2005 Red warning light - code P0AA6 - 526 & 612 also P0300, 301, 303

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Paul ter Brugge, Dec 24, 2014.

  1. Paul ter Brugge

    Paul ter Brugge New Member

    Joined:
    Dec 24, 2014
    2
    0
    0
    Location:
    Portland, Oregon
    Vehicle:
    2005 Prius
    Model:
    N/A
    Historical data; 2005 Prius purchased second hand with about 130k. Now about 135k
    We got in a fender bender, being hit by a semi moving slow in May or June this year. Lights first came on after that, bumper is slightly bulging out. Dealer said we needed to replace the 12 volt and couldn't find anything else.
    Around Thanksgiving lights came back on and car completely stalled. Towed to dealer, gave us the codes in the title. Sat at the shop for a Sunday and on Monday 12 volt needed to be charged, no codes available anymore. Dealer drove it a bit, yet no codes so either pull main battery apart to try and find a code or bring it back in when codes return. Drove it for a few weeks, warning light back on. Did some research here and other sources, found that unplugging the 12 volt would reset the system which it did yet as soon as I turn it off, it won't start again. So back to unplugging 12v and drive it with warning light. I also noticed there is some water under the 12v and likely under the main pack due to a leak somewhere. Possibly from the fender, Toyota dealer said that there was no water when they had it late November. Have taken it to another shop to get a second opinion, gave them dealer paperwork to avoid double work. They say the main battery needs to be replaced as it is overdue anyway. Claiming they last for 8 years, online I find people talking about batteries lasting for 300k. I am confused, the dealer wants to pull the battery apart to find the specific culprit. Another shop says to just get a new battery yet they are not sure that will resolve the issue. I read online somewhere that adding fuel injector could be helpful...
    I am concerned about spending $2,000 for a new battery to spend another few thousand on a new transmission or axle or whatever. Any knowledge or experience with any of this.
    Thanks. Much appreciated.
    Paul
     
  2. ericbecky

    ericbecky Hybrid Battery Hero

    Joined:
    Mar 12, 2004
    4,358
    3,164
    1
    Location:
    Madison, Wisconsin
    Vehicle:
    2005 Prius
    Model:
    Two
    Wait. I'm confused.
    Have you replaced the 12v battery yet?
    If so, when?

    Clearly it is weak if it couldn't even go a few days w/o being charged.

    Always start with testing/replacing a 12v if you are getting weird codes.
     
  3. Patrick Wong

    Patrick Wong DIY Enthusiast

    Joined:
    Mar 8, 2008
    18,181
    6,288
    0
    Location:
    Green Valley, AZ
    Vehicle:
    2015 Prius
    Model:
    Two
    I agree that the 12V battery needs to be replaced. However that is the least of your car's issues.

    The most important issue is that a high voltage ground fault exists. You need to find and eliminate the water leak. The most likely source of the leak is damage from your accident, or else a seam along the hatch opening.

    The ground fault is located within the traction battery case, hence your dealer recommendation that the battery case needs to be opened up for examination to determine the location of the ground fault. If the fault is due to water entry, maybe that can be fixed without incurring substantial expense.

    Further, your car has engine misfire codes for cylinders 1 and 3. The first thing I would do is to remove the spark igniters for those cylinders, to see whether any water moisture is in the spark plug wells. For example, if rust is evident on the spark igniter plastic body or the spark plug, that would be proof of water entry. In that case replace any igniters that show rust or cracking in the plastic body, as well as the iridium spark plugs.

    Sometimes water will drip down the center cowl seam onto the engine cylinder head. If a bead of black RTV sealant is placed on that center seam, that may help.

    Yes, some Prius (typically taxis) can log 300K miles in usage and the traction battery is fine. Other Prius will have a failed battery at a much lower odometer reading.
     
  4. Paul ter Brugge

    Paul ter Brugge New Member

    Joined:
    Dec 24, 2014
    2
    0
    0
    Location:
    Portland, Oregon
    Vehicle:
    2005 Prius
    Model:
    N/A
    First of all thanks for the responses!

    Just to clarify, I don't think I was very clear. The 12 volt was replaced in June. Things were fine for a couple months.

    Around Thanksgiving we started getting the warning signs again. Leading to a complete halt, a visit to the dealer where the car sat for a Sunday and started up without any repairs, just them pulling the codes. As there were no more codes, they returned it to us.
    Again, no issues for a few weeks until we got the warning sign again and car not starting after turning it off. My own research led me to learning disconnecting the 12 volt would reset the system. While driving there doesn't seem to be anything wrong; normal acceleration, car uses battery and engine, battery appears charged, similar mpg. Just as soon as you stop the system, it won't start. I read somewhere that this is a 'safety feature' due to some issue with the battery.

