Hello,
Autoscan? Then you can see what components are installed and how they are configured.
It's best to base it on comparable vehicles, e.g.
https://community.dieselschrauber.org/en/viewtopic.php?t=30509
In the gateway (control unit address 19), it is important to activate the trailer control unit (69) in the parts list, code the engine control unit, and then check what is installed and what still needs to be adjusted.
Best regards, Rainer.