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Premium Member
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344 Posts
Discussion Starter #1
I took advantage of the brief 40+ degree weather around me (after a week of sub-freezing high temperatures) to go for a ride today. All went well until I was about half a mile from my house on the return leg. Suddenly, my horn started going off on its own. At first only intermittently and weakly, and only if I revved to over 3K RPM; then, after a few minutes, more loudly and nearly constantly (though varying in loudness).

I pulled over, put the bike in neutral and killed the engine with the kill switch, but the horn kept going. I had to turn the ignition to OFF to get it to stop. But, if I turned the ignition back to ON, it wouldn't go off again until I'd started the engine.

I have a Stebel air horn so when it gets to full volume it's REALLY loud, and even when squeaking a 1/4 power or so honk it's still pretty loud. Normally there is no way to partially honk the horn, so the fact that it's varying in volume must be a hint as to what's going on -- I just don't know what.

Obviously this is an electrical issue, but where should I start to figure out the problem? In the interest of full disclosure, the only thing I've done with the bike lately is in fact electric related, but I don't see how it could have affected the horn: I put on a Powerlet outlet just this past weekend.
 

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Simple Solutions
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965 Posts
is the horn tied into the factory wiring??? were is the wiring for the powerlet outlet is that running straight off the batt or is it pulling from another wire???


if i were to guess it would be in the wiring around the hornswitch or the switch itself... but again these are just guesses ??
 

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Premium Member
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344 Posts
Discussion Starter #3
is the horn tied into the factory wiring??? were is the wiring for the powerlet outlet is that running straight off the batt or is it pulling from another wire???


if i were to guess it would be in the wiring around the hornswitch or the switch itself... but again these are just guesses ??
the horn is on the factory harness, and the Powerlet thingy I plugged into the accessory lines under the right seat panel using bullet head connectors.
 

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Vintage bike addict
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859 Posts
I'd spray contact cleaner in the horn button and check the horn relay if there is one.
 

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The Professor
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3,147 Posts
Clean the horn button contact and bend the contact back a little. :beerchug:
 

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Premium Member
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344 Posts
Discussion Starter #7
I got it. The contacts on one of the horns must have gotten dirty from road salt, to the point where it was passing current into the entire outer shell of the horn. Then, when I got to about 3K, the engine vibration was enough to cause that outer shell to lightly touch the bolt that mounts it to the fork, which is attached to the frame, which made a circuit back to ground -- and then, honk! The faster I went, the more the vibration would cause it to touch the bolt more hard and make better contact = louder honk.

I unplugged one horn then the other and isolated it to the one on the right, then sprayed contact cleaner into both plugs and the problem went away.
 

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Premium Member
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4,778 Posts
Good detective work!
 

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Jesus-Family-Coffee-Bike
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95 Posts
don't you wish all the problems ended that easy? ~dw
 
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