Constant Horn

I

ilgrilleto

Junior Member
Hi Everyone,

Hopefully this is a simple one. When my steering wheel is assembled (horn ring), the horn is on, regardless of pressing the ring. At the moment i've disconnected the third terminal of the horn relay to stop myself from going crazy. Pictures are attached, am I missing a piece of the horn ring that prevents it from being grounded out immediately, or is my spring bad?

Also, ignore the electrical tape, new wiring harness is being ordered :)

Thanks,
Vince
 

Attachments

  • IMG_1411.jpg
    IMG_1411.jpg
    64.3 KB · Views: 62
  • IMG_1412.jpg
    IMG_1412.jpg
    97.3 KB · Views: 56
  • IMG_1410.jpg
    IMG_1410.jpg
    45.6 KB · Views: 50
Disconnect the horn wire where it comes out of the bottom of the steering gear box and reconnect the relay. If the horn doesn't blow with the horn button wire disconnected repair or replace the horn button wire. If the horn blows with the horn button wire disconnected either the relay is stuck or the wire between the relay and the horn button wire is grounding on something. If the wiring is original the problem is probably in the wiring. The original wiring insulation is rubber under a shellacked cloth loom. Over decades the insulation deteriorates, creating bare spots where the conductors can ground on vehicle parts. Attempting repairs is pretty useless because while you're repairing one bare spot you're creating others. Fortunately you're only dealing with a ground circuit so not much chance of a fire. Also check the horn button insulator pad under the steering wheel. They're just foam rubber and crumble after several decades.
 
Hi Dobie,

Thanks for the troubleshooting steps, I'll give it a shot. You mentioned a horn button insulator pad, do you have a picture or diagram, as it sounds like something i might be missing?

Thanks,
Vince
 
Excellent, I definitely don't have one of those in my assembly. I'll go ahead and order one as I'm sure it's pretty necessary to troubleshoot correctly :D
 
Constant horn blowing usually means that your horn button wire insulation inside the steering tube has worn off and is now in contact with ground (which completes the circuit, the same as if you pushed down on the horn ring).
Take note that there should be three wires going to the horn relay. The middle terminal gets the yellow wire (that is the power wire to the relay coil). The right side terminal should have a blue-yellow wire (that is an extension of your horn button wire which is ground and it completes the circuit, activating the coil). That middle terminal is internally jumpered to the relay contact input terminal. The left terminal of the relay is the relay contact output terminal. That wire goes to your horns.
Check all your wiring connections to the relay to see if they are connected correctly. Doesn't look like it to me.
Another thing that can happen is if you have taken the mechanism apart on the backside of the horn ring and accidentally put the nylon spacers in backward, that might cause problems also.
Make sure the collar of your horn button wire is all the way down on the end of the steering shaft. If the collar is sticking up, it pushes the horn button wire up closer to the back of the horn ring. You don't want that. This could be evidence of the horn button wire twisted inside the steering shaft. If it is doing this, replace the horn wire with a new one. they are still available new from the repro parts suppliers.
The horn button wire is NOT supposed to twist inside the steering shaft when you make turns. Thats why they designed it with that collar and little spring at the top, just to hold it loosely above the top of the shaft, but the wire should remain stationary inside the steering shaft.
 
I am not so sure I understand the purpose of the original insulating pad on that bottom plate on the horn ring assembly.
Theoretically, they are trying to isolate it from ground by having that plate mounted on the nylon standoffs, but so what. Don't the three screws in contact with that plate screw into the horn ring? Anyway, it is my understanding that the ground circuit is completed when that round plate underneath that bottom plate comes in contact with the metal hub of the steering wheel which is grounded thru the upper bearing to the dash if not thru the steering gearbox bearings to the car frame.
Notice how when it's all assembled correctly, that plate underneath is allowed to move a little bit when it hits the steering wheel hub. That plate is actually floating in its natural state between the nylon insulators and the thick round rubber insulator underneath the plastic center horn emblem. That way you don't need to smash the horn button with all your might to get the horn to blow, but how ever much force you use to blow the horn, that floating plate will move and stay in contact with the steering hub until you release the horn ring.
 
Hi 'Daves55Sedan',

Thanks for the writeup. If I leave the third terminal of the relay connected to the horn wire, the horn sounds, but if I remove the horn ring the horn doesn't sound so I don't think the wire is grounding out in the column, otherwise the horn would sound regardless correct? I'll double check the nylon spacers, that sounds promising. I just bought this car a few weeks ago so I'm working through my list of maintenance/repairs, so I really do appreciate the advice. I'll keep everyone posted.

