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Thread: LMM Programming History & CVN's Explained

  1. #121
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    Well F#$%!
    '07 LBZ Classic, BW S464 Turbo, EGR deleted, 3" IC piping, Trans-go, ATS 5-star converter, stock clutches

  2. #122
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    Quote Originally Posted by LBZ View Post
    Well F#$%!
    Same thing I thought lol, I tried a 'mileage' tune in mine last year when diesel was 5.00 a gallon, since I already had EF!live for my LS1 car I figured why not try it on the LBZ. It didnt do anything really so I put it back to stock a week or so later.

    So last week I was bored, reading around this site and noticed this thread. After seeing the last post I took my truck to a friend at a local dealer and had him check the CVN numbers on all the segments and one was wrong. Even though I flashed the stock tune back in a year ago and the truck has never been to the dealer or programmed since.

    The 'Engine' segment (PN 12610878) CVN was wrong. I assume since EFIlive tune says its not used you cant even change anything in it so I have no idea why it changed. The 'engine' checksum on EFIlive from my original read and the one in the truck were different as well, I have no idea why or how. I flashed the original stock tune again and now all the checksums in EFIlive are back to the same as the original read. I am going to check it again on a tech 2 soon and see if all the CVNs match. I read/flashed it with one of the first releases of EFIlive for the LBZ so maybe thats how it got messed up, I had to re-save the .tun file before it would let me flash it in with the lastest EFIlive release.

  3. #123
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    Quote Originally Posted by kp View Post
    I am going to check it again on a tech 2 soon and see if all the CVNs match. I read/flashed it with one of the first releases of EFIlive for the LBZ so maybe thats how it got messed up, I had to re-save the .tun file before it would let me flash it in with the lastest EFIlive release.

    Can you please let us know how this turns out?
    '07 LBZ Classic, BW S464 Turbo, EGR deleted, 3" IC piping, Trans-go, ATS 5-star converter, stock clutches

  4. #124
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    Quote Originally Posted by LBZ View Post
    Can you please let us know how this turns out?
    Not real high priority since there is nothing wrong with the truck so it may be a while. I was hoping I was missing something and there was a way to see the CVNs in EFIlive and save me a 100 mile round trip but I guess not.

  5. #125
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    No problem. Whenever you or someone else can check this it would be nice if it could be shared-no rush!
    '07 LBZ Classic, BW S464 Turbo, EGR deleted, 3" IC piping, Trans-go, ATS 5-star converter, stock clutches

  6. #126
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    Went there this afternoon and did the GM procedure with the tech 2 and two CVNs didnt match. The 'engine' and 'CPU' segment were both different. Downloaded a couple stock tunes from dieselplace and then some others didnt match. I then did a full reflash with the original file I took from mine and the same 2 CVNs didnt match.

    To sum it up, on my LBZ putting the stock tune back in will NOT pass all the CVN segment checks on a tech 2 as described in the bulletin on post 117.

    Your results may vary of course and dont use this as absolute fact, maybe someone else will try it and verify it. I didnt want the newest OS flashed in so I just left it, I'm out of warranty soon on miles anyhow but I'm sure many arent..

  7. #127
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    Ok thanks for the heads up. I guess I should buy a new ECM from GM then.
    '07 LBZ Classic, BW S464 Turbo, EGR deleted, 3" IC piping, Trans-go, ATS 5-star converter, stock clutches

  8. #128
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    Quote Originally Posted by LBZ View Post
    Ok thanks for the heads up. I guess I should buy a new ECM from GM then.
    Like I said dont take my word for it, since I read my stock OS with the earliest LBZ software maybe something got screwed up along the way. Its funny though the one segment that was always off with no matter what I loaded in was the 'engine' one and according to EFIlive that isnt even used.

    I would wait until someone else with a tech 2 and LBZ tries this before buying a new ECM.

  9. #129
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    The one segment that was different was likely the one you changed for the mileage test proving that CVN counts are stored and can be recalled by GM. I think your test was perfect!
    '07 LBZ Classic, BW S464 Turbo, EGR deleted, 3" IC piping, Trans-go, ATS 5-star converter, stock clutches

  10. #130
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    Quote Originally Posted by LBZ View Post
    The one segment that was different was likely the one you changed for the mileage test proving that CVN counts are stored and can be recalled by GM. I think your test was perfect!
    I dont think multiple counts are stored or retrieveable like an LMM, the CVN is just a CRC, all it takes is one bit of data to be off and the number doesnt match. There was no way to retrieve any previous flashes, even with the MDI, just the segments/CVN list with the tech 2. The procedure for the LBZ is to retrieve the calbration part numbers from TIS, print them out, take the tech 2 and printout to the truck and manually check each CVN against the PN.

    Easiest thing to do would be if you have an older OS just pay to have the neswest OS flashed in and dont touch it after that and swap another PCM in to tune on. At least the LBZ guys can fix it with a GM reflash I assume, the LMM guys are screwed.

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