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Thread: New built 6L80 TCM communication issue

  1. #1
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    New built 6L80 TCM communication issue

    Hey guys. I'm new to the 6L80 but not new to transmission tuning. I've got some experience in the older 4L60 and 4L80 platforms. I'm nearing the end of a project and running into some issues. here's the story:

    My 2013 Escalade EXT wasted the trans with my wife driving it months ago. I didn't trust any local builders with this trans, so I loaded it up and drove 2 hrs to Gearstar Performance Transmission in Akron OH. It took them a few months to get it done, and then when I picked it up, I realized they got me the wrong torque converter. So another month passed and I finally got my 2800 triple disc from Yank. While the truck was down, I performed a DOD and VVT delete, changed out the cam/valve springs and re-gasketed the L94. I just put it all back together, read the ECM, TCM, FSCM, and wrote in a few modifications to compensate for the DOD/VVT, and a couple changes to the PE values. Now I go to fire it up and the engine runs flawlessly, but I'm getting the following DTCs: P0700-Transmission control system, U0101 Lost communication with TCM, P0602 PCM programming error. I can't clear these codes, and when the transmission is put into gear, I have reverse, and what feels like 3rd gear. I haven't driven it down the road, just moved it to the other side of the shop. I've double and triple checked all of the connections, and tried disconnecting the battery to fully reset the controllers, and still getting the same thing. I'm also getting stability control and traction control errors on the dash, and the PRNDL display on the dash doesn't show any gear selection when you move the shifter.

    I was told by the builder to send them a tune file so they could make the changes required for the new transmission and converter, but now it's been over 2 weeks and they're giving me the run-around.

    So my question is: Is there any reason that a new valvebody/TCM would be able to be read and written, but not not communicate on the BUS and not at least be able to go into gear and shift as the factory intended? Is there a special flash procedure that needs to be performed on a brand new TCM, before it can be recognized by the other modules? Is it possible that my builder installed a part that isn't compatible with the rest of the system?

    Any insight on this is appreciated. I need to get this thing back in service! Thanks

  2. #2
    Tuning Addict 5FDP's Avatar
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    I believe a new TCM has to be flashed to match the OS that the PCM is running. So a dealership level scan tool would flash the TCM with the correct file that came with it from the factory. Then you could start tuning it as normal.


    This is why you couldn't grab say a 2010 6L80e from a junkyard and slap it in a 2013 vehicle and have it just be plug and play.
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

  3. #3
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    Quote Originally Posted by 5FDP View Post
    I believe a new TCM has to be flashed to match the OS that the PCM is running. So a dealership level scan tool would flash the TCM with the correct file that came with it from the factory. Then you could start tuning it as normal.


    This is why you couldn't grab say a 2010 6L80e from a junkyard and slap it in a 2013 vehicle and have it just be plug and play.
    I suspected that this could be the case. Can anyone that's been through this confirm?

  4. #4
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    Alright. Now that I know the nature of the issue, I've confirmed the following: For the new TCM to be functional, the correct VIN and OS need to be flashed in with the GM MDI tool, or SPS software. So it looks like it's getting towed to the dealer. Hopefully that goes okay, as I've had issues with modified vehicles at the dealer before.

    Also: Is there any benefit to having the dealer do the fast adapt learn procedure while it's there, as opposed to doing it myself in the VCM scanner?
    Last edited by Cadtorque; 02-11-2019 at 08:34 AM.

  5. #5
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    The fast learn doesnt work ...and yes 100% the problem your having is an TCM without a program

  6. #6
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    Kinda stuck in the same place . I have 2013 Escalade trans. running it with a 2010 Camaro ECU and getting error on TCM trying to rewrite Camaro software to the old TCM in the trans.
    Is using a GM MDI tool through a dealer the only way to resolve this issue ?