Outer Limits 4x4 Board

Right then chaps,
I own a 91 200Tdi Discovery and when I checked the lights, I found I have no rear fog lights working! Fuses ok, bulbs ok and power getting to the switch but no power getting to the rear light cluster. Is there another break point between the switch and the rear lights? Before I start stripping the dash down to find the wire, has anyone had this problem before???? Also does anyone know where the wire is routed to get to the back of the vehicle.
Cheers guys.

Are you checking them when your headlights are on?
They only work when you have your headlights on, eg. you can't leave them on and walk away without having the headlights on as opposed to other european cars.

Yep, headlights are on and engine running. power is going from the switch but isn't reaching the rear light cluster.

Just spent the morning stripping down the dash to check the wires for the rear fog lights but still no joy. Haynes manual not really much help.
Does anyone know if there is a relay for the rear fogs and if so where is it?

I've ran a wire direct from the battery to the fog light wire hidden behind the windscreen pillar and that gives me rear fog lights so the rear light cluster is fine.

Any ideas please???? (Yes the lights are on when tryng rear fogs)