I assume that you want to know so that you can either switch between cameras?
I have had rear-view/reversing cameras fitted to several vans and soon come to the conclusion that switching this way didn't give the best result.
Because with a 2 camera system it is often better to see with the rear-view camera until getting very close and then switch to the reversing camera.
Perhaps I am wrong and you only have a single camera?
Hi David. I only have one camera, I wanted to energise the camera and monitor from the rear light. Some link the monitor to the fuse box and if this doesn’t work I will do that. I did as Gary suggested and it was the thicker white/green wire. I have done the back end (temporarily) and will do the monitor in the morning, if it works (no one will be more surprised than me!) I will solder all joints. Thanks for replying all advice is appreciated.
Just a word of caution: The rear lights are all fed from a controller on the CAN bus. This is how they can indicate that a bulb has blown, it also means that additional loads on any of the wires may also trigger a warning on the dash board and an error to be logged in the ody computer..
Incidentally that's why if you have a towbar fitted you cant just wire up the trailer socket by splicing into the rear loom.
This is an official wiring extension, very expensive there are cheaper variants on ebay but not sure how good they are.
Thanks again Chris. I did splice into the loom, and it hasn’t as yet indicated an error/alarm message on the dash. A good friend is an auto electrician and I will ask him to check everything for me before I start insulation. John