2008 Prius purchased used - battery wiring problem????

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Silly_me, Jul 8, 2020.

  1. Silly_me

    Silly_me New Member

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    We bought a used 2008 Prius a few weeks ago from a guy who owns a smog place. He showed us the code reader before purchase - no codes - clean smog. Had the car checked by our mechanic - also checked out clean - no codes.

    Husband was driving the car about 120 miles round trip to work daily. A week in, the car dies on the freeway 2 miles from the house. All the lights come on (including the triangle of death). We have it towed to an independent shop who specializes in Toyota and was recommended by a local PriusChat member. Code: bad inverter. We get an inverter from a salvage yard and the shop installs. Car appears to be fixed on a test run. No codes.

    We pick the car up, 2 miles from the shop - all the lights come on again. Take it back to the shop, leave it another day with an estimate of $600 to examine the wiring to the battery, thought to be the issue. After 6 hours, they find no problem with the wiring. Super, super nice guys did not charge us a dime for the 5 hours. Feel really bad. They tell us we have to take it to Toyota.

    Toyota checks - says its wiring. They need to take car apart and examine wiring - it will be $600.

    Original mechanic said the battery is not the original and clearly not a great replacement, but the battery is not testing dead. Mechanic says it has a replaced (refurb) transmission too. Said its a pretty junked car (looks nice on the outside)

    What should we do? Pay the $600 to Toyota or just walk away from this loss? Could the wiring issue be part of the inverter install?

    CODE: DTC P0AA6 Is that the right way to put it?

    Hope someone can advise me.....
     
    #1 Silly_me, Jul 8, 2020
  2. TMR-JWAP

    TMR-JWAP Senior Member

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    A P0AA6 code is telling you there is a high voltage isolation fault. There are several different subcodes to let you know what area of the car the ecu thinks is the problem. Most often, it's due to the HV battery leaking a bit of electrolyte, which eventually makes contact with the battery case. I'm currently helping someone local with that problem.

    The HV system is totally isolated from the rest of the car. If anything happens to that insulation/isolation, it will trigger the P0AA6 code, with a subcode. This could be the HVbattery, the wires that connect the battery to the inverter, the inverter itself, the AC compressor or the transaxle.

    Once this code triggers, it will allow you to continue driving the car, but once you shut the car off, it will not let it go ready again. You can bypass this by disconnecting the 12v battery for a few moments. That will reset the ecu's and they'll forget about the code, allowing you to use the car again until (or if) the code triggers again.

    If any of your 'mechanics' have Toyota Techstream software, they can look at the Hybrid System Live screen and get the Short Wave Highest Value reading. Perfect isolation provides a 5.00 volt reading. I've never seen 5.0, most cars in good condition show 4.99 volts. The car I'm currently helping with was a 2.77 volt. The code triggers around 3.2ish volts if I remember correctly.

    If you reset this by disconnecting the 12v battery, and it still will not let you go ready, then there is a significant isolation fault in the battery itself.

    I'm really surprised the inverter was jumped on that quick, unless the mechanic did some good troubleshooting. That's kind of rare.
     
    #2 TMR-JWAP, Jul 8, 2020
    Last edited: Jul 8, 2020
  3. Montgomery

    Montgomery Senior Member

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    Well, I don't have mechanical experience with the Prius, but, after reading so many posts about this situation, here is my 2 cents.The car is 12 years old. If it has the original hybrid battery, thats a problem. If the car has a used, remanufactured, or "balanced" replacement hybrid battery, thats a problem. Either one of those situations means your hybrid battery is failing and you need a new one. Thats my simple read. However, there will be plenty of advice forthcoming your way..........with more details than I can provide from more talented and seasoned Prius chat members with vast experience in regards to your scenario.
     
    #3 Montgomery, Jul 8, 2020
  4. ChapmanF

    ChapmanF Senior Member

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    As we know it's a P0AA6, it wouldn't be unreasonable to go ahead and read the subcodes. The first time P0AA6 comes up there should be a subcode 526, and if that is left alone and not cleared, the car should do extra tests on the next startup and add a 611, 612, 613, or 614 to that.

    Those would indicate whether the isolation fault is in an easy or a hard place to fix.
     
    #4 ChapmanF, Jul 8, 2020
  5. Silly_me

    Silly_me New Member

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    Thank you all for your responses - all good ones!

    Here's an update - the diagnostician at the Toyota dealership we took the car to has many years of experience and purportedly recently won a Toyota award for the best in diagnostics in So Cal. (I can't find anything on google to support this) and evidently knows the Prius inside and out

    I asked for the sub-codes - the service advisor did not tell me. Not sure if he's being secretive or just didn't ask the technician. He only said the codes are not giving the answer, and the only way to find it is to literally test the wiring throughout the whole car.

    Battery - NOT the original - looks to have had cells replaced as needed and most likely the problem. But battery tests strong.

    Transmission - NOT the original - possibly the fix the guy did to turn the car over and possibly not installed correctly.

    Considered just getting a 5 year warranty refurbished battery - but there is NO GUARANTEE this will fix the problem as the wiring issue may be somewhere else.

    Remember - the car drove 120 miles round trip for 4 days.

    LONG conversation with the service manager about possibilities. We made it clear we are not installing a new $3K battery - the car is not worth it. Then we discussed the possibility of using the car as a trade -in on a used Prius on their lot. Basically - even the dealer is afraid of the rat hole of problems this car may contain. There are just too many possibilities - he admitted that they could not give us much for it because they don't know that they can fix it for a reasonable price - so that told us a lot.

    So - we are cutting our losses and walking away from it. The dealer will give us a few hundred if we buy a car on their lot.

    Sad story - and I'm never buying a Prius from a private owner again - never thought it was a good idea to start with.
     
    #5 Silly_me, Jul 9, 2020
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  6. TMR-JWAP

    TMR-JWAP Senior Member

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    They are hook, line and sinkering you......wish I was closer to help.
    There's probably a thousand people in Ca that would give you 1k + for the car as is. The exhaust system alone would sell for 1200 bucks out there.
     
    #6 TMR-JWAP, Jul 9, 2020
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  7. Silly_me

    Silly_me New Member

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    @TMR-JWAP I am aware of the exhaust system value and we did mention that to Toyota, but they responded they are "not a salvage yard" so through their access lines the car has no value. Not sure how true that is, but we were in no position to argue.

    I have a salvage contact we've used before and I did request a bid on the car, but they offered less than Toyota and certainly less than $1,400. I guess you'd have to know someone in the the salvage market to get a decent price.

    Good news is that we got a 2015 at a reduced price of $12,500 from the dealer - Toyota Certified with 88K miles in Charcoal Grey - a really nice color for my husband, and with really great tinting on the windows. So the world helped us out a bit.
     
    #7 Silly_me, Jul 13, 2020
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  8. bisco

    bisco cookie crumbler

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    cut the converter out before someone else does
     
    #8 bisco, Jul 14, 2020
  9. TMR-JWAP

    TMR-JWAP Senior Member

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    That sounds like a really decent deal on the 2015. Glad that worked out. Did you keep the Gen 2? If so, throw that thing on Craigslist and it'll be gone in a few hours for $1k or so. If you were closer to me, I'd be all over it.
     
    #9 TMR-JWAP, Jul 16, 2020
  10. Silly_me

    Silly_me New Member

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    I wish I could have, but time was such a factor. Both my husband and I lost several work hours that we couldn't really afford to lose just over the breakdowns, etc. The dealership gave us $800 for it and not a minute more lost.
     
    #10 Silly_me, Jul 16, 2020
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