working on a XJ cherokee with a 08 5.3L 6L80E, dont know what year is the trans, i tried to load the stock tune and it say that it had a invalid calibration, i still read it, but didnt have VIN number and it looks like the tune was broken or something, so i took the OS (24239353) searched for a T43 stock tune on tunefiledepot and tried to do a FULLFLASH with the new base stock tune and when finish it says: code $06FF: checksum failure

Any help? i dont want to swap the TCm,trans already has OIL