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Thread: what's the function of a horn relay ??????

  1. #1
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    what's the function of a horn relay ??????

    I'm working on a '47 Champ sedan. One of the horns works, and one trys to work, by using direct hookup to the battery. Neither will work through the horn relay. I removed the cover on the horn relay and the points open and close and I filed the points. Why aren't horns hooked up directly to juice via a switch ?? What does the relay do ??? Is there any adjustment for the non working horn ?? or WD40 ?? or Electronic spray ?? Relay fix ??

    BRAD

  2. #2
    Golden Hawk Member JDP's Avatar
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    The relay allow you to control a large current with a smaller switch and horn wire. Without it, you need a heavy duty horn switch and heavy gage wire. If the relay clicks and the horn does does not work the relay is probably bad or you have a bad connection or wire.

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  3. #3
    President Member mapman's Avatar
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    In addition to what JDP said the horn relay uses a ground switch to activate the circuit. This keeps live voltage out of the steering column and simplifies the system. The relay prevents a dead short. If you have had your horn go off going around a corner you have experienced the problems with the wires inside a moving part (the steering tube and wheel). Often you find on old cars that the horn button was disconnected (and sometimes a seperate switch or button has been installed).
    Rob

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    For the same reason that starter current isn't run thru the ignition switch. That's why they used to have a button on the floor; it could be heavy duty enough to connect high amperage and still not burn out. Manufacturers would have to utilize a monstrous switch inside the steering wheel in order to not burn out; carrying enough voltage to activate a horn.

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    quote:Originally posted by bradnree

    I'm working on a '47 Champ sedan. One of the horns works, and one trys to work, by using direct hookup to the battery. Neither will work through the horn relay. I removed the cover on the horn relay and the points open and close and I filed the points. Why aren't horns hooked up directly to juice via a switch ?? What does the relay do ??? Is there any adjustment for the non working horn ?? or WD40 ?? or Electronic spray ?? Relay fix ??

    BRAD
    Brad, it was mentioned on the Forum the other day that the relay terminals are not marked. It could be that the terminals for the battery and the horn button are swapped. That would still allow the realy to click, but it wouldn't blow the horn. try swapping them, and see what happens. If that doesn't work, swap them back again.

    Gord Richmond, within Weasel range of the Alberta Badlands

  6. #6
    Golden Hawk Member DEEPNHOCK's Avatar
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    http://tinyurl.com/yukj6y

    quote:Originally posted by bradnree

    I'm working on a '47 Champ sedan. One of the horns works, and one trys to work, by using direct hookup to the battery. Neither will work through the horn relay. I removed the cover on the horn relay and the points open and close and I filed the points. Why aren't horns hooked up directly to juice via a switch ?? What does the relay do ??? Is there any adjustment for the non working horn ?? or WD40 ?? or Electronic spray ?? Relay fix ??

    BRAD

  7. #7
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    The best bet is to bench test it out of the car. Before hooking mine up, I took it out and applied 12V to various pairs of terminals. With an Ohm meter, I determined which terminal was connected to the "closed when energized" contact. Marked it for posterity!

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