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P0824

Discussion in 'Gen 2 Prius Main Forum' started by lexidium, Oct 1, 2021.

  1. lexidium

    lexidium Active Member

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    Sometimes, when I'm zooming up the motorway, I get the triangle and techstream throws up p0824.
    When I'm round the town again, I cancel it and it stays off.
    I've looked at the fan and it's clean and there doesn't appear to be any corrosion on the wires so I thought I'd test the speeds in techstream: It runs ok on No 1 but as I advance it, the triangle pops up. it's as if it's not keen on running at the higher speeds.
    What makes it run faster and slower?
     
    #1 lexidium, Oct 1, 2021
  2. dolj

    dolj Senior Member

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    What did you use to get that code? Just asking because it does not appear to be a valid Prius Gen 2 code. Is it perhaps a mistyping of P0A84?
     
    #2 dolj, Oct 2, 2021
    Raytheeagle likes this.
  3. lexidium

    lexidium Active Member

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    Yes, sorry, p0A84.
    That's what happens when you start threads at 1.30 am :oops:
     
    #3 lexidium, Oct 2, 2021
  4. mr_guy_mann

    mr_guy_mann Senior Member

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    So, the HV battery ecu controls what the blower does. The ecu turns a relay on or off that supplies 14V to the (+) side of the blower. Then the ecu sends a variable squarewave signal (Pulse Width Modulated) to the blower controller- in essence a transistor that can adjust how much the (-) side of the blower is connected to ground. The ecu monitors that (-) circuit. When the blower is off there should be 14V on (-), at 50% on there should be 7V, at 100% on there should be near 0V, etc.

    That code indicates that the battery ecu saw a lower voltage on that (-) side monitor circuit (labeled VM on the diagram) than it expected. You should get a copy of the service manual with diagrams so you can start testing circuits with a multimeter. I might start by confirming that the (+) side stays at a steady 14V when controlling the blower with techstream.

    Posted via the PriusChat mobile app.
     
    #4 mr_guy_mann, Oct 2, 2021
  5. lexidium

    lexidium Active Member

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    Thanks for that.
    I've put the wiring diagrams for gen 2 in the file library now for anyone that wants it.
     
    #5 lexidium, Oct 2, 2021
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