We moved cross country, the bikes bouncing on trailers time to time in spite of well secured. The 2008 Road King made it ok except when ignition is turned on the horn sounds. Only way to ride it is to pull the wires off the horn. Switch tests ok and in wiring diagram there seems to be no relay.

Has anyone ever ran across this?

 

You state "Switch tests ok".
How exactly did you test the switch?
The factory horn requires a positive voltage and a negative/ground.
The frame generally will provide the ground.
The switch at the handlebar will provide the positive.
Do the wires at the horn have constant voltage?
Did somebody change grips, levers or handlebars and accidently pinch the wires at handlebar switch clamp?
*Did somebody run a ratchet trough the triple tree and accidently ratchet down the wires at triple tree thus causing some squishing/damage of wires.
Then perhaps damaged wire got energized by the wire next to it and that is causing the horn blast.

 

You state "Switch tests ok".
How exactly did you test the switch?
The factory horn requires a positive voltage and a negative/ground.
The frame generally will provide the ground.
The switch at the handlebar will provide the positive.
Do the wires at the horn have constant voltage?
Did somebody change grips, levers or handlebars and accidently pinch the wires at handlebar switch clamp?
*Did somebody run a ratchet trough the triple tree and accidently ratchet down the wires at triple tree thus causing some squishing/damage of wires.
Then perhaps damaged wire got energized by the wire next to it and that is causing the horn blast.