In my search for what triggers the input sensor I found these ZF manuals. See thread for details of my problem to date L322 Trans failsafe message and fuse 54

Manuals are pdf to be found here:-

ZF 5HP24 1 Repair Manual.pdf

ZF 5HP24 transmission parts manual.pdf

I also found on a BMW site this file on electronic transmission control.
http://www.ge39.com/files/electran1%2B2.pdf

Hope these are of some use as I haven't seen them on here before.