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Aaagghhh!! P0A78 & P0A94

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Don402, Nov 22, 2020.

  1. Don402

    Don402 Member

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    I was driving and all of a sudden CEL lights lit up all over the dash. Power diminished for a little bit too. Got off the interstate and drove back home on smaller streets.

    Got these codes: P0A78 & P0A94

    Just starting my research now, but would be thankful for suggestions and trouble shooting tips.

    I also have been having the noise in the video.(Not sure if the noise can be heard. Might need loud speakers.)
     
    #1 Don402, Nov 22, 2020
  2. PriusHead05

    PriusHead05 Member

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    Those two codes sounds like it lead to a bad inverter or bad wiring to the inverter.

    Posted via the PriusChat mobile app.
     
    #2 PriusHead05, Nov 22, 2020
    Don402 likes this.
  3. Don402

    Don402 Member

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    Would a bad wire be obvious? Signs of scorching? Is there a way to test the inverter?

    I forgot to mention, when I went to get the codes all the CEL light were gone. Car was running like nothing ever happened.

    Posted via the PriusChat mobile app.
     
    #3 Don402, Nov 22, 2020
  4. PriusHead05

    PriusHead05 Member

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    Wires: maybe or maybe not. Most of them have a shield on them so you might not be able to tell.

    If it went away, then it may have gone back to normal temporarily. It was probably the sign of a future problem. The codes are stored in the computer as history codes.

    Posted via the PriusChat mobile app.
     
    #4 PriusHead05, Nov 23, 2020
  5. dolj

    dolj Senior Member

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    Both of those codes have many sub-codes that will help narrow down the trouble area. The next time they flag, get the sub-codes. You will need to have a good scanner that can read freeze frame data to get the sub-codes.
     
    #5 dolj, Nov 24, 2020
    SFO likes this.
  6. Don402

    Don402 Member

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    Do MFD codes mean anything? Will I need to go to a dealership to get the sub-codes?

    Here's what my MFD listed:
    01-DA 1F1-97-1
    01-DA 440-97-1
    01-D8 190-29-1
    01-D5 190-74-F
    01-DA 178-19-1
    01-DB 178-EB-F
     
    #6 Don402, Nov 27, 2020
  7. dolj

    dolj Senior Member

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    Yes, they do but only relating to AV, Nav, and Gateway areas of the system.

    The above all look like communications errors.

    See the attached PDF for more details. Look at page AV-39 ff for diagnosing, paying attention to where they advise clearing the codes and then rescanning.

    For complete information you should look at the repair manual; more info.)
     
    #7 dolj, Nov 28, 2020
  8. Don402

    Don402 Member

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    I went and bought a used inverter. Question I have now is how do I know if it's the pump?

    Posted via the PriusChat mobile app.
     
    #8 Don402, Dec 4, 2020
  9. Don402

    Don402 Member

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    Okay, did some more research and look at my Prius again. I hear the pump running.

    Guess I'll go ahead with the inverter swap. Only paid $100 and have a 90 day gaurentee.

    Posted via the PriusChat mobile app.
     
    #9 Don402, Dec 4, 2020
  10. Priusdriver06

    Priusdriver06 New Member

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    Did that fix your problem swapping out the inverter?
     
    #10 Priusdriver06, Apr 11, 2024
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