The reversing lights & read fog lights stopped working on the tailgate of my late model Peugeot 405 Estate. I'd also noticed that the rear fog light tell tale would light when in reverse.
I wasn't surprised to find that the earth wires on those lights in the tailgate were floating - that is not connected to earth but only to each other.
I have made a temporary fix, connecting the lighting earths to the tailgate chassis - but I'm note sure the tailgate has perfect continuity to the rest of the chassis. Without that my lights may be earthing through some other connection & could just overload it.
Anyway, my guess is that the earth for those lights has come disconnected at the other end of the wiring harness. Does anyone know where that connection is though, under the steering wheel?
Regards