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2009 horn is stuck

Discussion in 'Gen 2 Prius Technical Discussion' started by Freesky77, Sep 10, 2024.

  1. Freesky77

    Freesky77 New Member

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    Hi there,
    it's been over a month and I'm still driving without the horn because it went stuck on and I couldn't fix it neither the mechanics in my area.

    To be more specific, the problem occurs every time I hit the horn switch on the steering wheel. It goes wild and loud and won't stop until I turn off the car or pull the fuse out.

    I went to a mechanic who told me to change the clock spring and or the relay integration and I did.
    the problem is still there and I live in a crowded area so the horn is essential.
     
  2. Tombukt2

    Tombukt2 Senior Member

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    Me personally I would be pulling the airbag off the middle of the steering wheel it's easy to do. You need to follow the precautions and removing the airbag it's the same for most vehicles probably going to want to have the power off want to be using plastic tools so we create no sparks blah blah blah The orange and black connectors on the back of the airbag steering pad horn button lift up and withdraw straight up there's a lock on the back of the orange part look carefully it lifts up and then the connector lifts off set that over on the floor on the passenger side I believe with the bag or the logo aimed to the floor or if you're that worried about it slide it under the seat if it was to go off it certainly not going to lift the seat off of its bolts but if it goes off while it's on the floor it could seriously hurt you We have never gotten one to blow up yet but use your safety thinking cap and then see what happens with that black wire that runs from the steering wheel harness to the lower portion and tang on the airbag module horn button. Does your horn button feel normal when you push it down or does it kind of stick when you have this off and unplugged then that little wire the black wire with the spade connector on it that's your horn button now you're holding in your hand You touch that to the center nut of the steering wheel the horn should honk then when you lift up that spade connector with your fingers from the center nut holding on the steering wheel the horn should stop Do it again touch it the horn goes off move it the horn stops again okay so that's working. When the metal tang is not touching any metal you have no horn when you touch it with your fingers to meddle and it grounds you have horn.? So something is wrong with the steering wheel springs on the center pad and airbag assembly see the springs on the four corners when it's flipped over you should be able to push those down and they don't stick or any funny business something seems to be wrong right in there. The key is is if you're horn works normally with you just touching the little silver metal spade on the end of the black wire If that works then your problem I would think would be ahead of that which would be the pad with the logo and the four springs
     
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  3. TMR-JWAP

    TMR-JWAP Senior Member

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    Make a test light that will plug into the horn plug and let the light be mounted somewhere it can be easily seen. Then you can do better troubleshooting without the horn making noise. Find out what making the light go out or turn on.
     
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  4. Freesky77

    Freesky77 New Member

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    thank you for your reply.
    after troubleshooting, I found out that the the horn relay (located in the relay integration) keeps engaged and won't turn off even though I replaced it with another one. ( I disconnected the horn cables and was able to hear the relay's clicking noise every time I press on the switch button).
    moreover, I noticed that the horn sometimes functions normally when I put the car on the ready mode (ign-on and this won't work if the car is fully running) but after turning off the car within 30 seconds, the horn gets stuck if engaged!
    could that indicate a weak 12v battery?

    thanks again.
     
  5. pasadena_commut

    pasadena_commut Senior Member

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    Bench test the relay. First measure the coil resistance between two pins. If that is in range, apply and remove 12V across those two pins while measuring the resistance between the other two pins. If you think the relay might be sticking do it a bunch of times, especially after holding 12V for a while.

    I had a horn once which would stick on. It was on a Tercel. Somehow the problem was internal to the horn, and tapping it with a hammer several times fixed it for the rest of the time I owned the car. Maybe on that vehicle the horn was always wired to 12V and the horn had developed an internal short from something loose inside, like a bit of metal?
     
  6. mr_guy_mann

    mr_guy_mann Senior Member

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    There's not much to this circuit. The switch at the steering wheel provides ground to the relay coil, which closes the contacts and supplies power to the horns. The only way for the relay to stay on is if that circuit (relay coil to switch) is somehow staying grounded.

    Step one is to verify that someone hasn't hacked in some type of aftermarket alarm system. I have seen lots of problems with those things as they get old. Look at the driver's underdash area for crimp connectors, scotch locks, zip ties or lots of electrical tape.

    Otherwise, you need to get the horn relay to act up then unplug whatever connector is at the steering column for the horn circuit.

    Posted via the PriusChat mobile app.
     
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