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Master warning, brake (not ABS), VSC warning lights

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by tharding100, Aug 12, 2018.

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  1. tharding100

    tharding100 Junior Member

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    Location:
    Phoenix, AZ
    Vehicle:
    2008 Prius
    Model:
    II
    2008 Prius. Car runs fine for a few miles then I get the master warning light, the brake light (but not the ABS light) and the VSC Light. No check engine. The car with exclamation shows on the monitor.

    Car seems to run fine once the lights come on. Brakes feel and sound good. If I park it with the engine running, I do hear a clicking which I first thought was the inverter cooling pump (I put in a new pump) but actually is coming from the coolant control valve. The check engine light does not come on and my ODB2 with TorquePro shown no codes. I have put in a new 12v battery to try to fix this. My HV battery is showing 16.2v in each block currently.

    If I turn the car off, it will not come back on. If I press brake and start, I get the same lights plus the "swervy car" light, the ABS light, and the check engine light (still no codes). I can go into neutral and back to park but nothing else. To start the car, I have to disconnect the battery which lets me go a few miles before the problem starts up again.
     
    #1 tharding100, Aug 12, 2018
  2. Maflynn

    Maflynn New Member

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    Location:
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    Vehicle:
    2005 Prius
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    ----USA----
    I have a 2005. Recently had oil changed, air filter replaced. Car had been sitting for 2 weeks( mostly in shade). First trip out (ac on )got stuck in traffic for about 5 minuets:master warning light, check engine light, brake light, SRS light, VSC lights came on. Drove back home ( about 2 miles). Shut car off, turned back on after an hour. All warning lights still on( except SRS).Mileage is 122K. Toyota dealership is 40 miles away. Manual recommends taking car to dealership. Is it safe to drive or will I have to have it towed?
     
    #2 Maflynn, Aug 12, 2018
  3. tharding100

    tharding100 Junior Member

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    I sure wouldn't drive it 40 miles without more information. If your check engine light came on, you will have fault codes. Go to a parts place like Autozone and they will read the codes for you. Or get an OBD2 for $30 or so from Amazon and read them yourself. Most likely it is your 12v battery, but it could be brakes or inverter cooler pump and you could have real safety issues or expensive mechanical problems with the drive. The codes and some Google searches should tell you whether it is safe.
     
    #3 tharding100, Aug 12, 2018
  4. bisco

    bisco cookie crumbler

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    o/p, check the 12v health, even new ones are bad sometimes. you may need a better code reader.
     
    #4 bisco, Aug 12, 2018
  5. bisco

    bisco cookie crumbler

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    check your 12v health, sitting for 2 weeks can kill it. if it is okay, check the inverter fluid reservoir for movement to make sure the pump is working.
    take it to the shop that did the oil change, make sure the oil level is okay, and the air filter is installed correctly, and the housing buttoned down properly.
    if none of that helps, you will need to have the codes read.
     
    #5 bisco, Aug 12, 2018
  6. tharding100

    tharding100 Junior Member

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    Techstream found a P0AA6 fault.
     
    #6 tharding100, Aug 15, 2018
  7. dolj

    dolj Senior Member

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    Vehicle:
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    P0AA6 = Hybrid Battery Voltage System Isolation Fault.

    In addition to the general INF code (or sub-code) 526 which is stored simultaneously when DTC P0AA6 is set, there should be one of 4 other INF codes which will narrow down the specific area of the hybrid drive which is possibly affected. The INF codes are 611, 612, 613 and 614. These INF codes are stored when a malfunction has been isolated after INF code 526 was set. INF code 611 to 614 are set next trip.

    To get the INF codes, click on the snowflake (to access the freeze frame data (FFD)) icon next to the DTC P0AA6. Post the INF codes when you have them.
     
    #7 dolj, Aug 20, 2018
    Raytheeagle likes this.
  8. tharding100

    tharding100 Junior Member

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    II
    With the car in not ready and the codes cleared, I got the MWL in about a minute, which indicated the HV battery itself had the problem. I pulled the HV battery and checked each cell for voltage to the frame. Found one and replaced it with one I got on Amazon. As far as I can tell, the problem is fixed.
     
    #8 tharding100, Aug 20, 2018
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