The dipped headlights on my 1986 F80 sometimes operate OK. Other times I can't get them to come on at all. The main beam (with blue light) and the spots are working fine. Can anyone please email me a circuit diagram for the lighting system. I know there are various relays and a resistor but without a schematic it's literally like working in the dark. As well as a diagram any experience of a similar probelm would be very good to hear about.