GM Part number for A41

[oxman504]

I'm working on an Allison 6 speed swap behind a 7.3. My wiring harness is built for a 8.1 cal. I went to the dealer to get the brand new A41 flashed, but the tech couldn't get the TCM to take the cal. The A41 was flashed with a 3500rds cal. He was trying to flash it via wireless MDI with OS 24259900 which is for the newer T14A TCM. It would load up all the way to 100% then start back over. It did this three times then failed. I looked at the cal in EFI and got error messages that it was the wrong cal for the TCM, but all of the tables are the same shift points as an 8.1 cal. I tried to drive it, but it was just in limp mode as if there was no TCM hooked up. I also tried to data log and couldn't even set up pids or even scan for DTCS. The things I can think of is A) They should be using a USB cord instead of wireless, B) They should only have the TCM hooked up and not the BCM, C) The 24259900 OS is not backwards compatible with A41, D) We need the right 8.1 OS for an A41. So I'm looking for anyone that knows either the GM A41 part # or a way around this.

The tech manually put the part number of 24256864 which is on the back of this T14A.

http://i1088.photobucket.com/albums/i331/oxman504/Mobile%20Uploads/20606_zpsjaepdd2x.jpeg (http://s1088.photobucket.com/user/oxman504/media/Mobile%20Uploads/20606_zpsjaepdd2x.jpeg.html)


This is the TCM that I'm using. We tried looking for all the numbers on the back of this one in MDI and no luck.

http://i1088.photobucket.com/albums/i331/oxman504/Mobile%20Uploads/20899_zpsznkz5xnw.jpeg (http://s1088.photobucket.com/user/oxman504/media/Mobile%20Uploads/20899_zpsznkz5xnw.jpeg.html)


Any help with tis would be greatly appreciated.

[oxman504]

I say we tried all the numbers on the back of the A41. I wasn't right there when he was putting the numbers in so I don't know which numbers he tried. From doing some research it looks like the number we should be looking for is 29544773.

[oxman504]

GMPX, THEFERMANATOR, DURAtotheMAX, any other Allison guru?

[GMPX]

GMPX...........any other Allison guru?
I'm not in that group to begin with :angel_innocent:

[oxman504]

Well maybe not, but you are pretty well versed in these types of things no?

[GMPX]

Officially EFILive only supports the A40 and A50, there seems to be a number of 'close to them' Allison TCM's out there, unfortunately we don't have any of these in house for testing. Given that I've never looked in to the internal structures of the A41, T14 and whatever else is out there in the same case. So on those two variants I'm sorry I don't know much about them. The other guys you mentioned probably know a lot more but given it is the weekend they might be too busy to respond.

[oxman504]

I know that you can tune with EFI live for all of the A40 and A50 variants also the T14A which is the replacement for the A40s and the T14 which is the replacement for the A50s. The question is what part number do I use for an A41 when flashing with GMs MDI.

[GMPX]

The question is what part number do I use for an A41 when flashing with GMs MDI.
I don't know, one of the other guys you mentioned might have done it before to know.

[oxman504]

Well I'm at the dealer right now ANY insight would help right now. I don't have great faith in the tech that is doing it.

[oxman504]

Found out that if the TCM has been flashed with a Medium Duty cal you can't flash a GM cal over it. That sucks. Anybody looking for 2 brand new medium duty A41 TCMs?

[RADustin]

Go see an Allison dealer and get it done. no?

[oxman504]

Got it done already. Got an T1A4 TCM from GM for $260 and had Mike at Doug's Auto in Wisconsin flash it and the BCM for us. Allison DOC can't flash a GM cal. It's for medium duty only.

[schwoch1]

Got it done already. Got an T1A4 TCM from GM for $260 and had Mike at Doug's Auto in Wisconsin flash it and the BCM for us. Allison DOC can't flash a GM cal. It's for medium duty only.

Glad to hear it all worked out. It actually was quite simple :)

Mike