Not the same problem but sounds, no pun, related.  My horn works
intermittently.  I used to think it was the rain but is happens in all
weather now.  For a while it only seemed to work if I had a passenger:)
At night its behavior is the best.  When I press the horn and it fails
to sound, my lights go dim!

I am hoping to get to look at this when the weather improves.  Any
suggestions, i.e., replace the horn, wiring or both?

Cheers Dave

PS: Most of my passenegers thought I was loonie for randomly pressing
the horn.  I just told them that every second somewhere in the world
someone was blowing the horn.  It just happens to be my turn:)