harri, i had the same problem, the wiring diagram in most manuals is for the early models, sounds like yours is the k3 or f2?. the solution is to remove the black wire from the horn just leave the light green one attatched. then the spare horn terminal goes to earth via a short wire, i just earthed to the horn mounting bolt. on these models the + current goes to the plastic connector in the handlebar switch first, then via the l green wire to the horn, then to earth, it does not earth in the switch itself, when you press PA it diverts + current to the headlight main beam for flash. the old black wire at horn is not now used, just tuck it out of the way. If not sure give me a ring on 07870112945, regards Mick