If you can't communicate with the TCM with your scan tool there is certainly some sort of issue. Can't really say if the issue(s) is related to faulty wiring between the transmission and the TCM, or a damaged TCM caused by previously damaged/shorted wires.

What kind of scan tool are you using?

I don't think a faulty lateral acceleration sensor will cause the transmission to go into limp-home mode but I do know that if a 722.6 enters limp-home mode with certain stored fault codes it will NOT reset itself after the condition that caused the limp-home mode is corrected.

To get it out of limp-home mode you must erase the codes and reset the transmission using SDS or another appropriate scan tool. If you can't communicate with the TCM this is going to be a bit problematic.

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