Disco Light switching glitch

Ok - when I used to switch on my hi-beams - the front fog lamps automatically came on with them - now they won't! However, if I dip the hi-beams down to lo-beam (regular) and hit the fog-lamp switch on the dashboard - guess what - the fog lamps come on (and switch lights up appropriately) - then switch back to hi-beam and the fog-lamps go out and the switch, even though still depressed on, will not light up?

Is this some sort of Lucas voodoo?

Is the switch control wand on the steering column on the Fritz or what?

could be the switch or more likely the relay.

On most cars that I've come across the foglamps will only work with the dipped beam so I would think they are working correctly now . I presume it's because you wouldn't use main beam in fog anyway .
As far as I know this is the case with my 96 300 Tdi - will check tomorrow and let you know.