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Thread: T87A controller versus T87

  1. #1

    T87A controller versus T87 important news!!

    Found in my testing is that I can run the earlier T87 in place of the T87A. This is great since the T87a is encrypted. I have been running a T87 from a 2015 silverado OS on a 2017 silverado ECU...This is in hot rod swap.
    Last edited by vannatta20; 01-05-2019 at 05:22 PM.

  2. #2
    Advanced Tuner IARLLC's Avatar
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    Thanks for the heads-up! This is great for many of us! Did you flash the T87 to the 2017 VIN with ACDelco TDS? Or did it play nice with the newer PCM? Just curious for a LARGE group of Denalis that CANNOT have lights flashing on the dash. Also for licensing... How did you read and license that TCM? Under the 2017 PCM/VIN just like a 2016? I have of course only ever read and licensed 2017 and 2018 rigs the (new) normal way which does not even seem to read the trans info because it is locked. So?

    Thanks again!

  3. #3
    We just took the T87 from a used 2015 vehicle and stuck in the 2017 swap. We already licensed the 2017 ECU of course. I would think it would play nice in a factory vehicle too. We didn't have time to mail off the T87A controller to get unlocked. When you do a full read the t87 shows up in the file with the 2017 ECU. I usually get in trouble for sticking something where it does not belong but this time it worked out.

  4. #4
    Advanced Tuner IARLLC's Avatar
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    AWESOME! THANKS AGAIN for the GOOD NEWS! When GEN5 rigs came out GM gave all kinds of warnings about not swapping modules. Even a transfer case module from another (same year, same model) rig would cause a no-start until transfer case position was learned. Makes sense. Some of the GEN5 modules have to have the same VIN in order to connect with each other and some do not.

    I don't have them all figured out yet but had to do a LOT of experimenting with TCCMs, BCMs, Radios, Instrument Panels, etc over the last few years to set up a bunch of 15-18 Denalis EXACTLY the way a very special client wanted (without GM cooperation). Would have been a lot easier if ACDelco TDS still had a clue but they seem to hire less and less competent people combined with less helpful policies... If we ever figure out how to "tune" BCMs there are a few more things I'll change but for now this client is happy.

    Right now I have 2 2017s and 1 2018 Rally truck that needs the TCMs tuned but that client won't let me send out the TCMs for unlocking and has not agreed to buy prepped TCMs yet so maybe I can buy some used 8 speed TCMs from 2015.5 or 2016 rigs and give them a try. Will update if I ever get approval for that move.

  5. #5
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    To clarify, while the T87 and T87A are pin-compatible, and use the same CPU, they are not 100% interchangeable. The T87A brought TWO things to us - a secure boot loader (which is why they need be unlocked) and also electrical support for the 9 speed and 10 speed automatic transmissions.

    You cannot flash a T87 with T87A software, or vice-versa. If you want to use a T87 in place of a T87A, you need to find a T87 application that is relatively similar to your T87A application. In other words, if you have a T87A-equipped 2017 Silverado with the 6.2L engine, 8sp transmission and 4WD, you can PROBABLY swap in a T87 from a 2016 Silverado with the 6.2L engine, 8sp transmission, and 4WD without issue - running the OE 2016 Silverado software.

  6. #6
    Advanced Tuner IARLLC's Avatar
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    That is pretty good news. I think it will get us a deal to finally tune the 8 speeds on these rally trucks. Thanks!

  7. #7
    Advanced Tuner IARLLC's Avatar
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    Some guys on different forums could not get the T87 to work in a 2017. I wonder if they were trying to flash them to the 2017 VIN. It sounds like you found one with a similar enough OS to function. I think that I will run a bit of an experiment before buying a few T87. Looks like I will be able to try a 2015.5, 6.2, 8 speed, 4x4 T87 in a 2017 in a few days. If it works I can just buy new T87 from now on. Hopefully these guys will let me run the test. Will let you know what I find out.

  8. #8
    Advanced Tuner IARLLC's Avatar
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    It worked!!!! Today I borrowed a T87 out of a 2015.5 Yukon Denali XL L86 8L90E 4x4 3.23 and stuck it in a 2017 Silverado L86 8L90E 4x4 3.23 that I had previously tuned (PCM only).

    I had expected some king of codes but thought that it might be OK for a race truck......BUT no codes (checked with GM MDI)! Nothing weird at all!
    Shifting was as expected. It might be closer to perfect if calibrated for the numbers on the trans but it is plenty perfect for a race truck that will soon be tuned for smashing through the desert.

    That is the coolest news. I plugged HPTuners into it and even though I had previously tuned the PCM it automatically wanted to do a full read of the PCM and TCM. All good. I put the T87 back into its 2015.5 Yukon for now. Ordering a new T87. When it gets here I will put it into the Yukon, flash it with an MDI on ACDelco TDS then toss it into the Silverado and start the tranny tuning.

