To quote HRH " That wiring looks as though it was done by an I....an"!!! That is terrible wiring if it's original, I some how doubt that it is original as it should be in a flexible conduit for a start, It is most certainly not a Fiat loom anyway. I know in my Rapido the wiring is a total mess and it's original, or at least it was until I got to it to try and put some logic into it. I had 3 red wires running the length of the van with no ID on any of them, a lot of the wiring is ordinary domestic cabling as well, could not find any wiring diagram anywhere either. The best bet is to open the door itself and renew all the wiring from the lock right through to where it joins the rest of the locking circuit inside the van.