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Strange 12V Issue, Inverter or something else?

Discussion in 'Gen 2 Prius Technical Discussion' started by ATVman, Sep 23, 2021.

  1. ATVman

    ATVman New Member

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    Hi All!

    I made an account to ask for some input about my problem because I’ve been searching this forum for a while and can’t quite find posts with a similar issue.

    I bought a 2008 Prius Touring for $1500 a couple months ago as a car to work on and also to get me to and from my first job. It has around 350k miles, looks like it was fairly maintained. Person I bought it from says they replaced the hybrid battery but I don’t know if they did a new replacement or got a refurbished battery

    The Red triangle is on and I checked Dr. Prius, 2 modules on the hybrid battery were failing, and I used a friends techstream and I got:

    PA080, P3000, B1271 (Historic Code), P0A93

    One day after work the lights came on but wouldn’t start the engine and only shifted to Neutral.

    i checked the 12v voltage and it was very low (11v). I got a ride home and the next day I came back and replaced the battery with a Duralast Platinum that I bought and trickle charged overnight, and it started up fine, but then the Ready light turned off and I lost power in the middle of the road, had to get it towed home.

    I checked the voltage and it was around 11.4, so I gave it another charge for a day and it worked fine after that. About a week or 2 later I took it for gas and after I started it back up it shut down as I was exiting the gas station.

    I tried starting it back up and it started up enough to get into a parking spot. I checked the voltage and it said 11.7-11.9 but then the engine shut off and the ready light came off again.

    I restarted it one more time in a last ditch effort and it said 14.2 volts- I was able to get home and I checked the codes again, all the codes were back except the Inverter code (P0A93) I’m not sure why that one hasn’t popped back up.

    So I’m not sure what’s causing this intermittent 12V issue after replacing it. I was thinking it could be the inverter but I don’t see the code anymore, or could it be caused by the failing hybrid battery? I know it needs to be replaced as soon as possible.

    Sorry for the very long post, but its a bit complicated and I don’t really know how to make it shorter :/

    Thank you for any help, it’s greatly appreciated! :)
     
    #1 ATVman, Sep 23, 2021
  2. bisco

    bisco cookie crumbler

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    check the voltage with the car ready to make sure the inverter is working. then check the draw with the car off to make sure it isn't pulling more than spec.

    you might have a wiring/corrosion issue which can be a bugger to find, or you might need the service manual to troubleshoot the codes and chase down the problem
     
    #2 bisco, Sep 24, 2021
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  3. ChapmanF

    ChapmanF Senior Member

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    That voltage is higher than a 12 volt battery, so it confirms that when the car was in READY then, the converter was doing its job, and charging the battery ... at that moment.

    The P0A93 means the inverter and converter are not being cooled effectively. When they overheat, they'll start shutting down for protection. When the converter shuts down, the whole car's 12 volt electrical system is now running off the 12 volt battery with nothing charging it. When the inverter shuts down, you lose power in the middle of the road.

    Then if you measure the 12 volt battery, you find that it has been run down, because for a while it was powering the car's whole 12 volt system with nothing charging it.

    Commonly, the P0A93 cooling problem has to do with a small electric pump that circulates the coolant for the electronics.
     
    #3 ChapmanF, Sep 24, 2021
    strawbrad, ATVman and burrito like this.
  4. mr_guy_mann

    mr_guy_mann Senior Member

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    As mentioned, P0A93 is usually caused by a fault with the inverter cooling pump- it's a common problem. Open the hood and remove the pressure cap on the inverter coolant tank (it's kind of in the middle-left between the engine and the shiny aluminum cover of the inverter). Put the car in "ready" mode then look in the tank. If the pump is working then you should see turbulence as coolant is moved around by the pump. If not the usually the pump is bad. Generally you should replace it with a new one from Toyota.

    Posted via the PriusChat mobile app.
     
    #4 mr_guy_mann, Sep 24, 2021
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