Question

I have disconnected the wiring from under our adria 1993 caravan, the wire that plugs it to the car. We got new cable and got an electrician to put the new 12n plug on. Now none of the lights work (brake, indicators etc.)Don't know what to do followed the colour coded wires under the caravan.

Answer

You probably have an 'earthing' problem. Make sure that your lights are properly earthed.