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Thread: $0534 Unable to unlock previously autolocked LB7

  1. #1
    Lifetime Member vortecfcar's Avatar
    Join Date
    Apr 2007

    Default $0534 Unable to unlock previously autolocked LB7


    We have a situation where a customer who owns a V2 bought a .ctz file from us for his race truck. He full-flashed the file onto his truck. He is now trying to switch tunes but is running into trouble. He's managed to get the unlocked stock tune back on with a full flash but is unable to read the stock tune or to flash any other files over it. The starts and idles but on account of the mods is undriveable with the stock tune.

    Thanks for any help on this.

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  2. #2
    Junior Member
    Join Date
    Dec 2011


    I have seen this before. The part of the boot sector that holds the ecm id number becomes corrupted. I have had to send the ecm to have the eprom pulled and the chip erased and boot software reinstalled. It takes a few weeks but has worked. Tony at Ridgeruner mentioned there is some updates to the latest efi release to address this issue. I updated my software and have not had the problem sense. It always happens on lb7 ecm's when the problem occured.

  3. #3
    Forum tyhee Site Admin GMPX's Avatar
    Join Date
    Apr 2003


    Yes the LB7 is notorious for corrupting itself and losing VIN, Serial Number, Theft Data etc, on the early ones (01, 02) it is a 90% chance that if you flash it with GM's TIS the corruption will happen.
    The update we recently did was a change to the reflash routines to try to detect the serial number of the ECM better even if it had been corrupted. The few that were in this situation said that it did work.

    The screen shots show two problems, the easy one first.
    'Access denied' - EFILive V7.5 is not being run in administrator mode and Windows is not letting it write back some data to the programs directory. If you are logged in as the PC's administrator that shouldn't be an issue, if you aren't then right click the V7.5 icon and choose "Run as Administrator".

    'Invalid Serial Number' - It would appear the ECM has corrupted itself, have the customer try to tick all the options boxes in V8 apart from the Test Flash one and see if it goes through then. EFILive will attempt to unlock the ECM knowing the Seed/Key etc is likely corrupt.

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