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2008 Horn Relay Location PLEASE

Discussion in 'Gen 2 Prius Technical Discussion' started by CWB, May 7, 2022.

  1. CWB

    CWB Junior Member

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    I have searched here, I have searched reddit, I have searched Youtube.

    I can NOT FIND THE RELAY. Can someone post a pic or a video showing it's exact location. If not, don't reply with text.. I have tried and tried and I just can't find it. I looked at the fuse box and relay box on my 07 and tried pulling things one at a time and the horn beeps every time so I know it is none of them.

    I am at my wits end... please, anyone?
     
    #1 CWB, May 7, 2022
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  2. ChapmanF

    ChapmanF Senior Member

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    Could that be because you think you're looking for a single relay, and not the four-relay-fuse integration unit C unit B unit-with-the-fuses-in-it?

    [​IMG]
     
    #2 ChapmanF, May 7, 2022
    Last edited: May 7, 2022
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  3. CWB

    CWB Junior Member

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    Wait... are you saying that black rectangle the holds the four fuses IS the relay? I posted when I re-read your message and Im like..wqaaaaait a min

    MAJOR EDIT; That was it! Horn is working. The relay had gone bad. What frustrates me is every video, photo, post I read.. even though I read C... nothing directed me by saying "The four fuses, including the 10am horn, are plugged INTO a rectangular relay that could go bad."

    ... So I thank you for clarifying and giving me a spark to understand that the fuses are IN a relay... :)
     
    #3 CWB, May 7, 2022
    Last edited: May 7, 2022
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  4. ChapmanF

    ChapmanF Senior Member

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    It's an integration unit with four fuses and four relays.

    ubcin.png

    There's also a bit of weirdness, in that the one with the horn fuse and relay is called "unit B" in the wiring diagram (in all the places), and the diagram calls "unit C" the one next to it with the blank fuse fillers, but in some pictures it looks like the units really have letters B or C on them, the other way around.

    uabc.png
     
    #4 ChapmanF, May 7, 2022
  5. CWB

    CWB Junior Member

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    I wonder if it's due to the fact that B and C are identical and if, and I didn't test this, the wiring to them is long enough, B and C were supposed to be in the opposite slots. It was incredibly confusing as most all the material I read, watched and viewed via google images, never clarified that the relay was a long rectangular piece in the Gen 2. Even looking up replacement parts showed a black or grey or even blue Square box 'relay' with 4 teeth,,, nothing like the unit C, at all.

    Youtube videos, even when typing 2008 Toyota Prius Horn relay... I'd get vids of 2010's.. or later, or COROLAS... it was getting extremely frustrating.
     
    #5 CWB, May 7, 2022
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  6. ChapmanF

    ChapmanF Senior Member

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    The two parts are not identical, though; they have different part numbers, and when you compare their inner circuits above, there are differences (like the diode built into unit C but not unit B, which relays have a coil end commoned to the contact, and so on).

    It just seems to be One Of Those Things.
     
    #6 ChapmanF, May 8, 2022
  7. HIPriusHono

    HIPriusHono New Member

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    THANK YOU for this, the best thread on the internet on this frustrating topic!!!
    I finally understand where the horn relay is now (my 2007 horn just stopped working) thanks ONLY to you guys.

    However, when I try to pull out the C box, all the relay wires undernear are too tight to remove the box. SO how do you get the C box out to replace the horn relay please? I am worried that if I remove the wires to the 4 relays to get the box out, I won't be able to put them back in....

    THANK YOU!
     
    #7 HIPriusHono, Jan 31, 2024
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