Volt reading at horn

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  • 20jlr
    • Jan 2026

    #1

    Volt reading at horn

    My voltage when testing with the horn button pressed is 9.6 volts. I tested the battery and it is reading 12. Is this normal? if not what should the voltage be, and or any recommendations to fix it. The bike sat for 15 years prior to me getting it this summer. The horn has not worked as long as I have owned it.
  • robertbarr
    Forum Sage
    Past Bard Award Winner
    GSResource Superstar
    • Sep 2005
    • 2721
    • Joliet, Illinois

    #2
    I would think that at 10v (more or less), you'd get at least a sickly warble out of the horn. Try jumping it directly just to make sure it beeps for ya.

    You should have power going to one side of the horn whenever the ignition is on. The button provides the return path to ground (provided the button works and doesn't have a mess of resistance).

    Low voltage is the result of current flow through the total resistance of the harness -- including any dicey connections. You can reduce the voltage drop a number of ways. The most obvious is to clean up the connections; a less obvious method is to reduce the current flow through that resistance, and you do that with something like a headlight relay kit, which removes the headlight load from the harness & sends power directly to your headlamp.

    When I added one of these kits to my '81 GS1000, my formerly sickly horn regained its health and vigor, without ever messing with the horn to begin with. I just wanted (and got) better illumination. You can research these on this site, and at a source of quality kits with the unlikely name of Eastern Beaver. Good stuff, very fair prices.
    and God said, "Let there be air compressors!"
    __________________________________________________ ______________________
    2009 Suzuki DL650 V-Strom, 2004 HondaPotamus sigpic Git'cha O-ring Kits Here!

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    • 20jlr

      #3
      Thanks when testing I noticed my light dimmed quite a lot when i was testing the voltage. I believe the horn is shot as I jumped it out and nothing happened. I was looking at the basscliff website about the horn relay as well to try to get the voltage for the horn off the old wiring as well.

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      • Guest

        #4
        Horn no longer worked on one of my GT750s. Got a Wolo horn + relay at an auto parts store & now have an impressively loud horn.

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        • hannibal
          Forum Sage
          • Jun 2015
          • 1033
          • Washington DC

          #5
          Ideally the voltage at the horn should match battery voltahe. Of course this never happens but the closer, the better.
          Jordan

          1977 Suzuki GS750 (My first bike)
          2000 Kawasaki ZRX1100
          1973 BMW R75/5

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          • wymple
            Forum Sage
            Past Site Supporter
            • Apr 2014
            • 1893
            • SE Iowa

            #6
            The horn on my 850, not running,with a good full battery, only, puts out a tiny contact beep, akin to a starter solenoid that just clicks. And I get 12V at the horn. Start the bike and it'll wake you up. It's been this way for the 3 years I've had the bike and never changes. I've not investigated it deeply because the horn works.

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            • Guest

              #7
              I bought some cheapies on Ebay as mine were a muffled "meep" sound. They were the same decibel level as stock. I think I paid 5 bucks for the pair shipped. However, if you have something against cheap Chinese crap, don't buy them.

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              • Redman
                Forum LongTimer
                Past Site Supporter
                • Mar 2004
                • 13717
                • Michigan, west Michigan

                #8
                Originally posted by 20jlr
                My voltage when testing with the horn button pressed is 9.6 volts. I tested the battery and it is reading 12. Is this normal? if not what should the voltage be, and or any recommendations to fix it. The bike sat for 15 years prior to me getting it this summer. The horn has not worked as long as I have owned it.
                Yes, voltage at horns should be about battery voltage with horn button presses .....and..... without the horn button pressed.

                The circuitry is such that is positive power connected to the horn all the time (when key on) to one connection of the horn(S). And the other connection is to the horn button, and so the horn button when pushed connects to the negative/ground.

                Need to understand that completely, forward and backwards, in order to troubleshoot the system. Can not find what is abnormal if don't know what normal is. Can't find why it doesn't work if don't understand how it should work.

                .
                http://webpages.charter.net/ddvrnr/GS850_1100_Emblems.jpg
                Had 850G for 14 years. Now have GK since 2005.
                GK at IndyMotoGP Suzuki Display... ... GK on GSResources Page ... ... Euro Trash Ego Machine .. ..3 mo'cykls.... update 2 mocykl


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                • 20jlr

                  #9
                  thanks guys. The horn button was not making good contact. There was a lot of rust under the switch. Cleaned it up, Bought a new horn as well. solved the voltage problem as well by cleaning up the rust and running a new hot line direct to the horn with fuse and relay. Thanks again

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