if you've checked the obvious fuses connections etc, then simplest thing to do is take a wire from position 2 of the ignition switch itself where it outputs to lecky in pos 2, take this live to speed switch, all else being ok will then work.
The supply for the front fogs on my sapphy disapeared so I just branched over to the rear fog switch supply, just not worth ripping the car to bits to find the broken wire/connection.
tabetha