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View Full Version : T76 Transmission / Tuning Swap - I'm stuck!



Josh61513
December 19th, 2012, 04:51 AM
We are working on a unique project in which we have replaced the factory transmission in a 2010 GMC Terrain ("Generation 1" 6T40 with a T76 Controller) with a newer, 2012 6T40 Transmission which is a "Generation 2" with a newer T76 TCM. The "Generation 2" Transmission & TCM was purchased brand new from a dealer, and as such I don't think has a flash of any type. The Gen-2 trans & TCM has been installed into the 2010 vehicle and it doesn't have any forward gears and it give codes which indicate TCM communication issues from transmission "Control Module Not Programmed" in the TCM. I interpret this as the factory not supplying a calibration file of any type to the transmission, expecting that a brand-new transmission & TCM would be flashed by the dealer after installation. I'm not sure if that is an option as this is a newer 6T40 designed for a 2012 vehicle that's installed in a 2010 Terrain.

I've pulled the tun from the Gen-2 TCM now that it has been installed into the vehicle, and the information from it is as follows:

VIN: N/A
Hardware: 24255544
Operating System: 24265790
Calibration: 24265789
BCC: 5789
Transmission Calibration: 24265791
Transmission Diagnostics: 24265792
System: 24265793

Do I need to find a "full flash" for this TCM, or just a calibration file? It appears that EFI-live doesn't support full-flashing of T76 controllers (yet, I hope). I believe it does supporty calibration-only flashes (via V8). I did try to flash a calibration file from a 2012 Terrain but EFi-live give me an error from the operating systems not matching. Any ideas? Would it be possible for a dealership to flash the TCM using a VIN from a 2012 Terrain via a Tech-2? I'm lost right now!

Thanks,
Josh

GMPX
December 19th, 2012, 08:34 AM
All new ECM's or TCM's have what I guess could be called 'no start' programs in them. So yes they need to be flashed with a TechII, all you need to do is tell SPS (GM's programming software) a VIN from a 2012 Terrain and it will flash in the correct tune.