Just as quickie today, I had fitted a rearview/reverse camera built into the rear high stop light unit and a clipped on monitor to the rear view mirror ( Which I had to purchase separately).
I'd picked up both the monitor and the camera power from a random electrical block hanging around by the o/s rear light unit, it wasn't being used and I have no idea what would have powered had it been plugged in, but I'd tested it out and it only became live with the ignition switched on and or with the engine running. All seemed OK till I took the van out to buy some more ply at which time I noticed that there was significant ghosting happening on the monitor, Hmmmm.
I then unsoldered all my previous connections to this block and powered the camera and monitor strait to the liesure battery, and all was well with the quality of the picture with just the ignition on and with the engine running. I had initially when setting it up connected straight to the o/s rear light and had the same ghosting problem. The supplier of the camera had when I'd phoned him about another problem suggested that there is a problem of interference on the monitor when fitted to Ducatos/Boxers and Relays, so when I'd put it straight to the liesure battery and all was well, I realised that I'd have to use a relay so that ignition live on this block only triggered the liesure battery cct for the camera and monitor which then became a totally independent power supply from the vehicle power system and sorted the ghosting problem. Before I finally tightened everything down I made sure that the relay being triggered from this random ignition live, did not effect the Canbus.
Just fitting this rear view/ Reverse camera has taken a good 4 or 5 hours due to this problem.
I've fitted atleast four of these to Relays boxers and Ducatos and never come upon this difficulty but then this is the first 2017 Sevel van that I've converted all the others were 2016, 2014 and 2005 models so I can only assume that the Cambus electronics are slightly different on later models. So if you get this ghosting problem or bad interference, then you would have to use a relay triggered by ignition live. Phil.