I watched a good video today (1 hr!) on complete disassembly of that; just for learning about it. I hope I never have to go that deep into one. The unit is quite simple to understand except for the "transmission mode actuator". What does that do? There is talk (in the video) about it controlling P/N/D/R operation. It can obviously drop a pawl into place for P, but there is no way the gearing can change; either to disconnect or N or reverse for R. The motor is direct-coupled to the diff with D/N/R all being set by how the motor is driven electrically. Any guesses?