Problem with the Can Fiat Siena 2005 system

Hello everyone, I am new on the page and in the forum, I am a mechanic, and I have a problem with the SIENA 2005 SIENA system with Bosch Motronic Me 7.96F injection.
I set the co -light on the board, I put the scanner and it gives me that the Can system is lacking. Some of this happened to someone ???. Because I have enough technical material but I can't get something to know what each cable contains, if current, dough or signal. Well I hope to find some light that guides me, hahahajaj.