Reproduction Parts for 1916-1964 Chevrolet Passenger Cars & 1918-1987 Chevrolet & GMC Trucks


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Clement Offline OP
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Greetings everyone. Hope you all are doing well. 1947 Fleetline Aerosedan. Just purchased. Previous owner had for 12 years. Wiring has all been redone. Trouble with the drivers side ( Left or high note horn ) . It does not blow. I took it off car, jumped it from the battery, it will blow your eardrum off !!! As soon as I put it back on car and all hooked up, it doesn't work. What am I missing ? Wiring all looks good, all connections are clean and tight. Took horn apart and all looks good inside. I did do a general search for this and even went back 5 years on this particular section...found nothing. Thoughts ? The right side ( low note ) works just fine. Thank you.

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Since the horn works okay by itself from the battery, the problem is outside of the horn.

Check that current is getting to the horn. There might be a loose connection somewhere, a broken wire might be somewhere in the circuit to the horn, or some corrosion on a connector.

Second on the list of possible culprits is the ground connection. Make sure that the horn is well grounded electrically. I've run into this problem a couple of times with my old trucks.

Corrosion happens!

Hope this helps, Dean


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Clement Offline OP
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Thanks. Will check in the morning.

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I strongly suspect it is a ground problem.

Both horns receive power from the same wire from the switched side of the relay. The right horn is actually further “downstream” from the relay than the left one.

There is a possibility that the power wire to the left horn is broken beyond the point where the wire to the right horn branches.



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I think "Jayhawker" did a thing on Youtube about horns recently.

You may want to check it out. dance

Best,

Charlie computer

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Clement Offline OP
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Ok..thanks for the advice. Maybe the power wire is the culprit. I will check that out , and that video , and all connections from the relay also. I took the horn off this morning, cleaned the area on the mounting bracket where the nuts and bolts go, cleaned the nuts and washers, and on the horn body itself cleaned where the bolts go. Put back on and nothing.

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I agree that you have pretty much eliminated the ground as the problem.

Here are a few more ideas.
- Move the right horn to that left mounting and the left horn to the right mounting.
- Use a test light/voltmeter to confirm if there is power at the horn wire.
- Trace the wire that connects to the left horn back into the harness where the right wire branches.


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Clement Offline OP
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Ok....sounds like a plan. Thanks, Rusty ! Will have time Sunday /Monday to try that. Going to first car show of the season here tomorrow !!! Saturday is a play day ! LOL Will keep you abreast of the progress.

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Originally Posted by Clement
Ok....sounds like a plan. Thanks, Rusty ! Will have time Sunday /Monday to try that. Going to first car show of the season here tomorrow !!! Saturday is a play day ! LOL Will keep you abreast of the progress.
I can' believe your going to drive that car to a show with only one horn working. LOL

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Just another suggestion, the horn mounts to a splash shield that is bolted to the radiator support and other front end sheet metal. While unlikely, maybe the splash shield that the horn is mounted to is the problem from a ground perspective. If you haven’t already, try using a jumper wire directly from the horn body to a known good ground on the engine. For convenience I usually attach to the vacuum advance steel tubing.

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Great suggestion Minetto! I was just assuming that the mounting surface had a good ground to the chassis.


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Clement Offline OP
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Good ideas...here is something weird.....While driving it today to the car show, as people were giving me " thumbs up " I honked the horn back.....BOTH horns were working ! As soon as I parked, I honked it to test it, and just the right horn sounded !! Never had this happen in my life !! Figure that one out. I think I am going to just leave it alone...but it is intriguing !!

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Reminds me of a machine that I worked on when I was a mechanic for IBM.

It was a computer-operated lathe that started its cycle okay, but when the bit was midway towards getting to the starting-to-cut point, the assembly that held the bit stopped moving. A lot of guys tried, unsuccessfully to diagnose the problem.

When I tackled it, a senior mechanic gave me the low down and said that the moving assembly "acted as if it hit a limit switch, which was at leash 7 inches away with nothing touching it." Hmmm.

The culprit ended up being a broken wire that came together (provided current) when the assembly was in one place and separated (disconnected the circuit) when the assembly moved. The wire was still in its insulation and was located in the middle of a bundle of wires that flexed every time the assembly moved.

I replaced the wire and then the machine got back into production.

So, maybe there is a broken wire going to the left side horn that is still inside the insulation and might be hell to find.

Cheers, Dean


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Clement: When car is parked start the engine and try the horn at different RPMs. Maybe it just needs that extra current to wake it up.

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Clement Offline OP
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Thanks, Dean and Dick !! Dean....that might be what is going on. Dick....will try the RPM Monday. It's interesting hearing the different ideas and trying them out . LOL

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Hi Clement

If I were you, I'd be looking for a place where your horn wire/wires maybe run close to your gear shift linkage.
If there is such a place, start wiggling wires there while someone tries the horn. :-)


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Also, put your car in the gear you were in when the horn worked (high maybe?) and try the horn then.


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Clement Offline OP
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Thanks, Ole. Yes, when I was driving down the road in high gear, it worked just fine. According to the great feedback I am getting from posters on here, most likely there is a short in the wire, or a loose wire somewhere. I am starting to think it is inside the steering column. The funny thing is, the right side horn works ONLY when it's parked in garage. When driving, BOTH horns honked correctly. Interesting. I will do more trouble shooting during the week. As long as they are BOTH working when I am driving, and they are nice and loud , ( which they are ) that is really when you need them 90 % of the time, I am happy. I will post my findings later.

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Originally Posted by Clement
. I am starting to think it is inside the steering column. .

Can't think how that could be since there is only one wire in there (not left & right ones) that goes to the relay.

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I agree with Dick that there is only one grounding wire from the switching side of the relay to the horn button. The fault appears to be on in the wiring downstream of power output side of the relay.

Based on my interpretation of the wiring diagram, that horn power wire branches under the hood just before the junction block on the inner left fender. I would check the terminals and connection in that junction block first. It would not surprise me if that screw was loose or there was some corrosion in that junction.


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Clement Offline OP
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I checked all that before, but will double check again.

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Clement Offline OP
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Finally figured it out , just now decided to post this. For those out there that responded earlier, thanks for all the help. I had checked all the wire connections on the junction block, per Rusty. I went a step further and decided to take the junction block off the car and check connections. Took sandpaper and made sure all connection points were metal to metal and not touching any paint. Ta Da !!! Both horns work just FINE and dandy now !! Again, thanks all for following and the help. It turned out to be a simple solution...those are the best kind !!

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Congratulations! And thank you for letting us know about the solution.

That is what drives you crazy about this classic car hobby. It seems like the simple solutions are so hard to find.


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Clement Offline OP
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Thanks !! I had visions of there being a short in a wire somewhere..........based on comments and suggestions.....ugh. I usually try to start with the easiest then progressively work to the hardest solutions. But, yes, sometimes a simple things slips by. LOL


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