| MICHV8 | -- 05-07-2020 @ 11:05 AM |
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If a horn sounds with only the power wire and no ground wire and the horn bracket is insulated from the fender, does that simply mean an internal short in the horn itself? update: the horn works fine when off the car with an external battery... only works with either wire combination touching + and - posts. BUT when on the car, the horn sounds when one of the horn wires is touched to 15Y power (from new headlight harness 40-11646) and doesn't sound when the other horn wire is touched to the same 15Y, but gives a quick spark. Is this a wiring harness short? This message was edited by MICHV8 on 5-8-20 @ 8:48 AM
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| PowerSerg | -- 05-08-2020 @ 10:37 AM |
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what year and model of car do you have? is it positive ground or negative ground wiring?
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| TomO | -- 05-08-2020 @ 10:54 AM |
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I am assuming that you are working on your 36 roadster. You will need an ohm meter to check this out. Your horns should be isolated from ground and the yellow wire should have 6 volts on it. The horns should blow when the horn button completes the circuit to ground via the blue wire with a yellow tracer. I don't know what wire 15Y is connected to. Use the color codes on t6he wiring diagram to describe your problem. Tom
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| CharlieStephens | -- 05-08-2020 @ 12:02 PM |
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The horns are not isolated from ground, they bolt directly to the chassis (which is ground). The current comes into the horn and then out through a wire that goes to the horn button where it is grounded. Charlie Stephens This message was edited by CharlieStephens on 5-8-20 @ 12:03 PM
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| MICHV8 | -- 05-08-2020 @ 2:18 PM |
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Charlie Stephens, This is a 34 whose horns have 2 wires...one receives power from 15Y and the other receives ground from 12Bl-Y which is the horn button circuit at the bottom of the steering box. My horn is not connected to 12Bl-Y, but sounds when one wire is touched to 15Y. So the question to me is, where is the horn getting the ground when it is on the car? I have isolated the horn bracket from the headlight bracket with a gasket. i also put a rubber washer on the bolt under the fender that secures the horn bracket to the headlight bracket...still the horn sounds with no ground wire attached. So the million dollar question to me is, where is the horn getting the ground? The headlight bracket has the normal stock rubber pad ... Tom(), 15Y is the main power from the starter switch battery side I had initially assumed that my steering column horn wire was grounding so I started testing without the horn ground circuit (12Bl-Y) and discovered the current situation
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| CharlieStephens | -- 05-08-2020 @ 2:33 PM |
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What you are describing shouldn't be happening unless someone rewired the horn in which case I would expect to see only one wire going in and the horn itself being grounded. I am sorry to say I have no suggestions. Are there any local EFV8 Club members that could stop by and maybe spot something? Charlie Stephens This message was edited by CharlieStephens on 5-8-20 @ 2:36 PM
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| MG | -- 05-08-2020 @ 3:23 PM |
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1934 Ford Wiring Diagram:
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| MICHV8 | -- 05-09-2020 @ 10:38 AM |
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positive ground thanks MG...matches the schematic that came with the harness It seems to me the fender or fender brace is somehow providing ground, but I sure don'e see how. I've even tried wrapping the horn bracket bolt threads with electrical tape where the bolt runs through the headlamp bracket and still same problem...horn sounds with no ground wire attached. Even took horn apart and everything looks ok...mystery.
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| 37RAGTOPMAN | -- 05-09-2020 @ 11:39 AM |
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HI MICHV8 how about a few photos I think all FORD horns had 2 wires, in the 1930's my 37 has 2 wires,and I Have 2 horns, I have never saw a horn with a internal short, but I guess anything is possible, are you sure to have original Ford Horns and not a repros ? let see a photo of the inside of the horns,wiring connections. using a volt meter you should be able to tell where the short is my 2 cents 37Ragtopman like they say a photo is worth a 1000 words,
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| MICHV8 | -- 05-09-2020 @ 1:03 PM |
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37ragtopman... The horn works fine off the car, so a horn internal problem not a candidate, right?
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| 37RAGTOPMAN | -- 05-10-2020 @ 7:42 AM |
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HI MICHV8 I think you have a short in the horn, do you have one or two ? look at it very closely, any bare wires,, touching something they should not ? too long a screw at wire connection making a ground ? do you have a volt ohm Meter, to test it, ? a volt ohm meter is a must when trying to find electrical problem, I bought a Craftsman, meter, around $40.00 it even has a button that you can hold up to a household 120 220 volt circuit and has a alarm that lights up and buzzes, comes in real handy around the house or garage, when you want to test a outlet,to see if it is LIVE, let hear how you made out 1937Ragtopman post a few photo's this may help...
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| MICHV8 | -- 05-11-2020 @ 6:48 AM |
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37Ragtopman Once again, wouldn't an internal short show up off the car as well? The only thing I see different from the passenger side and driver (problem horn) is that the driver horn bracket looks like a repro...are the small sleeves (rubberr?) between the 2 metal plates the possible problem?
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| 37RAGTOPMAN | -- 05-11-2020 @ 7:16 AM |
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hi MichV8 how many wires coming out of the reproduction horn,? if one horn works correctly and one does not, that what you are telling us, did you take the cover off and inspect the insides,? I suspect that the repro horn is set up to use a relay,and would be rewired to work that way, I try staying away from these parts, seems like always presents problems down the line, let hear form you, 37Ragtopman MAINE post a few photo's to see what you are dealing with,
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| TomO | -- 05-11-2020 @ 7:55 AM |
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The horn motor MUST be isolated from ground on the horns with out a relay. The horn works fine when off of the car because the only path to ground is through the wire that you have connected to the battery. When you have it mounted on the car, you are getting a ground connection through the mounting. When you have a horn relay, the horns must be grounded to the chassis, because the relay provides the 6 volts. The horn button ground picks the relay and the voltage is supplied to the horns through the relay points. Mich, I don't know where the horn motor is getting it's extra ground, but you can try to isolate it from ground by placing a thin rubber gasket between the mounting bracket and the horn motor. You may have to use phenolic or other non -conducting washers on both the screw and the nut. You could just cut out a couple of washers with a gasket punch and put a piece of shrink tubing on the bolts. If that doesn't work, PM 3W2 and ask him for advice. He is very knowledgeable about the 34 cars. Tom
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| MICHV8 | -- 05-11-2020 @ 8:06 AM |
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37Ragtopman and Tom() here are a couple photos...the black face horn works fine and the gray is the problem horn
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| MICHV8 | -- 05-11-2020 @ 11:17 AM |
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I cut 2 gaskets from some extra top grain material and inserted them between the 2 plates (with the rubber spacers) on the horn bracket...solved the mystery ground. I'd sure like to know what is different between the passenger original bracket and this driver side repro, but I'm going to leave well enough alone for now. Thanks to all for the input and help...
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