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P0AA6, high resistance

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by K Hughes, Aug 24, 2021.

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  1. K Hughes

    K Hughes New Member

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    I would like to share a problem and the repair I had on my 2006 Prius.
    I was not able to find anyone that had this same problem so I was on my own to diagnose and repair it.

    My Prius keep triggering the code P0AA6. This code allowed me to drive the car but after stopping the code would not allow me to start the car. I would have to reset to codes to start the car.
    Using the Dr Prius app I could see I had high resistance in block 10. This block is connected to the orange safety service switch. I did physically see corrosion on the cables and tried to clean them the best I could but still had high resistance. I was forced to replace the cables. After removing the cables from the car I peeled back the insulation and found the corrosion on one of the cables had run most of its length.
    The Toyota dealers do sell this cable assembly. g3830-47050 for $18.41
    Installing the new cable solved this frustrating problem.
     
    #1 K Hughes, Aug 24, 2021
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  2. SFO

    SFO Senior Member

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    Welcome to PriusChat!!

    Thank you for sharing, and please continue to do so in the future.

    Here is an poor quality image of the part that was replaced :

    [​IMG]
     
    #2 SFO, Aug 24, 2021
  3. ChapmanF

    ChapmanF Senior Member

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    Congratulations on getting to the solution.

    The code you had, P0AA6, is a code about failing insulation, leading to unintended current paths,

    It isn't a code about high resistance on any intended current paths. Ordinarily your Dr. Prius resistance reading would not be any help to speak of when tracking down a P0AA6 issue.

    In this case, it led you to a short cable segment that apparently was the source of both your P0AA6 insulation leakage code and your Dr. Prius resistance reading. Not everyone can count on that kind of luck, but it's nice when it happens.

    For most people looking at a P0AA6, the quickest way to a solution will be to go straight to checking for insulation leakage. It is very helpful to start by using a scan tool that can read the INF codes that go along with P0AA6. Those will narrow the search into one of five different areas of the car. Four out of the five aren't even in the battery, so knowing which area to look in can help save some effort spent where it's not needed.
     
    #3 ChapmanF, Aug 24, 2021
  4. TMR-JWAP

    TMR-JWAP Senior Member

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    I would venture the cable is just ...a cable...and unfortunately (or is it fortunately?) working on the battery actually interrupted or changed the leakage path enough that it's not currently triggering the threshold. I would surmise there's about a 99% chance that code comes back though...

    hunt down a copy of techstream and take a look on the hybrid live screen and see what reading you have for shortwave highest value. That will tell you if the problem is resolved or is just lurking. It displays as a 0-5 volt signal. The majority of cars with insulation in good condition will show 4.99v. If there's an insulation problem the voltage will be lower. Code triggers around 3.2v if I remember correctly.
     
    #4 TMR-JWAP, Aug 24, 2021
  5. ChapmanF

    ChapmanF Senior Member

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    From what was seen on the replaced cable after peeling back its insulation, I can see at least a possibility that it was also the source of the P0AA6. But I agree it's a very lucky coincidence if so. Yes, the P0AA6 could return.
     
    #5 ChapmanF, Aug 24, 2021
  6. K Hughes

    K Hughes New Member

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    Originally I had code P3020 pop up, which points to module 10. That is why I started to inspect the cables to the service switch. I had recently reconditioned my HV battery pack and from my spreadsheet I knew module 10 should be in great shape. At that time I was unsure if the cables were bad and like I mentioned I could not find any information on why I might be having a problem. The code P3020 did allow me to drive the car. Before I could inspect the HV battery pack the code did change to P0AA6. I will update after driving for a few weeks to see if all problems are cured with the cable replacement
     
    #6 K Hughes, Aug 25, 2021
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  7. TMR-JWAP

    TMR-JWAP Senior Member

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    A P0A80 code (replace hybrid battery) should allow the car to continue normal operation. Once it codes due to a specific "module x becomes weak" (like the P3020) then the car will go to limp mode, and becomes marginally drivable.
     
    #7 TMR-JWAP, Aug 26, 2021
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