8 Speed T87 compatibility

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October 2nd, 2018
LS-SWAPPER

8 Speed T87 compatibility

Ok, I've done some research, some googling, and some forum searching, I'm left with more questions than answers.

We are dealing with a 2017 L83 engine, 8L90e trans, e92 ecm, and T87 tcm. The drivetrain was put into a restored k5 blazer. The engine starts up and runs fine. Once put into gear though it has no forward gears, only reverse. After some research we found this article...

https://gearsmagazine.com/magazine/8...id-strategies/

Specifically this quote:

"If you change the transmission, valve body, solenoids, or TCM during a repair, you must download the unique performance characteristic data from the web server and reprogram the TCM for the system to function at maximum efficiency"

A new GM TCM was purchased for this project because the salvage yard didn't include the original one. So everything came from the same truck, EXCEPT the TCM, it is brand new. The engine and trans had under 1000 miles when the truck was wrecked so physical components are in good shape, basically new from the factory.

My question is this, can EFILive take care of this "unique performance characteristic" change? The blazer and me are no longer in the same state, so we were hoping to do this through the mail. Would I need the TCM and ECM in front of me I guess? Any insight to this is appreciated. Sorry if this is a dumb question, been reading up all night with limited success. If there is a link or something someone can share that would be great. THANKS!
October 2nd, 2018
GMPX

No EFILive can't do that, but I'm not 100% what the process involves actually. I'd say that GM's systems probably program in some default values for the TCM to learn for a given trans type.
I wonder if you might be better off trying to find another one pulled from a similar vehicle and use that instead.
Also just thinking back to the six speed, I think they did some specific checks before the learn procedures would initiate, checks that usually meant it had to be in a GM vehicle (things like brake switch etc).
October 2nd, 2018
LS-SWAPPER

Oh...I was not expecting to hear that it couldn't be done. I was expecting to hear it was complicated, but not that it couldn't be done. I am being told by another shop that they've done it with "the competition" but I'm just going off verbal conversation.

GMPX, I trust what you say, if you say EFIlive cannot do this procedure then I will take it to be true. I'll tell the customer to look elsewhere, perhaps they can get a buddy at a dealership to do it... after hours sort of thing. Thanks.
October 3rd, 2018
joecar

Quote:

Originally Posted by LS-SWAPPER

...
The drivetrain was put into a restored k5 blazer. The engine starts up and runs fine. Once put into gear though it has no forward gears, only reverse.
...

There are other problems here, either electrical or hydraulic.
October 3rd, 2018
LS-SWAPPER

Could be, and I plan to tackle that, but isn't this "pairing" an issue regardless?
October 3rd, 2018
GMPX

Quote:

Originally Posted by LS-SWAPPER

Oh...I was not expecting to hear that it couldn't be done. I was expecting to hear it was complicated, but not that it couldn't be done. I am being told by another shop that they've done it with "the competition" but I'm just going off verbal conversation.

GMPX, I trust what you say, if you say EFIlive cannot do this procedure then I will take it to be true. I'll tell the customer to look elsewhere, perhaps they can get a buddy at a dealership to do it... after hours sort of thing. Thanks.

Well as I said originally "I'm not 100% what the process involves". If the other shop can tell you how simple or complicated the process was then at least we'd all know what is involved. However you did mention that you'd like to do it 'through the mail'. I can't see how that could possibly happen because the TCM would need to learn the characteristics of the trans itself whilst hooked on to the trans.
Who knows it might be as simple as initiating the fast learn mode like we can do on the T43 in V7's DVT controls. FWIW, GM do not sell a car where EFILive is based with the 8 speed auto, makes it a bit hard to test things.
October 3rd, 2018
GMTECH4

There is a unique number on the side of the transmission called the transmission unique number "TUN" that must be programed into the tcm. that same number is on the valve body which is called the part unique number "PUN". you can not copy this number from anther vehicle it contains flow rate data for all the pressure control solenoids inside valve body. GM flow tests every solenoid inside trans to come up with these numbers none of them flow the same. the TUN number will be the same on the valve body unless valve body has been changed at some point. I would remove the valve body and double check they match. always use the number on the valve body. YOU WILL BURN IT UP WITH WRONG DATA. when you program this data in tcm make sure you do a fast learn and use dextron hp fluid. any gm dealer should be able to this with the vin that came with drivetrain
October 3rd, 2018
LS-SWAPPER

Nice^. Thanks for the info. We built this harness, had the ECM and tcm in hand. Ran everything on the run stand, then sent it to the customer. We were not aware of the TCM being this sensitive at the time (a few months have gone by, learned a lot).

GMTECH, so have you looked at doing entering this data via EFILive, or is your experience with GM diagnostics?
October 4th, 2018
GMTECH4

mainly gm diagnostics, if you post the tcm tune I can look thru it. I only tune my personal stuff. if you anywhere in the atlanta, Georgia area I could help you out
July 24th, 2019
Chuck CoW

Quote:

Originally Posted by GMTECH4

There is a unique number on the side of the transmission called the transmission unique number "TUN" that must be programed into the tcm. that same number is on the valve body which is called the part unique number "PUN". you can not copy this number from anther vehicle it contains flow rate data for all the pressure control solenoids inside valve body. GM flow tests every solenoid inside trans to come up with these numbers none of them flow the same. the TUN number will be the same on the valve body unless valve body has been changed at some point. I would remove the valve body and double check they match. always use the number on the valve body. YOU WILL BURN IT UP WITH WRONG DATA. when you program this data in tcm make sure you do a fast learn and use dextron hp fluid. any gm dealer should be able to this with the vin that came with drivetrain

You're not necessarily programming the TUN or PUN into the trans.... What's happening here is much different than getting around the old "stolen radio" scenario where you use a tech 2 to copy the vin # into the radio and it unlocks it.

In short, when the trans solenoids (which are unique to each vehicle) are manufactured there is a data file created and that data file is posted on TIS via the Vin # if the trans is totally "AS BUILT" or if the VB or solenoids are

replaced, then you need the TUN or PUN to identify the new parts and when logged into TIS, you feed TIS the correct ids and then it downloads the new "solenoid characterization" data from the site and loads it

into the trans..... It's VERY unlikely that a trans will operate correctly if those values are not programmed correctly.

Chuck CoW