  9. #9
    Tuner in Training chameleon's Avatar
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    I looked everywhere but seems no solid info from anyone that has done it, but would a T87A from a matching 10L90E (2018 Escalade) can be swapped into a 2015 Yukon denali T87 with 8L90E ? obviously the T87A has to be unlocked and vin matched but it would seem the wiring should be all the same, but i would like to think it would work swapping in the 10spd with its matching T87A ?

  10. #10
    Advanced Tuner IARLLC's Avatar
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    I just got a little time this morning to consider this more. My answers probably just bring up more questions for your swap. Hopefully it helps though.

    Harness: While the TCM connector is the same for T87 and T87A, also for both 8 speed (whether T87 or T87A) and 10 speed, the harness does not appear to be the same part number. Maybe they have a different connectors on the trans end of the harness. There might be wire differences too but I am on the road so I don't have access to my wire and connector diagrams.

    TCM: I have successfully installed a T87 from 2015.5 8 speed in a 2017. It worked fine without even programming the VIN. I checked it with GM's MDI/GDS, no codes or anything. Later, I purchased a new T87, installed in a 2015.5, programmed it to the 2015.5 then installed it in a 2017 and tuned it there, all 8 speeds. Worked great (even with 2015.5 VIN). When I plugged into it, HPTuners read the T87 instantly (like as if it was still in a 2015.5), directly. I don't know what exactly changes when HPTuners unlocks a T87A. If they remove the locking part that sets it apart from a T87 (except for the ability to run a 10 speed), maybe this would work. BUT I think that reading an unlocked T87A can only be done while connected to the internet as you cannot actually read it, but get a generic "read" via the internet from HPTuners....so even if you install it in a 2015 and it runs, I don't know for sure what you would end up reading when you try to tune it. This depends how HPTuners decides which generic trans tune to give you when you plug it in. If it is via PCM info...you'd get 8 speed info. If HPTuners decides based on the operating system already in the T87A...maybe they would send you a 10 speed "read". One way around that would be to tune it in the 10 speed Escalade that it comes from then install it in your 2015 (probably after unlocking).

    I am really looking forward to hearing how this goes for you. Please keep us up on your progress. If I can help, I will.

  11. #11
    Tuner in Training chameleon's Avatar
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    from i have been able to dig up, the 10speed trans connector is round with flat top and bottom and is 26 pin, the 8speed trans connector is round and 27pins. if you can get me those wiring diagrams that would be great. also need to figure out if a T87A will have no issues communicating with a 2015 ecu.

  12. #12
    Advanced Tuner IARLLC's Avatar
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    That is what it comes down to. I just don't know exactly what HPTuners does to make a T87A "unlocked". I can tell you that 2017 and newer (T87A) HPTuners no longer reads what is in the TCM. When it would normally be reading what is in the TCM it is actually just looking at the OS and giving you a generic trans tune to start with. Even after you modify the tune and load it into the TCM it will still "read" as a stock trans tune. This changed when I installed a T87 in a 2017 Yukon Denali the first time. Even though the vehicle was a 2017 that I had already tuned (PCM only) it now read the TCM and did not require licensing the TCM in order to make changes to it. This makes it appear as though it is the actual T87A that requires the "unlock", the extra TCM license fee, and the need to download a generic TCM stock tune via internet...and not the PCM/year etc. This leads me to your complication.... On a 2015 will it do the opposite? Let's say that you have HPTuners unlock a T87A then you install it with a 10 speed harness and a 10 speed of course... will your HPTuners be able to read the actual TCM? or will the TCM signal HPTuners based on its OS and get you a generic stock 10 speed tune to modify? I kind of expect the second option. That would be OK. I am concerned that your HPTuners system might give you a generic stock 8 speed tune based on its expectations of the vehicle. I really don't know for sure. Probably, Bill can tell you for sure, based on what they are changing when they unlock T87A. I am starting to think that it can work. We'll see.

    I am flying back home in a few days and I can send schematics then.

    Happy New Year!

  13. #13
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    Will an unlocked T87A out of one car, installed into another, be able to be read and allow changes without having to license it again? Or should I get a used T87 to use in the new car? This is a situation I'm fixing to be in.

  14. #14
    Advanced Tuner IARLLC's Avatar
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    Maybe Bill could answer about what exactly the unlocking accomplishes. I know that you will have to license it for sure. From 2017 (T87A) on, the TCM requires its own license in order to make adjustments. Just like a PCM, each tuner has to license each unit (like I cannot tune somebody else's PCM on their license...have to license it myself). That is another reason that 2017 got more expensive.

