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2008 Prius P0AA6 526 only on startup

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Jmotts, Jul 23, 2022.

  1. Jmotts

    Jmotts Junior Member

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    Does anyone know how to get the next subcode after P0AA6 526 on tech stream? I've tried clearing it and then driving to wait until it codes again but after like a 300 mile drive it doesn't even code again. But then if I shut off the car, it codes again P0AA6 526 upon startup. If I don't clear the code on startup, then after I shut it off, it wont go into ready mode anymore.

    During the 300 mile drive, I'll have AC on and all that and it still wont give codes.

    Any help is appreciated. Thanks.
     
    #1 Jmotts, Jul 23, 2022
  2. mr_guy_mann

    mr_guy_mann Senior Member

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    So, the ecu sets the P0AA6-526 the first time it detects that something might be off. The next time it tries to ready up and it sees a problem THEN it should set the additional INF code & disable the car.

    So, once you have the 526, shut it off , try to go ready, and when it won't, try checking for any other INF codes.

    Posted via the PriusChat mobile app.
     
    #2 mr_guy_mann, Jul 23, 2022
    bisco likes this.
  3. Jmotts

    Jmotts Junior Member

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    Thank for the help! That worked and I got code 614
     
    #3 Jmotts, Jul 23, 2022
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  4. bisco

    bisco cookie crumbler

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    #4 bisco, Jul 23, 2022
  5. ChapmanF

    ChapmanF Senior Member

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    Here's that:

    [​IMG]

    So you can see 614 covers the "high-voltage DC area", stretching from the load sides of the system main relays, through the frame wire under the car, through the DC bus portions of the MG inverter and the A/C inverter.
     
    #5 ChapmanF, Jul 23, 2022
  6. Jmotts

    Jmotts Junior Member

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    Story behind the car.
    2008 Used, 212k miles, Refurb battery 3/21/21. Drove to 252k miles without issue.

    Drive belt snapped earlier this year on the way to one of my destinations. Shut off car immediately and had it towed to dealer for a water pump, belt, and pulley replacement.

    From then on, other problems started. Car didn't even have power when I got it back. Dealer drained my 12v auxiliary battery down to like 6.7v, luckily I got a replacement same day.

    Started having the Red triangle light on the dash which never happened before, HV battery monitor on display was always going down to purple immediately when starting the car to ready mode.

    Been lurking forums for a year or so now, so with information, found a prius in a city a while away from me and picked up their HV battery to swap it into the car. Worked fine for like a week and it was always blue as normal but then it threw code again. Initially, thought it was inverter water pump so I had it replaced, and I do see turbulence and can feel the coolant flowing if I touch the hose but the light remains on.

    Now, it's been months of reading these forums and I still cant figure out the issue with the code. Really makes me wonder what the dealership did to my car!

    If its P0AA6-526-614, I'm thinking the inverter, but the car drives fine if I clear the code like the HV battery still charges up and gets used normally as well. Like wouldn't the HV battery not charge if the inverter as bad? I just can't understand it!

    Facts so far:
    Clearing code to do a reset, allows car to start to ready. Once in ready, car throws code immediately.
    Clearing code then, makes car drive normally, code doesn't throw code with AC on full blast, or shifting into D, R, P, etc, also doesn't throw code on long distance drives and battery doesn't turn purple.

    I've also tried unplugging the AC at the orange cable near the inverter and I still have the same code

    But then after shutting off car, attempting to turn it back on, car doesn't go to ready anymore and throws code.

    Any other suggestions guys? I can't really think of anything else. I did clean off the bus bars and the nuts already as well . Thanks
     
    #6 Jmotts, Jul 23, 2022
    Last edited: Jul 23, 2022
  7. mr_guy_mann

    mr_guy_mann Senior Member

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    Your are dealing with an isolation fault. Normally, there is no direct connection between the HV electrical system and the chassis ( low / 12V) system. If there is something "bridging" the two systems, that's a safety concern - and there is seldom any noticeable effect on operation.

    So, the ecu has detected something- after it turned on the HV contactors but before it tried to power up either MG1, MG2, or the A/C.

    A bad inverter is likely, but you should go through the 614 diagnostic procedures before loading up the parts cannon.

    Posted via the PriusChat mobile app.
     
    #7 mr_guy_mann, Jul 23, 2022
  8. Jmotts

    Jmotts Junior Member

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    Next update, swapped inverter anyways, kinda knew it wasn't inverter due to the 12v being 14v+ when ready but just wanted more confidence. Same issue with other working inverter. Guess it's the frame wire then. Luckily I have another prius I got free to take parts from...
     
    #8 Jmotts, Jul 29, 2022
  9. ChapmanF

    ChapmanF Senior Member

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    Be sure you check everything enclosed in the dashed-line box for code 614 in the diagram up there in post #5. The troubleshooting steps for 614 are a good way to do that. Notice that box encloses more than just the inverter and the frame wire.

    mr_guy_mann kind of touched on this, but it bears repeating: a component can have one kind of problem without having to have some other kind of problem at the same time. Having 14v+ out of the DC/DC converter tells you that the DC/DC converter hasn't stopped producing output. That's great, but it's got nothing to do with whether there is an isolation fault on the HV DC bus.
     
    #9 ChapmanF, Jul 29, 2022
  10. TMR-JWAP

    TMR-JWAP Senior Member

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    Just want to point out the obvious.....

    The last thing that was screwed with prior to having problems with was the HV battery. There's some funny looking orange cables connected to that thing, along with some shielding, a grounding strap, a current limiting resister, some other small wires, relays, etc..etc.....maybe one would benefit from inspecting that stuff...
     
    #10 TMR-JWAP, Jul 29, 2022
  11. mr_guy_mann

    mr_guy_mann Senior Member

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    I would expect a wire frame or battery ecu fault to set a 612, not a 614. If changing the inverter didn't help, then you should look at the contactors, and HV cables. As suggested- go back to "the scene of the crime" - check over the things that were messed with when working on the battery.

    Posted via the PriusChat mobile app.
     
    #11 mr_guy_mann, Jul 29, 2022
  12. ChapmanF

    ChapmanF Senior Member

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    A close look at the diagram shows everything from the load-side terminals of the system main relays, including the precharge resistor and the frame wire, are in the 614 box. Terminals on the modules side of the main relays fall in the 612 box.
     
    #12 ChapmanF, Jul 29, 2022
  13. Jmotts

    Jmotts Junior Member

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    Finally figured out the issues. The HV wires that leave the case were just barely touching it so that was why it sensed that ground path and tossed code. Nothing to do with HV battery OR inverter.
     
    #13 Jmotts, May 24, 2023
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  14. TMR-JWAP

    TMR-JWAP Senior Member

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    HV cables touching the case should not be possible unless the case is damaged.....or are you talking about the grounding connection on the cable shields, which is supposed to make firm contact with the case when assembled?
     
    #14 TMR-JWAP, May 24, 2023
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