    I guess my question is why Toyota wouldn't know or share with me that this is a "well-known" issue for the 2nd generation prius. Also, why would the other shop tell me just to replace the battery as there could just a short or some water damage/ rust creating this error message. They say it is just due as the battery is over 8 years old.
    I am hesitant to believe either of them. I think 'going down the line' to find the culprit seems logical, yet it is the dealership and why they don't know about these error codes that a quick non mechanic like me can find lots of info on seems pretty odd. On the other hand, the smaller local shop says just replacing the battery for like 2k yet we can't say for sure this will resolve anything... also feels odd.

    Anybody have experience with replacing the battery and things running okay again? Or anybody have experience with 'ground fault' (thanks Patrick Wong) and finding a short or 'broken' connection that was a small fix?
    I appreciate all your insights and feedback. Thanks for being an awesome prius community that makes me feel less alone in this dilemma with my car.
    Best wishes for 2015.
    Paul
     
  5. bisco

    bisco cookie crumbler

    Joined:
    May 11, 2005
    95,319
    43,208
    0
    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    if you need a new hv battery, there should be a trouble code. i think you should test the health/charge of your 12v first. usually when the hv battery is going, you get some erratic behavior, not sure i've heard of the car not starting unless it's almost dead, but then, you should be at one purple bar.
     
  6. TampaPrius.com

    TampaPrius.com Active Member

    Joined:
    Feb 20, 2013
    457
    289
    0
    Location:
    Tampa, Florida
    Vehicle:
    2008 Prius
    Model:
    N/A
    You have several issues. The no start(won't go into ready mode) after the triangle comes on is the P0AA6 with subcodes 526 and 612 indicates a ground fault inside the hybrid battery pack. I have replaced two of these in the last 3 month and have had them sitting on the shelf for a while trying to figure out the problem with them.

    The cars worked perfectly after installing a different good hybrid battery pack.

    The packs I removed I tried to troubleshoot. I took them apart, inspected them thoroughly for electrolite leaks, cracks anything. They look perfect and perform perfect when monitoring on the scanner but through the P0AA6 and 612 codes and won't restart. I have tried replacing the computer, bus bars, case, resistors, basically every part of the battery individually but still get the code.

    I just found this info on iATN recently and will attempt to repair these packs:

    "Hey Prius techs! I'm in need of help! I have this Prius here with codes listed above. P0AA6 Hybrid battery isolation fault with inf codes 526 and 612. I Removed hybrid battery pack and found battery acid leak around the casing. Removed all battery cells and cleaned and painted the case. cleaned all batteries and checked for leakage, nothing significant found, installed everything back together.

    Cleared codes and started right up. Drove about 5 miles, the light comes back on with same code, but only 526 inf code. I double check everything I did, but looks perfectly fine visually. I cleared again, drove 2 blocks down and code pops up. This time with inf codes 526 and 612 back again. When these codes pop up, I can still drive it normally, only if I don't shut it off.

    I've tested the main relays, the main power and ground wires, and A/C compressor. The AC was never worked on this so I know it's got nd-11 on the system, plus it would have a different inf code for AC system leakage.

    If I follow the troubleshoot guide, it would only lead me to a bad HV ECU. But I don't want to replace it just because a paper is telling me to, I want real facts and test results. Please guide me to the right path guys! I'm stuck!

    Related Repair History

    Removed hybrid battery pack and found battery acid leak around the casing. Removed all battery cells and cleaned and painted the case. cleaned all batteries and checked for leakage, nothing significant found, installed everything back together

    Kevin ParkTechnicianIndependent Car SpecialistLos Alamitos, California, USA

    FIX posted on Aug 19, 2011 12:04:48 PM

    Ok guys. This car is fixed! I need to clear things up first. I was talking about the battery acid physically leaking out the batteries on to the case. I cleaned them, reinstall everything, and drove it for a day, until it happened again.

    I replaced 7 battery cells that were either leaking externally, or had a short to the case. I ended up buying a megohmmeter just for this and it works wonders! You GOTTA HAVE ONE! I put the setting to 500V test, and started testing each and every batter cell terminal looking for a short to bettery case. Sure enough, one battery was completely shorted to the case, causing the code to store. Replaced battery cells and all done! Drive like a charm with no codes or lights coming on!

