@ Paulwidnes1, maybe what I did will help you out.
So as I had a bit of spare time today I decided to tackle the job and see if I could get at any of the wiring. Having established that there was in fact power coming through wires to the reversing/fog/rear light, I was a bit stumped as to what the problem might be, as the lights would not work. Then it hit me, the earthing was not working. Therefore there must have been a break in the earth cable (the black one on the far right of the connection block). So, after getting the plastic covered assembly out from the top corner, I stripped the covering back to reaveal the wires and found that there were 3 severed black cables! WTF? One was the earth for the lighting block, one was the power for the rear demister (I had thought it was not working but wasn't sure), and one was a co-axial cable that seemed not to connect to anything except end in a blank connector behind the trim at the top of the hatch. I therefore found some spare electrical cable, a few connectors, and spliced the cables back together. All seems to be working now, so I am pleased with saving a hefty sum at the dealers. I might take the plunge and get a new wiring harness block to replace all of those wires over the summer.
On a side note, taking 3 hours to do this, turning the lights on and off, leaving them on for a while etc, drained my already weak battery! Luckily I have a new smart charger after our cold winter also drained the battery!
onder:
