Prnd failure



I have audi A4 3.0 V6 front drive 2002 automatic.
I drived it in really rainy day and after 200km drive the gearbox went to limp mode(?). You can drive if rpm is in 4000 and it slowly goes up to 50km/h for 700m-1km(gears are changing) and then it goes to N (?)

I checked for faults with VCDS and it showed me this;

18226 - Pressure Control Valve 2 (N216): Electrical Malfunction
P1818 - 007 - Short to Ground - Intermittent - MIL ON

I've read that it helps if you change Transmission Control Unit(TCU) which is attached to gearbox(?), but then some say that you need to change Transmission Control Module which is located under the ECU.

And then some say that TCU is under the ECU and TCM is attached to gearbox. I'm really confused.

So which is which?

This happened shortly after that I accelerated to full throttle (overheating?)
I also drove through puddle few times.

Also does 4wd 3.0 tcu fits to front drive 3.0? Where could i get the tcu's serial?