This week my NOS GMC horn button arrived in the mail from the dealership, and the spring disc from a VERY helpful board member. When I installed everything in the 67 3500, the horn did not work (I was not surprised).
So I removed the horn button and fooled around with the assembly. When I touched any of the horn screws with a screwdriver and the horn cup together, the horn would honk, but not with the button pressed. The relay would also click like it is supposed to.
So I disassembled all of it and cleaned everything, then reassembled it again. Now not only would the button STILL not activate the horn, the screwdriver/screws trick no longer did either. The relay no longer clicked either. I went through the assembly multiple times but found nothing wrong. I even cleaned/buffed the steering wheel under the disc to ensure good contact and ensured it was not pinched. I also checked the fuses. And I recently replaced the turn signal switch with a brand new AC Delco one.
This morning I bought a new horn relay and installed it, but...you guessed it...NO HORN!!!!
I went though dozens of horn threads, but NOTHING that I tried worked. Anything I may have overlooked? And why would cleaning the horn assembly cause to stop "jump" honking?