #5
          Happens to me a ton. Once bricked, I keep trying to communicate with it until it goes through. Eventually the program sees the PCM and it'll take about another 2-3 times before it takes. Specially on those late 90's PCM.

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          • diesel71
            Senior Member
            • Feb 2008
            • 921

            #6
            Originally posted by bestdamgarage
            One older gms the pass through is to fast you need tech2.
            could you explain better? what do you mean to fast.

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            • Steve6911
              Moderator
              • Feb 2007
              • 2168

              #7
              Paul
              The communication is too fast and it bricks the PCM. I was once told to put the Pass-thru in debugging mode and then flash the PCM. Worked for me a few times when the Tech 2 was being used elsewhere. But using the Tech 2 is still the best method.



              see response 15 & 18
              Last edited by Steve6911; 01-02-2020, 11:01 AM.

              Comment

              • diesel71
                Senior Member
                • Feb 2008
                • 921

                #8
                Originally posted by Steve6911
                Paul
                The communication is too fast and it bricks the PCM. I once told to put the Pass-thru in debugging mode and then flash the PCM. Worked for me a few times when the Tech 2 was being used elsewhere. But using the Tech 2 is still the best method.



                see response 15 & 18
                thank you steve, good to know.

                Comment

                • greasybob
                  Senior Member
                  • May 2008
                  • 1590

                  #9
                  Throwing caution to the wind I got another used PCM. This time I tried the debug enable method, still no go. At least I did not fry the PCM this time. I got nothing on the progress bar after a couple of minutes then the error unknown message. Might try the Tech 2 later. Is there anything special to entering debug mode other than clicking on the enable tab ? I see no changes on the screen after doing so.

                  Comment

                  • DtechJon
                    Junior Member
                    • Apr 2015
                    • 8

                    #10
                    I have had this happen on some later model chevys maybe 2002-2003 and talked with product support at acdelco. I was told to disconnect batteries for ten minutes and try again. I don't know why but the power interruption restored communication and I was able to finish programming. fater reading some of the previous posts it almost sounds dangerous to shut the ignition off after an incomplete programming session but if after numerous attempts you can give this a try and hopefully it comes around.

                    Comment

                    • Ruston11
                      Member
                      • Feb 2015
                      • 40

                      #11
                      Fail

                      get a used one and dont program just do 30 minute theft relearn

                      Comment

                      • greasybob
                        Senior Member
                        • May 2008
                        • 1590

                        #12
                        So after frying the second PCM, this time using the debug mode on the PTP3, I finally found a used PCM with the correct software calibration and just did the 30 minute theft relearn. I would have tried that with the first 2 PCM but they were out of quite different vehicles. The PCM part no. covers a wide range from Cs, Ks, to S10s and Safari type vans.

                        Comment

                        • diesel71
                          Senior Member
                          • Feb 2008
                          • 921

                          #13
                          Originally posted by greasybob
                          So after frying the second PCM, this time using the debug mode on the PTP3, I finally found a used PCM with the correct software calibration and just did the 30 minute theft relearn. I would have tried that with the first 2 PCM but they were out of quite different vehicles. The PCM part no. covers a wide range from Cs, Ks, to S10s and Safari type vans.
                          you battled to the end and finally won

                          Comment

                          • greasybob
                            Senior Member
                            • May 2008
                            • 1590

                            #14
                            Sort of.... still would like to know why the failures. if it's a down load speed thing, can it be adjusted ? How does the PTP3 know how to handle the down load given different protocols.

                            Comment

                            • Glide
                              Senior Member
                              • Jan 2015
                              • 303

                              #15
                              Originally posted by greasybob
                              Sort of.... still would like to know why the failures. if it's a down load speed thing, can it be adjusted ? How does the PTP3 know how to handle the down load given different protocols.
                              Do you remember if the "current software" in the used ECMs had a asterisk next to them or if it said unknown calibration.If so the used ECMs may have had an aftermarket calibration in them.If that is the case,the aftermarket calibrations have write protection,so can't be overwritten.Any ECM that has been programmed with a programmer must be returned to stock before OEM programs will write.
                              I have quit buying used ECMs for Duramax equipped trucks because 90% of them have had programmers on them and so are garbage.
                              I won't comment on the speed as some people actually believe that.

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