    2016
    License/tune PCM (E92) and TCM (T87) for $100 total.

    2017
    Unlock and license/tune PCM (E92A) for $200
    Send TCM (T87A) for physical unlock for $200
    License/tune TCM (T87A) for $200

    Of course this is the main reason for this thread.

    The problem with doing this on your swap is that I am pretty sure a T87 does not have everything it takes to run a 10 speed. Hopefully I am wrong about that...would be nice.

  15. #15
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    Quote Originally Posted by 8850 View Post
    Will an unlocked T87A out of one car, installed into another, be able to be read and allow changes without having to license it again? Or should I get a used T87 to use in the new car? This is a situation I'm fixing to be in.
    This is with the T87A already unlocked and licensed. Can I install it in another car and use the same serial number HPT to tune?
    Last edited by 8850; 01-02-2020 at 02:39 PM.

  16. #16
    Advanced Tuner IARLLC's Avatar
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    Iiiiiiii think so. Can't wait to find out. Sometimes things that are forward compatible are not backward compatible...(2017 E92A worked fine with an unmatched 2015.5 T87). As the unlocking of the E92A is worked out over the internet yet the unlocking of the T87A requires something to be done at HPT...I just can't be sure. But I hope so.

  17. #17
    Tuner in Training chameleon's Avatar
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    So now the question is, can an unlocked T87A from 2017/2018 be put in a 2015 and work just like the reverse swap of the 2015 T87 into the 2017/2018..
    Im going to buy a T87A and send it to unlock and put it in my 2015 and if that works then the upgrade to a 10L90 should work as well just as long as i figure out he wiring differences..
    now the other question is there are a shit ton of T87A controllers out there with 4 or 5 different part numbers.. yet they all look exactly the same and are T87A .. what even matters where they come from or software they have loaded if when they get unlocked and Hptuners gives you a generic file for whatever you tell them you have, that would mean that they would all work exactly the same.. right ?

  18. #18
    Tuner in Training chameleon's Avatar
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    Quote Originally Posted by 8850 View Post
    This is with the T87A already unlocked and licensed. Can I install it in another car and use the same serial number HPT to tune?
    yes that will work.. not sure if the T87A are vin locked as well.. so because of a vin mismatch.. it might not allow it? but try putting it in a 2015 and see if it works..

  19. #19
    Advanced Tuner IARLLC's Avatar
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    To be clear, the T87A will need to already have the correct OS for the 10 speed before it is installed in the 2015. Easiest is to get one used that is definitely from a 10 speed with the same gear ratio and all. Back when I did the TCM swap I started out with a used T87 with the same 8 speed and gears and it worked perfectly. Then I bought a new T87 and installed it in the 2017 (which I had previously tuned the PCM) and could not do anything. Using GM's GDS with an MDI I tried to install a 2017 OS while installed in the 2017....GM would not allow it. I tried to install the 2015.5 OS while installed in the 2017...GM would not allow it. Finally I grabbed the same 2015.5 that I had used for the first experiment and installed the new T87, loading a 2015.5 OS, calibration, and valve body information via GM GDS with an MDI. Then I installed the T87 back into the 2017 and it worked fine with no codes. Then finally I was able to read the T87 and tune it. GM says that, at least for 8 speeds, you need all of the info off of the specific valve body written into the TCM when it is installed...They say that there is enough difference from valve body to valve body to cause differences in shift quality. That is why they require that you input the specifics from the valve body that it will be used in. I did not have any such shift issues after I took it through the learning processes. Your best case is to get the TCM from the vehicle that the trans is coming from or to get all of the info from the 10 speed that will be used and the VIN of the vehicle that the 10 speed was taken from and see if HPTuners can unlock and program a new unit fully to be able to work in the original vehicle...then install in your 2015. Still fingers are crossed.

    GM says not to "swap" any Gen 5 modules. Even swapping a Transfer Case Control Module can cause a no-start...but as mentioned, the T87 with VIN and OS from a 2015.5 worked just fine in a 2017.

  20. #20
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    Quote Originally Posted by chameleon View Post
    So now the question is, can an unlocked T87A from 2017/2018 be put in a 2015 and work just like the reverse swap of the 2015 T87 into the 2017/2018..
    Im going to buy a T87A and send it to unlock and put it in my 2015 and if that works then the upgrade to a 10L90 should work as well just as long as i figure out he wiring differences..
    now the other question is there are a shit ton of T87A controllers out there with 4 or 5 different part numbers.. yet they all look exactly the same and are T87A .. what even matters where they come from or software they have loaded if when they get unlocked and Hptuners gives you a generic file for whatever you tell them you have, that would mean that they would all work exactly the same.. right ?
    If you were in the Houston area you could try my unlocked T87A. It is out of my 2017 Z06 Corvette that is 8 speed.