Techstream test of alarm horn goes click click click

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by pasadena_commut, Sep 24, 2021.

  1. pasadena_commut

    pasadena_commut Senior Member

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    Vehicle:
    2007 Prius
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    Today I tried to determine if there was an "alarm horn" in our 2007. Previously I had looked around where the diagrams indicated this horn should be and found nothing. Fired up techstream and ran the active test for it under "Body electrical" then "Body live". When set to on an audible "click click click" was heard, possibly from under the dash on the left, but it might have been in the engine compartment. But no horn. The clicking speed was at about the same rate as the emergency flashers - nothing lit up on the dash though.

    So does this model have a relay to fire this horn, but not the actual horn? My son has one of those signal tracing electrical gizmos, so if we can find this relay we may be able to find the other end of the wire it drives, and from there a horn could be added.

    Note, the active test for the "normal horn" works.

    Thanks.
     
    #1 pasadena_commut, Sep 24, 2021
  2. ChapmanF

    ChapmanF Senior Member

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    Sure sounds like that's your situation. And if you wanted to look in the wiring diagram (more info) you'd probably end up knowing the location, color, and terminal style of the other end of the wire, all in one step.
     
    #2 ChapmanF, Sep 24, 2021
  3. mr_guy_mann

    mr_guy_mann Senior Member

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    The manual for my 2006 shows a security horn somewhere on the right side of the firewall- behind the engine? Diagram shows a single yellow wire from the main body ecu to the security horn- no (external) relay.

    Posted via the PriusChat mobile app.
     
    #3 mr_guy_mann, Sep 24, 2021
  4. ChapmanF

    ChapmanF Senior Member

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    The body ECU and the instrument panel junction block are pretty much joined at the hip, and there are relays embedded for all time way inside the guts of that thing, as hobbit found.

    [​IMG]
     
    #4 ChapmanF, Sep 24, 2021
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