My Fiesta MK4's dipped beam lights dont work. Why? Side & high beam do?

Bizarre. I have checked fuses- both fine. Visual inspection of wiring- fine. Changed the light & indicator controls at steering why- no difference. No voltage at bulb connectors to earth for dipped beam lights. Baffled. Anyone no what I have missed in finding the fault? I was thinking maybe a relay may have gone but I can't find them. I would really appreciate solving this problem with your help. Many thanks.