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Easiest way to run a new wire through firewall?

Discussion in 'Gen 3 Prius Technical Discussion' started by Seymour1, Sep 26, 2024.

  1. Seymour1

    Seymour1 Junior Member

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    I want to add a new horn but to use independately. I need a wire to go from a new horn button to the engine compartment. Any ideas?
    I once had a Camry that the weak horn operated normally unless I also had my foot on the brake petal. Then, the loud horn blew. I could select loud or soft.
     
  2. ChapmanF

    ChapmanF Senior Member

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  3. Seymour1

    Seymour1 Junior Member

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    Thank you. This is exactly what I was looking for.
    At first, I was a little confused by ebay commercials in between posts. The commercials looked highly technical
    but did not make sense.
     
  4. TNToy

    TNToy Member

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    This is easy to set up with a relay, for the record., using the factory horn button on the steering wheel. You’d only have to run a wire tied into the stop light switch (12v+ with brakes applied) into the engine bay.
     
  5. Seymour1

    Seymour1 Junior Member

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    That is how I did it on my Camry and plan to do on my Prius. But I still need to run a wire through the firewall. I doubt that the existing brake light wire goes in to the engine compartment.
     
  6. ASRDogman

    ASRDogman Senior Member

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    (n) So everytime they press the brake pedal the horn sounds? Nifty! :ROFLMAO::whistle:

     
  7. Seymour1

    Seymour1 Junior Member

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    No. Every time the horn blows, the brakes are applied.
    I connected one side of the new relay coil to the brake circuit (normally zero volts). I connected the other side to the anode of a 1 amp doide anode. The cathode connects to the horn button circuit. x
     
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  8. ChapmanF

    ChapmanF Senior Member

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    ¿ o_O ?
     
  9. Seymour1

    Seymour1 Junior Member

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    Chap- I was answering a prior post. I am trying to learn how to include the prior post with my answer.
     
  10. xliderider

    xliderider Senior Member

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    Click on the "quote" button on the post you want to quote. Then add your text after the quoted text.

    SM-G781V ?
     
  11. ChapmanF

    ChapmanF Senior Member

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    Me, I'm trying to figure out how a person would arrange for the brakes to be applied when the horn blows.
     
  12. Seymour1

    Seymour1 Junior Member

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  13. Seymour1

    Seymour1 Junior Member

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    I have to add a relay and a diode for it to work correctly.
     
  14. ChapmanF

    ChapmanF Senior Member

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    Are you thinking you'll do something electrical that will cause the brakes to be applied?
     
  15. TNToy

    TNToy Member

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    You need to learn more about how versatile relays can be.
     
  16. ASRDogman

    ASRDogman Senior Member

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    You need to learn and recognize a joke...

     
  17. ChapmanF

    ChapmanF Senior Member

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    pretty sure i've just recognized two
     
  18. Seymour1

    Seymour1 Junior Member

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    No. I was posting a (funny) reply to a post that asked if the horn will blow when the brakes are applied. I thought that the person was joking. I apologize.
    So, here is what I think will work. see attached drawing. The diode leads must be secured so that they do not flex due to vibration. I think the hardest part is running a wire through the rubber grommet in the firewall. It is hard to reach. IMG_2895.JPG
     
  19. ChapmanF

    ChapmanF Senior Member

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    Ah, ok, that makes sense.
     
  20. Seymour1

    Seymour1 Junior Member

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    It did strike me as funny if the horn would blow when touching the brake petal.