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2012 Toyota Prius Hybrid System Problems

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Clexy, May 21, 2024.

  1. Clexy

    Clexy New Member

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    May 20, 2024
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    Location:
    Lake Elsinore, California
    Vehicle:
    2012 Prius
    Model:
    Four
    Hi! I have a 2012 Toyota Prius and I was on the way home when it gave me the warning “Check the Hybrid System” and the engine light turned on and the exclamation warning sign and it automatically stopped driving. I had to tow it back home because it wouldn't start. Now, it is able to start but it gives me the same warning and symbols. I used a code reader and there were multiple codes that popped up.
    - Code P2102: Throttle Actuator Control Motor Circuit Low
    - Code P0A0D: High Voltage system interlock circuit high
    - Code P0A0F: Engine failed to start
    - Code U029A: Lost communication with hybrid battery pack sensor module
    - Code B2784: Antenna Coil circuit open/short

    The battery is full charged and the orange safety switch is correctly placed. I’ve looked at multiple threads and articles and youtube videos but I can’t seem to find the solution to fix the car. Is anyone able to help me?
     

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  2. Mendel Leisk

    Mendel Leisk Senior Member

    Joined:
    Oct 17, 2010
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    Location:
    Greater Vancouver, British Columbia, Canada
    Vehicle:
    2010 Prius
    Model:
    Touring
    Try dr Prius , a phone app for hybrid battery assessment. It requires an OBD port dongle; Carista works well. Just do the static test, and post a screenshot.

    it’ll look like this:

    IMG_4209.jpeg
    App is $10~20 IIRC.
     
  3. ChapmanF

    ChapmanF Senior Member

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    Location:
    Indiana, USA
    Vehicle:
    2010 Prius
    Model:
    IV
    99 and 44/100ths percent of the time, people who have P0A0D and say "the orange safety switch is correctly placed" simply haven't completed the last step of placing it, where the handle slides sideways to engage the small contacts in the safety interlock circuit.

    The other 56/100ths percent of the time, there's still a P0A0D even when that handle is definitely slid over and its small contacts are definitely engaged. In that case, the safety interlock circuit is open somewhere else. Its wiring runs from ground point S1 (high on the right quarter panel) through the safety contacts at the battery, toward the front of the car, through other safety contacts under cover panel(s) on the inverter, to the power management control ECU that reads its status. It passes through a handful of wire-harness-to-wire-harness connectors and junction connectors on the way. It is a dead-simple series circuit, so that an open anywhere along it will give a P0A0D code. There are no skills beyond basic diagram reading and multimeter use needed to attack it.

    The P0A0F is a report of the engine not providing power when expected, probably because of the throttle actuator code.
     
  4. Clexy

    Clexy New Member

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    May 20, 2024
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    Location:
    Lake Elsinore, California
    Vehicle:
    2012 Prius
    Model:
    Four
    Update: The P0A0D code is gone. Now it’s only the P2102 and P0A0F that is showing up. Does anyone know how to fix the P2102 code?
     
  5. bisco

    bisco cookie crumbler

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    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base