Originally Posted by
prlsa
I am in the process of finishing up my car tuning but I am having an issue with the TCM. I bought a new TCM from HP Tuners already unlocked and ready for tuning but once I connect it and do the TCM replacement process on HP Tuners, it quickly throws a code of P0700. I tested it and downshifting from 3-1 is hard as well as putting it in reverse. I installed back the original TCM and the code went away and transmission started shifting correctly. Is there a process I'm missing? Is the TCM faulty?