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Do I really need a relay for a after market horn?

Discussion in 'The Garage' started by projectxs650, Jul 15, 2012.

  1. projectxs650

    projectxs650 XS650 Addict

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    I bought a used wolo "bad boy" horn off of craigslist. Its your basic compact horn, but still very loud. I spent a good hour trying to wire it up, followed the directions on wolo's website. After a ton of profanity I could not get it to work, just for the heck of it i hooked the battery directly up to the horn, positive to positive and negative to negative.

    It went off and surprised me cause i didn't think it would work.

    What thats telling me is that the relay doesn't work, or my wiring is somewhat off. I doubt its the wiring though because i followed everything to the tooth, and i'm generally very good with wiring.

    So i'm wondering, do i really need this relay? i'll still probably put a inline fuse. anything wrong with that?
     
  2. Dorzok

    Dorzok XS650 Enthusiast

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    you need relay to protect the horn switch and associated wiring from the amperage draw of the horn. don't know what a fuse would do for that?

    let me clarify. a relay is simply a heavy duty switch that is operated by the horn switch. so, the power through the horn button remains the same and the power to the horn is handled by the relay.
     
  3. yamaman

    yamaman xs650 addict

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    The factorx horn (same as the starter) button earths through the bars. Try putting a jumper lead from the bars to the motor, see if that changes things, a common problem on these, cheers

    Posted via Mobile
     
  4. projectxs650

    projectxs650 XS650 Addict

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    are relays universal? as in the one that i got with the horn is only specific to that model horn? or could i just swing by radio shack and pick up a identical one of what i have.
     
  5. projectxs650

    projectxs650 XS650 Addict

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    What if i we're to wire it independently? directly to the battery/ground with no connection to the circuit and/or other wires?
     
  6. yamaman

    yamaman xs650 addict

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    you can chuck your relay away, but the horn button wont last long without it. The horn relay (found on most anything with a horn) is there for a reason, keep it. Not hard with a test light or meter to see if its working or not. Did you have a working horn before you put this you beaut one on?

    Posted via Mobile
     
  7. Mister Mellow

    Mister Mellow Big Dreams, Thin Wallet

    It's quite possible to run a horn without a relay, but the size of the switch required to do that would be ridiculous, because it would have to be beefy enough to feed the horn at the required amperage. Relays are ingenious little devices because they do the work ("relay" current from battery to horn) so your horn switch doesn't have to. All the switch does is actuate the relay, which doesn't require a lot of amperage.

    In the simplified diagram below (not from a Yamaha wiring diagram), the circuit from the ignition switch to the horn switch is low-amperage. When actuated, the horn switch passes a small amount of current to ground. As current is flowing through the relay coil, a magnetic field is created, which physically closes a larger-current switch (dotted line). What the diagram doesn't show is that the wire from the ignition switch to the horn is a larger one, capable of passing the current that the horn needs to operate.

    [​IMG]

    Sorry if this is something you (OP) already know - I can't help myself sometimes.
     
  8. projectxs650

    projectxs650 XS650 Addict

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    no that always helps to refresh. I think my best bet would be to test the relay and see how it is, maybe with the original stock horn i had. if that doesn't work then switch it out and try the wiring all over again.

    what i'm wondering though, is that i think i see my horn button only having one wire connected to it, a pink one? i'm assuming that would be the positive, but where or how is it grounded?
     
  9. yamaman

    yamaman xs650 addict

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    Ok, I'm typing this slowly, caus I know you cant read real fast.
    As shown in the diagram above, the horn button completes the earth circuit. That is, when you push the horn button, you push the pink wire against the metal of the handlebar. As these bikes have rubber mounted bars, you need a connection from the bars to the chassis for this to work. Often this connection is accidently broken when people stuff around with the bars. Does your electric start work, it relies on the same link. One easy way to test this is take a length of wire and hold the bared ends against the bars at one end and the engine fins at the other. Now use your 3rd hand to press the horn button, does it work now? Cheers :D

    Posted via Mobile
     
  10. jd750ace

    jd750ace Front Toward Enemy

    You can run that horn without a relay, but be prepared to listen to it wail uncontrollably until the wiring catches fire or the battery dies. If you are trying to use the original horn relay it won't work. Go to the auto parts store and get one of the relays that are usually hanging right beside the air horns.
     
  11. Grinder

    Grinder XS650 Guru

    The pink wire on the horn button actually provides the ground to the horn. There should be a brown(switched 12V) wire going to the other terminal on the horn. The two wires going to the stock horn would go to terminals 85,86 on the relay. Then run a wire from the positive battery through a fuse to terminal 87 on the relay. Run a wire from terminal 30 on the relay to the Wolo positive and ground the other Wolo wire. When you push the horn button it engages the relay and passes the battery voltage through the relay to the horn.
     
  12. pamcopete

    pamcopete Ride.Enjoy.Life is Simple

    Well, if the horn is such a monster and draws a lot of Amps, then you do not want that current to go through the ignition switch or require you to increase the size of the main fuse, so the horn should have its own fuse directly to the battery. This will also prevent the horn from possibly interfering with an electronic ignition.

    [​IMG]
     
  13. jd750ace

    jd750ace Front Toward Enemy

    Totally agree with Pete's last post. Even in my truck, every air horn I've installed I have run an independent wire for the horn main line, and used the existing control circuit and left it as intact as possible. These things will dim your lights at idle. I have never used a wolo, but have installed 4 Stebels. I installed mine on my Roadstar with a compressor off a crashed Gold Wing and a set of trumpets off an old Fiat one of my buddies uses for rally car parts. LOUD, especially when you tune the horn frequencies by (protected) ear! Do not do this inside the house or garage!
     
  14. Mister Mellow

    Mister Mellow Big Dreams, Thin Wallet

    Agreed. Although I posted the schematic more to explain how a relay works, it also shows that power from the horn is on its own fused circuit, separate from the ignition switch. The ignition switch in this diagram only powers the switch and the low-current side of the relay.

    I haven't been home to look at how the XS650 is actually wired, but I imagine it's not too much different than shown in the example.

    EDIT: Ah, I see that my diagram doesn't include an independent circuit. I should have examined it more closely. In reality, I would wire as shown in your diagram, which I just noticed includes the independent circuit. Thanks for making that edit to the drawing.
     
  15. uebe

    uebe XS Goober

    I've seen simplified wiring diagrams that do not show a starter relay. Are these wrong? Wouldn't a starter motor also need a relay for the same reasons a horn would? I see that the stock harnesses incorporate a safety relay, presumably to prohibit "restarting".
     
  16. Grinder

    Grinder XS650 Guru

    The simplified wiring diagrams here that use an electric starter all have a relay. It's also called a solenoid.
     
  17. It's called a starter solenoid and does exactly the same thing. Starter relay would be better name for it.
     
  18. Doh...amazing what can happen in one minute..
     
  19. pamcopete

    pamcopete Ride.Enjoy.Life is Simple

    It's called a solenoid because that is what it is. It consists of a winding of wire around a tube with an iron rod in the center that moves in response to the current through the winding to draw the iron rod through the tube where it actuates a set of contacts to send the current from the battery to the starter motor. This type of construction can handle more current than a relay. In earlier designs the iron rod also served to engage the starter motor gears themselves. Solenoids are also used as mechanical actuators with no electrical function.
     
  20. projectxs650

    projectxs650 XS650 Addict

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    So i've got it setup now, and its running, almost.

    I can't seem to get the stock horn button to work. But i did get the horn itself to go off. i need to figure out how to get the pink ground wire to function with the button and connect to the frame.

    is their a horn button schmatic anywhere?
     

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