I have a 1984 240 GLE estate. The rear fogs aren't working. The fuse is OK, the switch lights up and the bulbs aren't blown. Anybody any ideas what it might be or what to test? Thanks

I think first thing is to volt meter test at the bulb terminals, guessing there will be nowt! Then follow the wires back & see what you find? Good Luck

Thanks for that. Yes I have got a towbar. Where is the switch in the socket? Any idea on cost?

Is this something 'new' and specific to 2-series? I have had tow bars fitted to 2s, 7s and 9s and never had any fog light operation problems.

200 series rear fogs 

I have changed a number of these over the years due to corrision in the socket, it quite a common problem, I think the idea behind the switch in the socket in the first place was to save having the rear fogs on the car and the trailer/caravan at the same time, the switch isolates the fogs on the car once the towing plug is plugged in, there is no need to have rear fogs on the car if the caravan hides them, and you don't get the glare reflected back from the caravan either, and there is less load on the wiring.