I have a 51 plate Ford KA. One of the full beams is not working. I have changed the bulb and also checked the fuse but this has not solved the problem. Can someone tell me if the light stalk/switch could be the problem or would this affect both lights at the same time? If it is not the switch, would anyone know how best to trace the wiring?

Tom Dean, August 2009

remove the plug on the bulb and test for power . one is earth one is low beam and one is high beam. sometimes the plug gets hot through bad contact and melts the plastic onto the terminal. if this is the case best get a plug from breakers and join to old wiring.

amigo, August 2009

Hi Tom, if one high beam is working it will not be the switch, as it supplies the voltage to the high beam relay, which sends the supply out to fuses 10 (left) 11 (right) (bottom row of the fuses 1~11 from left to right) then to the headlight units, if the high beam warning light is working on the dash fuse 10 is OK The earthing for the lights is all commoned together inside the light unit and is made to earth at a point under each light unit but as the other lights are working you should be able to rule out an earthing fault.
If you would like a copy of the wiring diagram contact me on nige110162(at symbol)hotmail.co.uk and I'll mail you the info

nigel, August 2009