1931 Coupe Horn Wire

[1931rumble]

I bought a 1931 Model A Rumble seat Coupe one week ago. The Aooga horn did not work. I followed the discussions on the Ford Barn Forum and now it works with 6 volts applied to the horn. The horn button does not activate the horn. I took the light switch off of the end on the steering column and then tried to remove the horn rod. It is too long. I disconnected the bolts to the steering drag link and removed the steering column support under the dash. I could get the horn rod out to within five inches but the top is in the way.


Next I remove the four tabs that hold the horn button to the end of the horn rod. Cleaned the pieces in the horn button and before I put it all back together I want to check the current or continuity of the horn button.



Is there a way to test the horn wire for continuity with the horn rod in the car? I can replace the wire but I don't want to if I don't need to. Any ideas?

[Jim/GA]

Yes you can.

Use an ohmmeter or a powered test light with one lead touching the button on the end of the horn rod, and one lead touching the outside of the horn rod or a clean ground. Now have your trusty assistant press the horn button and watch for the meter to show the circuit is closed, or the light lights up.

Make sense?

[1931rumble]

Thanks. I will get to work in the morning.

[1931rumble]

I cleaned the end of the horn rod end with Emory cloth first. Connected the clip of the test light to the battery cable at the started and touched the end of the horn wire and it did not light up. Then I had my helper push the horn button with the test light on the end of the horn wire. It lit up!


Then I cleaned the inside of the light switch where the horn wire contacts the horn in the light switch. Reconnected the light switch. Checked to make sure that the cowl and head lights still worked. Then pushed the horn button. No Sound.


I do not see an easy way to take the light switch apart. I have the Model A books that explained how to remove and clean the horn rod wire and remove the horn button and how to repair and clean the horn itself. I can not find a diagram or explanation of how to check the light/horn switch.



Is there a diagram in one of the books?

[Jim/GA]

Originally Posted by 1931rumble

I cleaned the end of the horn rod end with Emory cloth first. Connected the clip of the test light to the battery cable at the started and touched the end of the horn wire and it did not light up. Then I had my helper push the horn button with the test light on the end of the horn wire. It lit up!


Then I cleaned the inside of the light switch where the horn wire contacts the horn in the light switch. Reconnected the light switch. Checked to make sure that the cowl and head lights still worked. Then pushed the horn button. No Sound.


I do not see an easy way to take the light switch apart. I have the Model A books that explained how to remove and clean the horn rod wire and remove the horn button and how to repair and clean the horn itself. I can not find a diagram or explanation of how to check the light/horn switch.



Is there a diagram in one of the books?

Before taking the light switch apart (I don't think that's your problem) investigate inside your horn.

Remember that one wire in the horn is hot all the time and connected directly to the battery. It will short out very easily and really spoil your day. Best to disconnect the fuse (if you have one) or the battery before taking the cover off.

Just like you tested the horn rod, connect the lead of a powered test light to the horn switch wire and the other lead to any convenient ground. Have someone press the horn button for you. You should see the test light light up. If so, the problem is with power to the horn or the horn itself.

If not, there is a problem with the horn wire.

[1931rumble]

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Thanks for your help. I will get started with testing the horn. I know the horn works with 6 volts applied directly to the two terminals on the horn.

[1931rumble]

I disconnected the power and removed the horn cover. I reconnected the power and used the test light to locate the hot wire on the horn. Tested the hot wire to the engine block and the light lit up. My helper pushed the horn button while I held the test light to the non hot terminal of the horn. No light.



I tested the hot side of the horn to the electric motor in the horn with the test light. It lit up every where except the top part of the horn that gets power from the horn button. I guess it's the horn wire?


How do I test the horn wire? I can see the two wires that come from the horn and go into the wiring harness. Since they are not color coded after the wire leaves the horn I will start checking the wires that go into the light switch.

[Jim/GA]

Look inside the frame up by the horn, down out of sight, for a horn relay that someone might have added. A black box with 3 or 4 wires coming out of it. Probably also wrapped with electrical tape.

[1931rumble]

No black box. I redid the 6 volt battery charger to the horn leads with the battery disconnected and the horn worked. The battery is new and has a battery tender connected, except when I reconnect the battery.



I did take the light switch apart and cleaned the end of the horn wire that connects to the horn. Used dielectric grease on the connections after cleaning and reassembled. The lights work.



I was going to hook up a jumper wire from the starter to the horn to see if that will make it work too.



Any other ideas?

[1931rumble]

An update. I ran jumper wires from the battery in the Model A to the horn and it worked. So the short or disconnect is somewhere between the horn and the switch, I think.



I just wanted to make sure that the battery would make the horn work.