P0A09 - 12v DC Inverter low, but the 12v still charges -

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by FjDubs, Mar 8, 2022.

  1. FjDubs

    FjDubs New Member

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    Checked the voltage at the jump point using an inverter bolt for ground and it shows 14v

    Power distribution display does not show any arrows at all. Also noticed, in freeze frame data, that battery charge/discharge current is always at 0.

    Engine turns on now and then to charge the pack I assume. HVAC was off.

    12v should be healthy enough. After a few times powering up the car; the lowest reading was 11.8v. 4 other times; the reading was around 12.2v

    Gauge cluster shows a small yellow triangle along with a red 12v battery icon. Also the center of the screen displays check hybrid system.

    There are no other codes.

    Any input is greatly appreciated. I understand there is more info available online about the sensing circuit for gen 2. Gen 3 is visibly different. Also I would love to learn as much as possible about this.
     
    #1 FjDubs, Mar 8, 2022
  2. ChapmanF

    ChapmanF Senior Member

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    You're measuring 12 volt bus voltage, but that's not what the code you have is talking about. It's about an open or ground short in the NODD control circuit.

    nodd.png
     
    #2 ChapmanF, Mar 9, 2022
  3. FjDubs

    FjDubs New Member

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    The inverter has already been swapped and the code remained I believe. So they put the original inverter back in. Now the Power Management Control Ecu would be the only thing left to cause the code? Thats only after I can confirm continuity from pin 12 (a59) on inverter, to pin 21 (a21) on PMC ecu, along with no shorts to ground

    Also will check the 5 amp dc/dc-s fuse, along with checking for 12v making it to 11 (a59) on the inverter, since It will be disconnected.

    I will be taking another look at the car tomorrow. Does this sound like I am on the right track?
     
    #3 FjDubs, Mar 9, 2022
  4. FjDubs

    FjDubs New Member

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    Got my hands on a 2010 repair manual and started to follow the test procedures which led me to the connector on the left side of the inverter. There I found a broken red wire right where it disappeared under the wire wrapping. Fixed the wire and fixed the problem luckily.

    Now I have a 2012 Lexus CT200H with code C1391-Abnormal leak in accumulator, along with freeze fame, and live data images if anyone wants to help take a shot at diagnosing. The accumulator pump runs every 3 seconds for about 3 seconds at a time. Sound like an obvious accumulator replacement? No other codes
     
    #4 FjDubs, Mar 16, 2022
  5. ChapmanF

    ChapmanF Senior Member

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    If you could freeze fame we'd all get more than 15 minutes.

    No difficult diagnosis there. C1391 tells you what the problem is, and so does "every 3 seconds for about 3 seconds." You have an internal hydraulic fluid leak, and it is Niagara-level bad.

    However, this is not "obvious accumulator replacement", because a leak like that can be either in the accumulator (lower thing in this picture) or in the booster (upper thing). As things go, more often the problem is the upper thing. There are more little valves in it, so it has more chances to develop leaks.

    [​IMG]

    If you get your hands on a cheap mechanics' stethoscope, you can touch it to both of those things. During the three seconds between pump runs, you should hear a heckuva hissing sound in one of them.

    Have you thought of starting a new thread for this? People reading a thread about P0A09 and the inverter won't be expecting to read about brakes and C1391.
     
    #5 ChapmanF, Mar 16, 2022
    CR94 likes this.
  6. FjDubs

    FjDubs New Member

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    Lol! Whoops I meant frame


    So I believe I have searched and read one of your posts mentioning mentioning the cheapo stethoscope before taking a look, and I ended up showing up armed with one. However, I did not hear any hissing, or any noise whatsoever; after the loud pump would run. I probed both units, and even directly on one of the lines from brake booster assembly; heard nothing except when the pump would run.

    I will start another thread shortly, now that I jave heard the part number for the accumulator cross references with the gen 3.
     
    #6 FjDubs, Mar 17, 2022
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