LMM Transmission Issues

[rfletes79]

That’s funny..... I clearly remember purchasing a new acdelco a40 tcm from rockauto..... it not being programmed (just like it advertised) and having the dealer do the install and flash. Oh and also attempted to do a full flash with my flashscan.

This is true.....

 

[Ne-max]

A40s are different then a50s

 

[$chultz38]

A40s are different then a50s

Yep but LMM had both and I thought that someone put a 50 into a 40 and ran it programed it as a 50

 

[JDT4430]

Well the A40 is working. The bad thing is it was kind of cooler here today and mine never messed up today which i was hoping it would so thay away i would know as soon as i put it in that it was for sure the issue but I will just run it for a few days before buying a new one.

 

[Harbin_22]

Both must have been A50s then?
I think 50s go into 40s but not the other way maybe?

Nope. LMM A50 and A40 can be swapped either direction. Mine was an A50 ,not tunable at the time, put into an 07.5. The 07.5 A40 was put in my truck to tune it. Both ran fine with zero issues

They were not flashed over, obviously couldn't flash the A50 at the time, and worked fine. My 2010 CCSB truck has TCS/Stab and the truck it went was a dually without any of it.

 

[$chultz38]

Nope. LMM A50 and A40 can be swapped either direction. Mine was an A50 ,not tunable at the time, put into an 07.5. The 07.5 A40 was put in my truck to tune it. Both ran fine with zero issues

They were not flashed over, obviously couldn't flash the A50 at the time, and worked fine. My 2010 CCSB truck has TCS/Stab and the truck it went was a dually without any of it.

Thanks for the info! I do know that a A40 will not work in a LML but a newer A50 lmm will and will not have the reduced main line psi strategy programing.

 

[JDT4430]

Truck is still shifting and acting right with the A40 TCM so I'm confident enough that the TCM is my problem so I'm going to order a new one. My question now is can or is the EFI V2 capable of pulling the data from the old TCM and flashing the new one to avoid having to go to the dealer? Also do the T14 24256861 and the A50 25978353 cross. The one I found on amazon shows to replace either of the two but don't want to find out the hard way that it wont work.

 

[duramaxnate]

When you get a new "A50" from GM or any supplier they ship out a "T14". Which has a different base binary file than the "A50" that was installed at the truck from the factory. I have tried flashing new ones with my v2 and have failed. When I use my MDI2 to gain access to GM's TIS2WEB and flash it with the newest file for the VIN it works great. Ask Mike L. I have done a couple at his shop.

 

[Ne-max]

Interesting. My brothers a50 on his LML just took a crap. Got a new one from Amazon. Pulled his stock file. Installed new one. Loaded it right up with my v2. I also had Tony send me a custom file a while back and it loaded fine on a new tcm. That one was 100% shot where I could not recover it.

 

[JDT4430]

A40- '06 LLY/LBZ and early LMM
A50- late LMM and LML

Great info here on this-

https://forum.efilive.com/showthread.php?27672-Allison-6spd-TCM-versions

Just went back and renread this and it makes a little more sence now. so if im reading it right acording to that post if i try to flash a T-14 with the A50 OS it will brick it and then i will have a $275 paper weight to go along with my origanal one. (The only thing im not sure of is what they mean by SPS and MD, i think MD is medium duty but not sure, can someone ease clear this up for me.)

With that being said I think I might just order the new one on amazon that comes pre flashed to match my VIN. Has anyone gone this route and if so how was your experiance.

Again I would like to thank everyone for their help!

 

[JDT4430]

Just wanted to give an update. I bought a TCM on amazon from FlashMasters, I sent them my vin# and they flashed it before they sent it to me. What I received appears to be a brand new AC Delco TCM. I installed it and has worked great and fixed my issues.

Thanks again to everyone that helped me get to the bottom of the problem.