Thanks,
Vince
 
Let me see if I can make you understand how it works this way;
The horns operate by completing the ground path of the circuit at the horn button, NOT by completing the power path of the circuit.
The power path terminates at the relay coil and is internally jumpered to the input side of relay contacts. The power path of the circuit is not switched. It is the ground path of the circuit that IS switched at the horn button.
Power flows thru the relay contacts to the horns only when the ground path is completed by pushing the horn button. Power wiring for the circuit doesn't even penetrate the firewall.
The reason why your horn is sounding constantly is because the GROUND path is erroneously completed by bad wiring insulation or some other means by which the grounding path for the horn is contacting with ground when it should not be.
You WANT the ground path to be completely isolated from case ground (body/frame ground) EXCEPT for when the horn ring is pushed.
When the horn ring is pushed, the button on the end of the horn wire comes in contact with the floating plate under the horn ring which hits the steering wheel metal hub which is grounded to case ground. When the horn ring is released, that plate backs away from the hub and causes a gap between the floating plate and horn wire, disconnecting the GROUND path.
The horn button is a "normally open" type of circuit.
Somehow, you have a "normally closed" circuit, because the usual path to ground has been bypassed.
 
Ok, I think I understand what you're saying (I read it a few times, the detail is greatly appreciated), however when I remove the horn ring and spring from the steering wheel, the horn doesn't sound, only when the horn ring and spring are installed (but not pushed). Wouldn't this indicate that the ground isn't being completed by bad wiring, etc? Only by a horn ring making contact in a way it shouldn't? Sorry if this seems like a dumb question.
 
ilgrilleto said:
Wouldn't this indicate that the ground isn't being completed by bad wiring, etc? Only by a horn ring making contact in a way it shouldn't? Sorry if this seems like a dumb question.
Click to expand...
No it's not dumb. Yes, if the horn wire insulation was compromised inside the steering shaft, the horn would sound regardless of whether you had the horn ring installed or not.
I noticed you are missing the original insulating pad on the bottom plate. Mine was real bad so I scraped it off then went down to a local auto parts store and got a roll of thin foam gasket material. I cut it out and cut out the slots around the three mounting screws and glued it on. Still not sure that's the problem though.
If someone has those three nylon standoffs turned around backward, that could be a problem, because the floating plate would then be able to fall against the ground path and the horns would sound without pressing the horn ring. Take a look at that. The floating plate in its normal position should have a gap between it and the bottom plate. It is held down by the thick round sponge rubber bumper under the plastic center emblem. That rubber bumper may be hard as a rock if it is the original one. If so, replace it with a repro.
 
After some experimenting, I'm definitely missing the insulating pad, and the nylon standoffs were upside down. I spaced out the floating plate with some tape for good measure and re-installed to a fairly functional horn. I've ordered a new insulation pad earlier today, so hopefully in the next few days i'll have a functional horn. I'll report back, but in the meantime, thanks a million again!

Vince
 
Hi Everyone,

I wanted to say thanks for all of your help, especially Daves55Sedan. With the nylon standoffs oriented correctly and a new (homemade) rubber bumper under the emblem, i now have a functional horn! Guess I didn't need that insulating pad after all!

Thanks again!
Vince
 
Many decades ago, when I went to replace the plastic center emblem on my '55 Fairlane, I noticed that the rubber standoff behind it was hard as a rock. I found an old spark plug boot (the one that plugs into the distributor) and after verifying it was still very pliable, placed it behind the center emblem and it worked well.
As far as that bottom rubber pad that was glued to the bottom plate, I wish someone would tell us what was the purpose of it. The fact is, that plate is continuously grounded while it is held out against the steering wheel hub in its normal position, but the horn does not sound because if the horn ring is not depressed, that plate is not in contact with the horn wire. So, it can't be to insulate the metal plate from the steering wheel hub when the horn ring is depressed right???
And if that bottom plate does actually come in contact with the well of the steering wheel hub when the horn ring is depressed, so what. You don't care because it is grounded also.
 
Dobie Gillis said:
Anti rattler?
Click to expand...

No. The bottom plate is stationary with respect to the horn ring assembly. The center metal plate however is a "floating" plate, held down by the thick rubber bumper under the plastic center emblem. It is permitted to move upward a short distance when the horn ring is depressed and the center plate comes in contact with the horn wire. The is no need for an anti-rattler.

The only thing I can figure is that the rubber pad on the bottom plate protects the zinc plating on the steering wheel hub when the horn ring is pushed down and maybe also that the rubber pad softens the landing against the hub when the ring is depressed. Just not sure.
 
How did you put the spark plug boot into the horn ring? Did you just lay it down on its side or did you trim it in some fashion?
 
How did you put the spark plug boot into the horn ring? Did you just lay it down on its side or did you trim it in some fashion?
 
You must log in or register to reply here.
Back
Top