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2008 Prius security issue (alarm won't engage + door locks)

Discussion in 'Gen 2 Prius Technical Discussion' started by Murban, May 16, 2023.

  1. Murban

    Murban New Member

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    Vehicle:
    2007 Prius
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    Premium
    I'm having a lock issue with a 2008 Prius.

    The doors will lock, but within an hour or two at the most the alarm starts going off. Everytime.
    When locking the red light on the dash with the key shape with blink/flicker. It's almost like there's a connection issue they won't allow the security system to engage completely.

    I've already changed the door handles without any difference made.


    Has anyone tried changing the security module or know where to locate it?

    Thanks in advance!
     
    #1 Murban, May 16, 2023
  2. Tombukt2

    Tombukt2 Senior Member

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    I think the alarm module is behind the rear passengers drink cup holder on the console when you pop that off you see the red and white module there and it has the frequency and alarm business all printed on top of it in red I think Red label white control square well rectangle.
     
    #2 Tombukt2, May 16, 2023
  3. dolj

    dolj Senior Member

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    That receiver is just for detecting the key is in the car, so that not going to help any. The immobiliser is somewhere buried deep in behind the dash, but I don't think that's you problem either.

    Does your car have factory (or port-side install by dealer) alarm or some aftermarket alarm installed?
     
    #3 dolj, May 17, 2023
  4. Murban

    Murban New Member

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    Thank you for taking the time.
    Just your standard factory alarm from Toyota...

    The keys have been changed.

    It is just your standard Toyota factory alarm...
     
    #4 Murban, May 17, 2023
    Last edited by a moderator: May 17, 2023
  5. Tombukt2

    Tombukt2 Senior Member

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    When you say the keys have been changed do you mean the black plastic immobilizer remotes?
     
    #5 Tombukt2, May 17, 2023
  6. mr_guy_mann

    mr_guy_mann Senior Member

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    The factory alarm system is a function of the body control ecu (BCM). It monitors a bunch of inputs, arms the system, and will trigger the alarm if an input indicates "tampering" (ie, a door switch has changed state).

    Unfortunately, the Gen2 BCM doesn't keep a record of what triggered the alarm.

    Option 1) if you don't care about the alarm (and just want it to not sound off), then try unplugging the hood latch switch. I think that should prevent the alarm from ever arming.

    2) if you want the system to work correctly, get a capable scantool to check BCM data. See if any hood, door or tailgate switches change while driving the car. Could be something like a fritzy tail hatch switch.

    Posted via the PriusChat mobile app.
     
    #6 mr_guy_mann, May 18, 2023
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