circuit tester you need, then you need the colour code for the wiring.colour code i can give you if needed.most sealed beams have a 3 pin plug at the back of the unit, 1 is earth, the other 2 are dip and main beam,find the earth wire and earth to the battery, then run a wire from the positve terminal on the battery to the light unit and test them that way, as for the switch a tester would be better, you will have power at the switch , short piece of wire and connect to live terminal then touch each wire in turn, make sure that none of the wires are earth other wise you have sparkys. if stuck email me. jim