Horn sounds constantly

[61Bob]

Greetings - a friend has been working on a '61. When he got the car the the horn was disconnected under the dash because it sounded constantly. Upon dissambling the steering column he thinks that part 13A816 (diagram below) is worn and causes the circuit to be continuously active. He has replaced all other available horn parts except this one and has been unable to source a replacement. Does anyone know where to obtain this or have any other solution? At this point I haven't seen the disaasembled steering column myself, I'm only relaying what he's told me so far.
TIA!

[MN63Tbird]

Bob, I would recommend your friend get a wiring diagram for the car. That helps trace the wires. You mentioned part 13A816 which is not in the diagram are you referring to 13A824 the horn button? if so those can be purchased from various TBird vendor sites. The way the horn works is that there is a relay in the front of the engine on the left side that when activated will send power to the horn to make it sound. The horn is grounded to the car to complete the circuit. Power runs to the relay . To activate the relay there needs a ground circuit to the car. The blue yellow wire from the relay provides that ground circuit.

That wire goes across the wiring harness in the engine compartment under the dash and then up the steering wheel column. It is connected there to the horn button on a spring. The horn button I believe is copper. That button rides against the back of the steering wheel with its spring holding it tight against the ring. . When you press the horn ring it makes a contact with that ring on the steering wheel and completes a circuit to the steering wheel shaft. That shaft if properly connected at the rag joint will ground to the car. So by pressing the horn ring you are in essence creating a ground to the car from the horn relay. So by knowing your horn runs all the time means that somewhere that blue yellow wire is constantly being grounded. The issue can be a broken blue yellow wire somewhere that touches the body of the car. Most likely area would be near the horn button. You need to pull the steering wheel to find that out.

MN63

[61Bob]

Thanks MN63Tbird for your detailed response and I will forward it to him. Perhaps there is a part of the diagnostic process that you described that he has missed. I can see the part 13A816 in the diagram, it is the one of the two triangular pieces with the 3 holes that look identical to each other. Of the two, it is the one closest to the steering wheel. He believes that this piece acts as an insulator (now worn to the point of ineffectiveness) that keeps the steering wheel from making contact with the surface undernearth and completing the circuit as you describe. Thanks again.

[MN63Tbird]

My mistake I do see the 13A816 now. If my memory is correct it is a little plastic gasket. If your friend has the steering wheel pulled off and he hooks up the horns and the horn does not go off that gasket would be a source of the problem. A quick search of my Tbird vendors did not turn up anything. If he cant find one from someone parting out car he may be able to fabricate one. A thin piece of polypropylene HDPE or maybe PET may work. The next challenge is to adjust the 3 screws on the back that go through that gasket to hit the correct area for the horn ring to work. A continuity meter attached to the outer ring 13A808 and the center shaft will give a good idea when you have the correct adjustment. Good luck!

MN63

[WNC Bird]

Bob,

I don't know if you resolved your issue but I just had the same problem after replacing the detent plate and turn signal switch.

The black circular gear indicator plate, I believe is called the horn switch, has a spring facing the driver that rides on the back of the steering wheel as MN63 indicates. The other side has a stud where the horn wire connects to the horn switch. The horn wire runs through a rubber coated wire strap.

In my case I put everything back together and everything worked, except the horn would blow constantly. Disconnected the blue yellow wire problem goes away so I knew I was something I just created since it used to work fine. Plugged the wires back together and removed the steering wheel, again. Problem was still there so I knew it wasn't the steering wheel mechanism. It was somewhere between the plug and the spring. I was concerned about the new wire i pulled through the steering column so with a meter i checked it to ground. Wire was fine.

The culprit was the stud off the back of the horn switch has a bare connection and it was hitting the supposed to be rubber coated wire strap. I must have move something during my repair. Replaced the metal strap with a nylon one and problem solved.

Maybe something your mechanic can check.

MN63

I couldn't have figured it out without your detailed troubleshooting guide. Thank you