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Horn giving me a jolt

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  • Horn giving me a jolt

    My horn on my 62 was working fine for some time. Noticed on a few HOT weather drives in the last month it would honk a few times then nothing. Yesterday I got a few then nothing. So I pressed harder on the left side of horn (for no good reason) on steering wheel and got a little JOLT from it. I drove for a bit and hit it again and got another zap of electricity.
    This thing have a horn relay that needs replaced?
    Tim
    1962 Conv Tbird
    1993 Miata LE
    1994 Miata

  • #2
    The shock you are feeling is what we call, counter electromotive force (CEMF) or 'fly back'. It happens when the coil field is charged, then disconnected when the switch (your horn ring) opens. Magnetism quickly collapses back into the relay's iron core which induces a high voltage in the surrounding wires. This effect is exactly the same as what makes your ignition coil create a spark.

    Electricity takes the path of least resistance. If this flyback voltage cannot easily discharge, it will try a path through your steering wheel horn ring (to ground).

    If you connect a diode in reverse across the horn relay coil, that will re-direct any potential shock. By that what I mean is, connect the anode side of a diode (the band end) to the coil's + power terminal (on the LH side or yellow) and the cathode end of the diode to the middle terminal. The middle terminal should be your horn ring wire (blue-yellow). Check this against your wiring diagram.

    I would use an inexpensive diode like a 1N4007. If you can't find one right away I will mail you one. - Dave
    My latest project:
    CLICK HERE to see my custom hydraulic roller 390 FE build.

    "We've got to pause and ask ourselves: How much clean air do we need?"
    --Lee Iacocca

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    • #3
      cant just replace the horn relay?
      Tim
      1962 Conv Tbird
      1993 Miata LE
      1994 Miata

      Comment


      • #4
        I assume the horns are not working due to a bad relay?
        Tim
        1962 Conv Tbird
        1993 Miata LE
        1994 Miata

        Comment


        • #5
          ok, searched here of all places.
          I found the relay is below volt reg, simple enough.
          I saw an old post here about the steering column may have slipped down and that if I raise it that may be a fix. Something parts for the horn in the column out of alignment.
          Tim
          1962 Conv Tbird
          1993 Miata LE
          1994 Miata

          Comment


          • #6
            I thought the topic was about a jolt from the horn.

            If you want to troubleshoot the horns you can do it at the horn relay. Simply run a ground wire to the center terminal of the horn relay. A blue-yellow wire should be there.

            That should energize the horn relay which delivers +12-volts to the horns. Do your steering column troubleshooting after this test passes.

            When I troubleshoot a problem, the very last thing I ever want to hear is, "Last time it was..." Instead, follow sound troubleshooting practices (which will lead you straight to the problem). - Dave
            My latest project:
            CLICK HERE to see my custom hydraulic roller 390 FE build.

            "We've got to pause and ask ourselves: How much clean air do we need?"
            --Lee Iacocca

            Comment


            • #7
              It is about the horn. It worked, then seemed when I drove it I recently it would get a few honks then nothing. It has been hot, I have some exhaust manifold gaskets that are bad so I thought the excessive heat may have damaged a relay causing the new issue.
              Now yesterday I hit the horn and got a zp from the ring when I hit it. Not every time but a few times. I figured it would be the relay since it has one.
              Tim
              1962 Conv Tbird
              1993 Miata LE
              1994 Miata

              Comment


              • #8
                "If you want to troubleshoot the horns you can do it at the horn relay. Simply run a ground wire to the center terminal of the horn relay. A blue-yellow wire should be there."

                When I do that, the horns should go off? Or I go hit the horn n ring in the car and they go off with no jolt.
                Tim
                1962 Conv Tbird
                1993 Miata LE
                1994 Miata

                Comment


                • #9
                  Originally posted by blue62tbird View Post
                  When I do that, the horns should go off? Or I go hit the horn n ring in the car and they go off with no jolt.
                  The horns should blow, just the same as if you use the horn ring. This jumper wire bypasses wiring to your steering wheel. Refer to your wiring diagram.

                  The diode information will eliminate any jolt at the horn ring. - Dave
                  My latest project:
                  CLICK HERE to see my custom hydraulic roller 390 FE build.

                  "We've got to pause and ask ourselves: How much clean air do we need?"
                  --Lee Iacocca

                  Comment


                  • #10
                    Horn giving me a jolt

                    IF you do not have the wiring diagram for your Tbird, look in the Technical Resource Library (TRL). They are all there...

                    Ray Clark - Squarebirds Administrator
                    '59 Tbird "The Yellow Rose Of Texas" aka "Tweety Bird"
                    "It's Hip To Be Square"
                    Thunderbird Registry #33025 VTCI #11178

                    Contact me via Private Message for my email address, or (Cell) 210-875-1411 (Home) 210-674-5781

                    http://www.squarebirds.org/picture_gallery/TechnicalResourceLibrary/trl.htm

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