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Thread: 05 LLY ECM reading issues. I've tried everything!

  1. #1
    Tuner in Training
    Join Date
    Jun 2006
    LI, NY

    05 LLY ECM reading issues. I've tried everything!

    I own an 05 LLY CCSB that I purchased used. The truck has an aftermarket downpipe, exhaust, LBZ mouthpiece and what appears to be an EGR block off plate. Does not look like it has a fingerstick installed. I don't know if the ECM is tuned, however I don't think it is as the truck only has 20 psi of boost and feels as if it has stock power. When I try to read the ECM it fails with an x35 keycode error. I've searched the forum high and low. I have every TBC fuse pulled, info, radio and radio amp fuse pulled as well. The TCM and aftermarket remote start are disconnected also. I've tried it unchecking the fast mode box as well. I've updated to VCM editor 4.10.5 and am using an regular MPVI not MPVI2. What am I missing? Do you think ECM possibly being previously reflashed with EFI live would cause this issue? I have access to reflash the ECM with GM's factory software however do not want to do that if it is tuned in fear of causing a CEL if the EGR is blocked off. Any input would be greatly appreciated. Thanks.

  2. #2
    Advanced Tuner
    Join Date
    Aug 2016
    x35 means the seed/key algorithm has been modified and/or hpt is generating the incorrect key for this ECM for some reason. You can probably send a VCM Suite log to support and ask them about it.

    Alternatively, attempting to flash it with GM factory software would confirm or deny that the algorithm has been modified, but, as you said, you'll lose whatever you have in there.