HELP! P0A7A HYBRID/BATTERY PROBLEMS. Suggestions?

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Shawn Asal, Oct 30, 2019.

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  1. Inverter generator

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  2. electric water pump

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  3. transaxel assembly failure (MG1 or MG2)

    0 vote(s)
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  1. Shawn Asal

    Shawn Asal New Member

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    2007 Prius
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    I was driving my 2007 2nd gen prius (153k) and like they say the dash just lit up with the hazard light, check engine light, and bring in for maintenance on the hybrid battery screen and my battery percentage was almost depleted and it normally sits at around 80 percent. I got the obd2 and checked in the morning of (was close to home). When I went to check it after the check engine and hazard triangle light was gone. It still did throw the P0A7A (Inverter generator performance) Assumed it's the inverter generator but that's not a common thing to fail so I figured it's the electric water pump but upon further investigation and research I figured that if it was faulty it would throw the specific code for water pump performance. Now I've been told that they can work intermittently work which would potentially cause these problems but I did some research and you can tell if it's working by hearing it when you turn the car on ready and you can also feel it vibrating when you put your hand on it. The coolant is also moving around in the tank. Took it to Toyota for a free diagnostics and they returned with the codes P0A7A, P0A92, and B2799 which is something to do with the ecu. Any suggestions or help guys?! Desperate, broke college student with minimal funds. Any comment or tips on what to do next/check out would be GREATLY appreciated. Thanks
     
  2. Patrick Wong

    Patrick Wong DIY Enthusiast

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    P0A7A and P0A92 might point to a transaxle failure. Both of those diagnostic trouble codes should be accompanied by a three digit subcode which might help to narrow down the issue further.
     
  3. Shawn Asal

    Shawn Asal New Member

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    How do I go about getting the subcodes? So I used a generic obd2 and at first, only pulled the code P0A7A and from the free diagnostics at Toyota they pulled the codes P0A7A, P0A92, and B2799. I pulled the codes again yesterday and only got P0A7A and P0A92 and the same code again P0A92.

    Do you think there is a good chance it good is the inverter generator or more than likely its the transmission?
    I appreciate the advice I have been lurking on here a lot before deciding to post my own and have seen your replies all around! Thank you for the tips and advice Mr. Wong! Hopefully, you can help me solve this as I have barely any money and am struggling with rent let alone paying hundreds of dollars for them just to diagnose my car plus charge me an arm and a leg for labor and parts..
     
  4. Patrick Wong

    Patrick Wong DIY Enthusiast

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    You will need Mini VCI to obtain the three -digit subcodes. If you obtain those then maybe you can get a better idea whether the root cause is the inverter or the transaxle.
     
    Shawn Asal likes this.
  5. Paul OByrne

    Paul OByrne Junior Member

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    I realize this is an old thread, but hopefully you can assist. I have a 2005 Prius with 212 miles which basically was stored in my garage for 2 years with batteries disconnected. Upon my return I reconditioned the HV battery and got it running for about 5 miles and got fresh gas before it went into limp mode right back into my garage. I have added a new 12V battery and I am now down to 3 error codes P0AA1, P0AA4 and P0A7A.
    I have found one suspect corroded connector above the 12V battery but no others yet. With these codes, besides checking relays and connections, should I be checking the HV Control ECU? and if so, how would I do that?
    Also, on one attempt to start I heard a pop sound come from the engine compartment. On my latest attempt, I got the ready light for a moment until the ICE attempted to start and abruptly stopped with a clunk sound and all the warning lights reappeared.
    Any suggestions or wisdom you can share is greatly appreciated.
     
  6. mr_guy_mann

    mr_guy_mann Senior Member

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    In your situation it would be extremely useful to have a scantool (such as a copy of Toyota's Techstream with a mini VCI cable- amazon or ebay- installed on an old windows laptop) that is capable of reading the 3 digit INF or subcode that goes with each of the dtc's you've listed. Then you could look up the specific diagnostic info for that specific fault in your copy of the service manual.

    There are two subcodes for P0AA1 (positive contactor stuck closed), just one for P0AA4 (negative contactor stuck closed), but 14 for P0A7A (inverter generator performance).

    Posted via the PriusChat mobile app.
     
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