Damn lol I'm assuming you use this thing everyday and cant ship it to me for a day?Originally Posted by 8850
I found a T87A on ebay for $20 shipped just to experiment with and get unlocked.. but I really assumed once unlocked anything could be loaded on it. So unfortunately it's not even from a 8SPD or 10, but was the same needed service # and approved part # as what would be sold new..
Yea, got to have mine but were you local, giving it a try wouldn't be a problem. The one you found for $20 will most likely have to be loaded with the dealer programming and then sent to HPT to have unlocked. You pay shipping both ways and then have to use 4 credits to tune. Mine has all that done! I think you would have to use 4 credits though unless you had my HPT. And I need it too almost every day. I do have a T87 that I plan to use in my car if it works and the T87A in my new car. I would have some time between the two cars that I could send to you if you haven't found a T87A by then.
Turns out the T87A I got came from a 2017 CTS V with a 8SPd.. lol confidence didnt even pay attention what it was out of.. but end goal is to get the matching T87A out of whatever 10spd I get so that way all the solenoid data is there and least headache possible..
Yea I'm aware of all the costs and credits.. my biggest concern is upgrading to a 10spd which no one has yet done.. it's getting past the TCM and some wiring at the transmission plug.
The obstacles are small yet a pain in the ass!
well this kind of makes no sense, so if HPTuners sells me a brand new unlocked unit, then it would seem they load whatever you tell them your going to use it for.. correct ? so assuming i provide them a used one, they can overwrite it with whatever you tell them you need, if not this should all be stated in a FAQ or something as all these details with how complex this damn T87A is should be posted up so we understand what we can and cannot do.
I understand what you are saying. What you are saying seems logical but HPTuners is trying to make a very complex situation work OK for people that don't have factory GM tools or a swap situation. If you own a 2017, 10 speed and you order an unlocked TCM from HPTuners, they have designed a method for installing the new TCM into your factory vehicle. I think that their method uses your interface to force the TCM to acquire solenoid info from the original 8 speed trans in the original vehicle. This is why I have taken the time to write up the process that I had to go through. When I installed the T87 into the non-original vehicle I was not able to program solenoid data with GM tools...presumably because the GM tools where looking for a match between VIN, year, type of module or something like that.
2 possible reasons:
1. GM tool does not have any way to program the solenoid data except in a situation where the VIN, year, and module type are coordinated and confirmed by the tools. If this is all...maybe the HPTuners interface module installation/set-up will be enough to make it work. I don't know. I hope so but I don't have any experience doing it that way yet and I have read where several intellegent people struggled with their more basic (original trans) installations of unlocked HPTuner T87A...so it seems reasonable to expect more problems when trying to do this in a non-original application.
2. Or maybe, the key is, (maybe, hopefully) the T87A becomes more user friendly in their unlock and can be forced to accept solenoid info via HPTuners interface even though a simpler T87 could not receive solenoid data in a non-original application via factory GM tools.
HPTuners has done a lot to make it possible to tune the T87A in an original application. They have succeeded in that very complicated task. All of the information that you would need for that is available on their site but they have not suggested that they can make it work in a non-original application like this. That is why I have shared the details and possible complications that (I think) I understand.
It still seems to me that your best bet is (like you mentioned) get the T87A along with the 10 speed it already works with then have it unlocked by HPTuners.
or
Get a different (new or used) T87A programmed in a 2017 10 speed application complete with your solenoid data then send it to HPTuners for unlocking and try the swap.
There is still some doubt in my mind about being able to tune it. This depends how HPTuners' servers "reads" your TCM once it is actually installed. As I mentioned before, I was not totally sure that HPTuners would actually read my T87 once installed in a 2017 but it did. If my 2017 application would have had an unlocked T87A I don't think that it would have done an actual "read". From what we read on here, HPTuners would have just loaded a generic trans file during my "read" which would have been OK, as if it would have been based on the TCM OS or the VIN it would have loaded a functional 8 speed file. Here is the next crux of your situation...Since your T87A will probably get a generic trans file from HPTuners during your "read", if HPTuners automatically sends this file based (ONLY) on the OS that has already been properly loaded into the TCM, you should be able to adjust until your heart is content...but if HPTuners' servers read a 2015 VIN and "logic" that it has to be an 8 speed T87, then maybe it just does not send you a file at all... Again, I hope it will just read your properly configured T87A and give you a useful 10 speed file.
Still the way around this would be to make adjustments to the T87A while still in an all original 10 speed vehicle with the same gears and config then just install the TCM into your rig. You would not be able to refine for minor differences in solenoid tolerances but I have not seen those play as big a role on 8 and 10 speeds as GM suggests. As far as I have seen so far the trick with 8 and 10 speeds weird behaviors is to take them through the proper learning functions and give them long smooth coast downs with no braking from time to time.
Not trying to make this any harder than it is. Just trying to flesh out possible unknowns based on the little that I have seen or read. I hope that it works out well for you and we can all learn new options for future fun.
Thank you for the detailed reply.. now it seems every 10spd I find does not have the matching TCM.. they always split them up and not keep them matched so that's going to be the other challenge.. i have a buddy with a supercharged 18 Escalade that will be unlocking his T87A soon.. so I'm going to have to try a few things and get this ball rolling..
The T87 does not work in my 2017 Z06 Corvette. Stays in 4th gear with check engine light on. Will clear but comes right back on when I shift into gear.
What was that T87 from? There are any number of reasons for it to do that. If its OS is for an LT1 Vette or a totally different platform this is to be expected. It will help quite a bit if you can read the codes that it set. If it were just because of it being a T87 I think that it would set codes as soon as you switch the ignition on.
