I'm probably going to try and help a local Alli tech out with his personal truck. He has a Dodge/Cummins with a 6 speed Allison behind it. He's been trying different Allison Calibrations, and has found one that seems to work, EXCEPT when he puts it into 4Lo. The TCM then limps because the 4Lo ratio isn't what it's expecting, and Allison won't give him a calibration with the right ratio because it's "GM Proprietary". Will I be able to read a non-GM 4th Gen TCM (A40 or A50) that uses J1939 for programming or will EFILive go TILT, OR will a TCM that uses J1939 also accept read/write requests via the GMLAN pins?
The 3rd Gens where easy; they all got programmed over the J1850 bus. 4th Gen not so much...