    So for all the Technicians out there that are about to work on Priuses, you HAVE TO GO BUY A Megohmmeter. It works just like an ohmmeter but sends very high voltage to test the insulation and integrity of the circuit you're testing. I bought mine @ Fry's electronics for $180. Extech was the brand and it worked perfectly. Just becareful working with these high voltage systems because you will get fried! One bad move can stop your heart! Always wear special insulated glove and tools made to work with high voltages. (I know I did't either, but will be getting them soon)

    Special thanks to all the members that posted GREAT information! I hope in time this post will help other techs as well. Thanks guys!"


    I ordered a much cheaper megohmmeter from eBay
    BM500A 1000V LCD Digital Insulation Resistance Tester Megger Megohmmeter Em 01 | eBay

    I won't have it until approx January 7. I will update with my progress.


    Back to your problem...If you are not equipped to rebuild or repair your own battery I would recommend getting a new/used hybrid battery. The codes you have point to it as the problem. If you were closer to me I could install one for you and let you make sure that was the problem. If not return it for a refund. If you can find a local place to make you a similar offer that would be ideal.

    Your other P0300, P0301, P0303 misfire codes are an entirely different problem that you may need to figure out first.

    Some have installed a switch to the negative terminal of the 12V battery to reset the computer to be able to start the car after the P0AA6 code is set. This is not a permanent solution but can be handy until you figue out the misfire problem.
     
    Cody26 and koolingit like this.
  7. edthefox5

    edthefox5 Senior Member

    Joined:
    Jul 25, 2007
    9,496
    4,440
    0
    Location:
    Clearwater, Florida
    Vehicle:
    2007 Prius
    Model:
    Two
    Much faster way to boot the 12 volt is to remove the red plastic cover off of the positive terminal and you'll see a thick black wire that goes to a white plastic connector. Thats the 100 amp wire. There's a click tab on it. Compress the click tab and pull the wire out. There's also a smaller wire next to it the 5 amp line. Same deal compress and pull out. The 12 is now disconnected from the car.
    Then reseat the connectors till they click and the battery is booted not necessary to unbolt the neg on the chassis with all the sparking and tools.

    Toyota made it easy. Use it.
     
    John Gjata likes this.
  8. ericbecky

    ericbecky Hybrid Battery Hero

    Joined:
    Mar 12, 2004
    4,358
    3,164
    1
    Location:
    Madison, Wisconsin
    Vehicle:
    2005 Prius
    Model:
    Two
    Good ol' megger. Can't beat it as a diagnostic tool.
    I can guarantee you that the dealer is not going to take apart the pack.
    If there is a leak and the code is stored, then they will suggest replacing the pack if the fault is in the pack.
    An older pack is of course more likely to have this issue than a newer one. Not sure if that what the "it's due" comment was getting at?
    Anyway, keep us informed of your progress.
     
  9. TampaPrius.com

    TampaPrius.com Active Member

    Joined:
    Feb 20, 2013
    457
    289
    0
    Location:
    Tampa, Florida
    Vehicle:
    2008 Prius
    Model:
    N/A
    I received the megger but couldn't figure out how to use it. The instructions were useless.

    I removed all of the bus bars and just used a regular DVM and tested each terminal to chassis (bottom of case) until I found one module that was showing 6.71 V. I replaced that module. I am balancing and will put this battery in a car and drive it for a couple days to see if that takes care of it.
     
  10. Patrick Wong

    Patrick Wong DIY Enthusiast

    Joined:
    Mar 8, 2008
    18,181
    6,288
    0
    Location:
    Green Valley, AZ
    Vehicle:
    2015 Prius
    Model:
    Two
    The basic concept is that the merger is an ohmmeter which uses high voltage (instead of a sub-volt level) to determine resistance. Does that help at all?
     
  11. flyboy09

    flyboy09 Junior Member

    Joined:
    May 11, 2005
    56
    4
    0
    Location:
    Seymour Tennessee
    Vehicle:
    2005 Prius
    Model:
    N/A
    just wondering if you figured out how to work the megohmmeter? i just ordered one through amazon for my 2005.i am getting the triangle every time i drive it.
     
  12. ericbecky

    ericbecky Hybrid Battery Hero

    Joined:
    Mar 12, 2004
    4,358
    3,164
    1
    Location:
    Madison, Wisconsin
    Vehicle:
    2005 Prius
    Model:
    Two
    What are the latest trouble codes?
     
