Schema Car-Radio Xsara 2004, What to keep and what not?

How can I get the schematics of this radio? (rds radio cd player, display on dashboard)
I did build a new cheap radio with sd-card and usb input, but now is a part
of the information gone (fuel per 100 km , km to go, km and som other things when you push the clignoteur biutton)
I could place back the concerning parts, but what is neccesary and what not? I modified more often radio's and televisions, so I am not a beginner.
Getting a 2nd hand original radio is not an option, I want the functionality of sdcard and usb input.
Greetings and thanks

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