Rear fog lights not working

Hi,
The MOT is due on my 98 300 tdi and I have a strange electrical problem to sort out. The rear fog lights do not come on when the switch on the dash is pressed but do come on when any door is opened even if dash switch removed!
I have replaced the relay and changed the MFU with second hand one from scrap yard but still the same.
Anyone have any ideas??

Cheers

'Strange' electrical problems are usually associated with a bad earth somewhere.

Remove the lamps and clean up their connectors, ensure the earth lead is to a clean and secure point on the body/chassis.

Good luck

Thanks lookskyward1, I will check all the earths again this weekend.
Cheers