  13. strawbrad

    strawbrad http://minnesotahybridbatteries.com

    Joined:
    Aug 9, 2011
    924
    918
    0
    Location:
    Minnesota
    Vehicle:
    2005 Prius
    Model:
    II
    I have tracked down leaks in Gen I batteries. There is a ground found detection circuit in the battery ECU. That is why your car can through codes. Hobbit has a good right up of this circuit here. Prius battery exploration The ground fault loop is connected to the battery through the most negative voltage sensing wire. I found it helpful for testing to disconnect the orange plug from the ECU to break this connection.
    The safe thing to do is first remove all the buss bars. Like Tampaprius I have used a regular voltmeter to find the leaks. You can measure volts or ohms. My meter has a 200M ohm scale. Readings in the 100M ohm range were tripping the leak code. A meger meter will make it easier to find the leaks. Be sure to check both terminals on every module. My solution for the Gen I leaks was to wash each module separately. I used dish soap and water and dried the modules in the sun. Just a little dried up electrolyte with some dust and dirt is conductive enough.

    Brad
     
  14. flyboy09

    flyboy09 Junior Member

    Joined:
    May 11, 2005
    56
    4
    0
    Location:
    Seymour Tennessee
    Vehicle:
    2005 Prius
    Model:
    N/A
    POAA6: code1=0, code2=526, code3=612, code4=0, code5=0
    other dtc: C1259 no snow flake
    dtc C1300 yes snow flake
    dtc C1310 yes snow flake
    dtc C1532 yes snow flake
    dtc B1421 no snow flake
    dtc B1271 no snow flake

    have no idea what to look for on any of these reports, thanks
     
  15. flyboy09

    flyboy09 Junior Member

    Joined:
    May 11, 2005
    56
    4
    0
    Location:
    Seymour Tennessee
    Vehicle:
    2005 Prius
    Model:
    N/A
    when i had the battery apart, i cleaned all corrosion with vinegar and used dielectric grease to help prevent future corrosion. two of the screws that secure the battery cells from the bottom broke off on me, during reassembly... i just left it as was, as everything becomes secure when clamped together...just not sure it that might have something to do with my POAA6?
     
  16. nh7o

    nh7o Off grid since 1980

    Joined:
    Dec 10, 2011
    1,686
    332
    0
    Location:
    Hawaii
    Vehicle:
    2009 Prius
    Model:
    II
    INF code 526 = "Insulation resistance of (or between) high voltage circuit and body is low"
    INF code 612 = "Insulation resistance of HV battery, battery ECU, system main relay, or system main resistor is low".

    These indicate that there is a high resistance leakage from the battery terminals to the chassis ground. It could be through the battery control ECU, through the inverter, through the A/C compressor, through the transaxle, or anything that connects to the battery DC lines. It will require separating the various branches and checking for leakage in each one. There have been reports of this situation being caused by the A/C compressor, which can be easily checked by removing it's power leads.

    A missing screw in the battery box won't affect this error condition. Any left over vinegar that was not washed off could provide a leakage path.

    The middle of this page shows the basic idea behind the leakage detection circuitry:
    Prius battery exploration
    The C1259 "Regen Malfunction" is related to the above isolation fault.
    C1300 Skid control is probably also a result of above.
    Not to worry about the others for now, and they could possibly be low 12V related. Find the HV isolation fault first and go from there. Reset the HV system by removing the 12V for a couple of minutes and reconnect.
     
    #16 nh7o, Mar 27, 2015
    Last edited: Mar 27, 2015
  17. TampaPrius.com

    TampaPrius.com Active Member

    Joined:
    Feb 20, 2013
    457
    289
    0
    Location:
    Tampa, Florida
    Vehicle:
    2008 Prius
    Model:
    N/A
    You don't need one. You can detect a voltage leak with a regular harbor freight made in China digital volt meter. Just put one lead on the side terminal of a module and the other lead on the chasis (battery bottom case) If you get any steady voltage you have a leak.

    FWIW- If you find a leak, it's best to scrap the pack and get a rebuilt, used or new.
     
  18. John Gjata

    John Gjata Junior Member

    Joined:
    Jan 10, 2018
    27
    7
    0
    Location:
    San Diego
    Vehicle:
    2007 Prius
    Model:
    N/A
    How difficult to get to hv batt and test. Dealer wants $900’+
     
  19. hchu1

    hchu1 Active Member

    Joined:
    Sep 28, 2006
    315
    126
    0
    Location:
    Houston, Tx.
    Vehicle:
    2014 Prius v wagon
    Model:
    Two
    Here is a video,



    While you're at it, check and clean out your hv battery fan near the 12v battery side.
     
    John Gjata and bisco like this.
  20. bisco

    bisco cookie crumbler

    Joined:
    May 11, 2005
    95,319
    43,208
    0
    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    testing is fairly complicated. you'll need to read up in the rebuilding threads.

    i don't know what the dealer is trying to pull, but they can get it through the obd in no time.
     
    jerrymildred and John Gjata like this.
Loading...