Don't know what vehicle it was out of other than the part number matches a 2016 Z06 Corvette. Bought it used on Ebay and all it said was Cadillac, Camaro and Corvette in the description. The SES light did come on immediately but if I remember right when shifted into gear. Sorry but did not read the code other than it had Transmission listed. It's already back out of the car.
Last edited by 8850; 01-05-2020 at 05:29 AM.
So this TCM could be from a 2.0T Camaro, or a 3.6 anything, 5.3 Tahoe, etc. Good thing it set codes. There is no way that it would have commanded enough pressure to handle your LT4.
Within the programming of a T87 are 6 different GM programs with actual part numbers that have to be correct for your application. Each has its own function. When we adjust the calibration via HPTuners I think that we only touch one of those. There are differences between all platforms. If I remember correctly the Corvette TCM program takes direct input from the paddles while all other GMs send tap/up/down via BCM...thus the delays we don't like when manually shifting all of the others. When I installed a T87 in place of a T87A I was working on Yukons, Silverados, and Sierras with the same L86, 8L90E, A4WD NQH t-case, 3.23 gears, etc, etc.
just figured I share a snippet from the T87A unlock page.. which confirms that you can give them Any T87A and they will program it for whatever you are going to use it for.. I asked via email so waiting on that confirmation.
"TCM Unlock & Program Service
You can now send us your T87A TCM (new or old) and we will pre-program it for your specific VIN so its ready to plug in and you can start tuning immediately, no need for the GM factory tool. Simply select “Unlock & Program” from the dropdown box above and ensure you include your VIN. Note, if you are removing the T87A TCM from your vehicle and plan to reinstall it in the same vehicle, you do not require this service."
https://www.hptuners.com/product/tcm-unlock-service/
Hey you happen to have wiring diagram from the 8L90 & 10L90 trans plug ? im already going to assume the wiring at the T87 & T87A plug is exactly the same since they can be swapped.. but the trans have different connectors which i should be able to make my own adapter harness being that the number of wires are the same and i should be able to make it work via rewiring the plug once i get past the T87A working..
To this I will still say that HPTuners are offering this for OE situations, not swaps that cross unintended lines. It seems to me like it will probably work as long as they set up the TCM for the VIN of the vehicle that the 10 speed came out of.
It kind of depends when the solenoid info goes into the TCM. If via VIN (of trans donor) HPTuners is able to apply appropriate solenoid info before they ship it back to you then it won't be needed during installation. HPTuners might apply some kind of generic solenoid info that works well enough but it seems unlikely they could have it via VIN. Still this is the second best scenario (behind getting the actual T87A that GM originally matched to the trans).
If the solenoid info is not there yet and is acquired/applied during installation, HPTuners will have added a process whereby the info is written at the time of installation. Since this would have to be a somewhat automated process it would have to depend on info that HPTuners can read from your vehicle. GM tools read a conflict if the T87 is in a 2017 or newer T87A vehicle (as previously noted). If HPTuners only cares about what it reads from the TCM during this automated process then it should go smoothly.
I bring these things up because I just don't know how HPTuners has arranged this process. I hope that it all goes very smoothly.
With regards to the wiring diagrams, I have been on the road/in the air for over 7 weeks...just landed back home. I will dig up the diagrams asap and post them here.
Last edited by IARLLC; 01-06-2020 at 04:07 AM.
I know this is father down the road but what are you going to do about the dash showing 6 or 8 gears if you now have a 2 or 4 more gears??
Have no idea lol .. it never shows up unless im in Manual which I never am.. and if i am its just to blast thru 1-4 or so.. hoping since it was digital it would just work but honestly that would be my least concern..
Alright guys, so boatload of info coming right now lol
I got my $21 ebay T87A today, which came out of a 2017 CTSV 8spd.. popped it in my 2015 Yukon 8spd, turned it on.. went into reverse out of the shop, drove around the block, shifted a bunch of gears.. felt funky because it would flare the crap out of all gears if i did any more than 30% throttle, if i didnt it would shift very softly but it drove just fine.. no lights and no codes.. I didnt expect it to work at all because of the VIN mismatch.. but it worked perfect. If i had a T87A out of a Yukon 8psd im sure it would have driven just fine.. Also got an email back from swaptime who i asked some questions regarding this whole tranny mismatch and definitely seems like good news paired with this T87A working just fine without even being unlocked and diff vin..
T87 vs T87A.jpgT87A Read.jpgT87 Read.jpgSwaptime.jpg
Good news! Thanks! This confirms that the E92 works OK with the T87A. I am guessing that it would still give a code for improper gear ratio if you drove enough in any specific gear for it to lock up etc. But no big deal once it is unlocked and has correct OS, etc for your gears and appropriate shift cals. This looks hopeful for the 10 speed swap.
As the VIN did not cause an issue doing T87 in a 2017, I did not expect the VIN would cause an issue going the other direction. I will dig through some GM factory files today but I don't think that the TCM even knows the VIN, more a matter of it having the correct calibration for rear gears, each gear, weight, torque, solenoids, etc.
On the VIN issue, I expect it will be best to give HPTuners the VIN of the donor Cadillac (10 speed). With your VIN, you would more than likely end up with 8 speed programs installed.
Do you plan to keep it? I would like to try it in my 2017 Z06 Corvette. Send me a price shipped to 77479.
Last edited by 8850; 01-07-2020 at 11:53 AM.
18, 8 or 10 speed TCM.png18, 8 or 10 speed TCM details 1.png18, 8 or 10 speed TCM details 2.png18, 8 or 10 speed TCM details 3.png
I finally dug up pin-outs for 2018 Yukon T87A. The details actually show both 8 speed and 10 speed wire colors at the TCM.
Last edited by IARLLC; 01-08-2020 at 02:11 PM.
So awesome! thank you!! so your basically saying its all the same shit...
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