Gen 2 Prius wont turnover

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by ack714, Aug 23, 2020.

  1. ack714

    ack714 Junior Member

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    Hello all, I have a 2008 Prius. A few months ago the red triangle with ! appeared on my dash. I did drive it with the warning until my mechanic could scan it. I did change the 12v and things seemed to be ok. He scanned with a professional scanner and found no codes. The scan showed no issues.
    When I went to start the car after it sitting a few days it seemed to start but would only go into neutral. I charged the battery to 12.9 and reinstalled. The car turned over and I drove it about a mile. It seemed fine. When I came back home I turned it off then tried to start it again. It would only go into neutral once again. One change is that I didnt buy the Optima yellow battery because of the triangle, not knowing if the car was close to death. I purchased a Diehard S46B24R, 370 CCA which was listed as compatible.
    Any help troubleshooting or recommendations are greatly appreciated. I cant afford a new second car at the moment due to the circumstances we find ourselves in with COVID19
     
  2. dolj

    dolj Senior Member

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    You need to get the car scanned when the master warning light (MWL - Red Triangle) pops up again.

    When you removed the 12 V battery to charge it, you wiped out the codes stored in some of the ECUs.

    One code that behaves in the way you describe is P0AA6. If you get this code, be sure to get the 2 sub-codes from the freeze frame data. If you only get 526, cycle the car off then on one more time then read the codes again. The second should be there.

    When you have the code(s) share them here and we can help further.
     
  3. Aegean

    Aegean Member

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    I suggest to scan again for codes with Toyota Techstream. It might show some codes that the general professional OBD2 readers might not show.
     
  4. sam spade 2

    sam spade 2 Senior Member

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    And I suggest that you make positively sure that the new battery is FULLY charged before you proceed.

    And check the main battery cable connections and test the charging voltage if you can get it into "ready" mode again.

    If that 12.9 was measured while the charger was still connected, then either your charger has failed OR the new battery is bad (potential shorted cell).

    ONLY AFTER you are sure that there are no major faults in the 12 V system should you pursue any trouble codes that you find.
     
  5. ack714

    ack714 Junior Member

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    Hi Sam, I disconnected the battery charger then tested the voltage on the battery and got 12.9. Do you recommend doing it differently? I could run the battery back to Advance and have them check it out.

    I just check it in the vehicle and it read 12.57
     
    #5 ack714, Aug 23, 2020
    Last edited: Aug 23, 2020
  6. bisco

    bisco cookie crumbler

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    turn the headlights on for five minutes and then read the voltage at the front jump point with a meter, or go to advanced and get a load test.
    your mechanic may not have a prius aware scanner, and you want to read the codes when the trouble lights are on, don't disconnect the battery before doing so.
     
  7. JC91006

    JC91006 Senior Member

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    Just read the codes, your 12v battery is fine.
     
  8. sam spade 2

    sam spade 2 Senior Member

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    This is likely true.

    BUT the entire 12 V SYSTEM might not be "fine".
    ALL of the basic elements need to be checked.....connections and charging......before you pronounce it "fine".

    A few quick and simple checks can save you from making a BIG mistake.
     
  9. sam spade 2

    sam spade 2 Senior Member

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    No. No need to go overboard the other way.
    How long after the charging did it sit before you measured 12.57 ?
    It is probably OK.
     
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