Horn honks when right turn signal

I have a odd problem. Here are the details: 1966 Mustang 289. I am original owner.

Problem started while driving vehicle.

Turned on right turn signal and horn began to honk (odd sounding) off and on as if flasher was controlling it.

Left front signal and rear signals seemed to work ok.

Shortly after got a puff of smoke from turn signal switch area.

Replaced switch with new...same problem. Ruined new switch.

Took apart new switch and old (original switch) and found melted terminal on the switch where the right turn position would be (white wire/blue stripe).

Problem happens whether steering wheel is on or off.

I see no link between the horn and the turn signals in the wiring diagram.


Again this problem started while driving and I had not bee doing other repairs at the time. The car is 90% restored, so a lot of work has been done in the past.

Anyone else had this happen? Thanks !

I agree, but connector and wires on the harness side of turn sig. switch look good from what I can tell. Same with the main plug in at the firewall. Hard to see what is going on under dash though. I found an old switch that I am using for testing that is known good, but hate to short it out too. Will be buying my third switch soon !!

Making some progress...I have disconnected both horns and now the right turn signal works as it should. As soon as I connect either one of the horns the turn sig. stops and I get a big voltage draw. I am aware that this must be a shorted wire but unsure of where or how to find it.