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Thread: Replace TCM instruction question for unlocked T87A

  1. #1

    Replace TCM instruction question for unlocked T87A

    I posted this question in a different section but I am hoping to get an answer or advice quicker here.

    I have a truck that we swapped an LT4 with 10 speed into and did not have the original ECM and TCM. I purchased a new E92a and had the LT4s VIN programmed into it with GM software and purchased the unlocked T87a from HPTuners with the same VIN that I used in the ECM.

    Since I do not have the original TCM, can I just plug in the unlocked TCM without following the replace TCM process?

  2. #2
    Tuner in Training Chase08's Avatar
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    I would ask HPT

  3. #3
    Advanced Tuner IARLLC's Avatar
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    The "replace TCM process" that you refer to must take your transmission's solenoid data from the old TCM to transfer it to your new TCM. Since you don't have the old TCM, the solenoid data from your transmission probably has to be installed in your new TCM via SPS GM programming. This is no longer a dealer only process. There are a lot of competent techs out there that can handle this process for you if you don't have an MDI or Mongoose.

  4. #4
    Quote Originally Posted by IARLLC View Post
    The "replace TCM process" that you refer to must take your transmission's solenoid data from the old TCM to transfer it to your new TCM. Since you don't have the old TCM, the solenoid data from your transmission probably has to be installed in your new TCM via SPS GM programming. This is no longer a dealer only process. There are a lot of competent techs out there that can handle this process for you if you don't have an MDI or Mongoose.
    So will reprogramming the TCM with SPS lock the TCM that is currently unlocked from HPT? I have a MDI so reprogramming isn't a problem. Just not sure if it will reencrypt the TCM

  5. #5
    Advanced Tuner TheMechanic's Avatar
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    Quote Originally Posted by IARLLC View Post
    The "replace TCM process" that you refer to must take your transmission's solenoid data from the old TCM to transfer it to your new TCM. Since you don't have the old TCM, the solenoid data from your transmission probably has to be installed in your new TCM via SPS GM programming. This is no longer a dealer only process. There are a lot of competent techs out there that can handle this process for you if you don't have an MDI or Mongoose.
    Have done several TCM programmings and haven't used the old TCM on replacement. Some ask for the info on the tag of the trans that is going in but that's about it. Personally programmed maybe 30 to 40 of them so far. Using Techline Connect with MDI2

  6. #6
    Cool deal guys. Thanks for the help. I heard back from HTP and they confirmed that programming the T87a after it is unlocked will not relock it. That was my main concern since this is the first 10 spd vehicle im working on without the original controllers