Horn keeps burning out

[beta250rrowner]

Hi guys, I'm tryna put two and two together here and make sense of a puzzling situation.

Basically I got my Beta 250RR all ready for MOT (UK roadworthiness test) and took it today.

It failed because the horn didn't work.

I've tested the horn previously and it was working with the momentary button I have for it.

It seemed to work strongly to begin with but now it doesn't work anymore. It works if it touches the voltage regulator which I found out by accident.

This is because the bolt hole that I screw the bracket to is on the right hand side of the head stock, below the steering lock.

It also works if I connect it directly to a battery, but not from the bike's system anymore.

The previous horn worked and then burnt out somehow. I don't know if it touching the voltage regulator broke it or not.

I've changed the fuse in the starter relay (which protects the horn circuit) to no avail.

Anyway I had to tap into the pink wire that provides the back light for the trip computer and then the grey horn activation wire. These are both connected to the momentary button.

I have stripped and cleaned the momentary button to check that it is not the cause of the problem.

Attached is the wiring diagram to help explain.

[beta250rrowner]

It was my fault as I wired the horn to the pink headlight indicator wire.

That wire provides 12v AC. But for some reason the horn was finding a ground through that circuit, but not a good one.

All the horn needs to work is to ground the grey wire.

So the grey wire to a momentary button and the other wire from the button to an earth point.

More information on my thread on TT

https://thumpertalk.com/forums/topic/12 ... t-14662520

[Clearvu1]

You see that big bundle of ground wires in the middle of the diagram? That's in the harness by the steering lock. Mine started coming apart, first the horn didn't work, then the brake light, at some point the voltage regulator and eventually the OI system. Rebuilt it and now everything works as intended.