ECU removal / replacement - 3rd Gen Prius

Discussion in 'Gen 3 Prius Technical Discussion' started by DieselHammer, Jan 30, 2025 at 8:45 PM.

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  1. DieselHammer

    DieselHammer Junior Member

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    Beyond getting to the ECU behind the glove box does anyone have instructions on removal?

    Many thanks in advance for your reply.
     
    #1 DieselHammer, Jan 30, 2025 at 8:45 PM
  2. ChapmanF

    ChapmanF Senior Member

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    There's a whole little village of ECUs behind the glove box. Which one do you want to remove/replace?
     
    #2 ChapmanF, Jan 30, 2025 at 9:19 PM
  3. DieselHammer

    DieselHammer Junior Member

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    Power Management Control part # 89681-47181

    Going through service manual for codes P0031 and P0032

    I have 12V on pin 2 of O2 sensor harness. Getting no continuity to the other three pins or ground. I’m at the step the service manual says replace ECU.

    I have 283000-1180 available.

    showing as not compatible.

    Trying to get CEL to stay out. Clearing codes they return in 30 sec or so.

    Might give it a temporary try to see if P0031 and P0032 are remedied. I’ll replace with correct ECU if this works.

    Thoughts?
     
    #3 DieselHammer, Jan 30, 2025 at 10:09 PM
  4. DieselHammer

    DieselHammer Junior Member

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    I carefully managed getting it out.

    Power Management Control part # 89681-47181

    Going through service manual for codes P0031 and P0032

    I have 12V on pin 2 of O2 sensor harness. Getting no continuity to the other three pins or ground. I’m at the step the service manual says replace ECU.

    I have 283000-1180 available.

    showing as not compatible.

    Trying to get CEL to stay out. Clearing codes they return in 30 sec or so.

    Might give it a temporary try to see if P0031 and P0032 are remedied. I’ll replace with correct ECU if this works.

    Thoughts?
     
    #4 DieselHammer, Jan 30, 2025 at 10:09 PM
  5. ChapmanF

    ChapmanF Senior Member

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    I'm pretty sure both O₂ sensors are connected to, and related trouble codes are set by, the engine control module (ECM), located out under the hood beside the fusebox.
     
    #5 ChapmanF, Jan 30, 2025 at 10:18 PM
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  6. DieselHammer

    DieselHammer Junior Member

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    Are you thinking of the Integration #2 Relay in the fuse box? Long white(ish) flat box.

    The Power Management Control part is what I was thinking was the ECU.

    From your message they appear to be two different parts.
     
    #6 DieselHammer, Jan 30, 2025 at 10:25 PM
  7. ChapmanF

    ChapmanF Senior Member

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    An ECU, or electronic control unit, is like a small computer responsible for some area of the car. A 2014 Prius has around two dozen ECUs, controlling things from the airbags to the power steering to the heating/air conditioning. There is even one ECU whose whole job is moving the little pawl in the transmission that keeps the car from rolling in Park.

    The one ECU that's responsible for the engine also has a name of its own, engine control module (ECM). It is located beside the fusebox under the hood (not in the fusebox, like the integration relay you're thinking of). It has two large multiterminal connectors plugged into it from the top.
     
    #7 ChapmanF, Jan 31, 2025 at 8:52 AM
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