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P0A93 Mystery ...

Discussion in 'Gen 2 Prius Main Forum' started by BillMelder, Jul 14, 2022.

  1. BillMelder

    BillMelder Junior Member

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    I have a 2005 Toyota Prius 270k Miles

    This is a used vehicle i bought for a few hundred bucks. I drive it for about a week and the code P0A93 and the VSC light pops up. When i ⁰ the reservoir for turbulence - i saw none whatsoever...

    So out of caution i replaced the iverter water pump and coolant control valve.

    However, i still am not seeing any turbulence in the reservoir... the code and light for the VSC is off now but i dont want to continue to druve it if im missing something.

    Any ideas why there would NOT be turbulence in the reservoir before abd after changing out parts?

    PS - Both parts are new and genuine Toyota parts.
     
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  2. Tombukt2

    Tombukt2 Senior Member

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    What's Justice important when you install the inverter pump and you fill it up with coolant because you should have lost some nobody ever uses 3/4 plugs and blocks the lines as they...anyway you lost some coolant when you replace the coolant if you fill the jug up to almost full to overflow level it takes a long time for it to push the air out of the system and bubble up through the tank and level some people screw the top on so fast they create a big vacuum in the tank and the pump can't move squat. So when you plug up the pump and you turn on the car and you put your hand on the inverter pump I know it's hard to reach down there is the pump in fact humming and running? If no we need to check the a.m. to use under the fuse box and I guess it should have been checked before you started this adventure but here we are do you in fact have 12 volts going to that little plug on the inverter pump when the car is ready if no we need to find out why more than likely the fuse or possibly a bad inverter pump right out of the box generally not with Toyota but everybody else who supplies is part possibly I can't wait to see a Toyota one that's immediately bad out of the box I've replaced five of these as a matter of fact I've stopped using the pump you're installing and it moved to a completely different shaped pump the hose is fit but the pump is completely different shape made for another duty on the same car.
     
  3. mr_guy_mann

    mr_guy_mann Senior Member

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    The coolant control (3-way) is for the heat storage tank for the ICE and had nothing to do with the inverter cooling or P0A93. You can always use a scantool - app that has hybrid control ecu data to see what the inverter temperature sensors are showing.

    Now, with the ignition switched ON (dashboard warning lights on) or in READY, does the pump hum or feel like it's vibrating some?

    If yes, did you bleed the inverter cooling system? There's a bleeder fitting on the front of the inverter. I take off the little rubber cap. Put a length of small tubing (I like transparent hosel from the bleeder and secure it into the inverter coolant tank. Ready up the car then open the bleeder a turn or two. Coolant and any air should flow out- top up coolant level as needed until air bubbles stop coming out (pump should be quieter). Close the bleeder.

    Posted via the PriusChat mobile app.
     
  4. BillMelder

    BillMelder Junior Member

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    i have tried bleeding the system but im not getting any movement whatsoever. ve watcged sevral "how to" videos online and ive tried every which way to make this work. Ive pushed on the hoses and ran may hands down them to make sure there were no kinks.

    i can hear a hum and there is vibration. but im just not seeing the turbulence and its not shooting up hose when i try and bleed.
     
  5. ChapmanF

    ChapmanF Senior Member

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    If that's the case, I'm thinking the system is clogged somewhere. You can unclip the hose from the pump discharge (the tangential nipple, not the central one), or maybe unclip the other end of that hose, where it attaches to the tranny, and pull the end up kind of level with the reservoir. Make sure there's coolant in the reservoir, goose the pump briefly with 12 volts, see if it briskly pumps coolant out that hose. (Try to avoid running the pump without coolant; not good for it.)

    If that confirms the pump itself works, then it's a matter of checking the various ins and outs of that coolant path, looking for somewhere coolant won't flow.
     
  6. BillMelder

    BillMelder Junior Member

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    im outside right now - just did the test... it shoots out water just fine. im just not getting turbulence.

    i drove the car for about 30 minutes today and code came back up as well as the vsc light. thankfully i drove it in circles in front of a empty lot near my house so i was able to pull it into the garage within a minute... like i said i dont want to cause any damage to the system
     
  7. ChapmanF

    ChapmanF Senior Member

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    Welp ... it looks like the pump is fed with coolant from the reservoir (through hose G9226), and pumps it out into hose G9227, over to the MG1 half of the transaxle. And if your test shoots coolant healthily out of hose G9227, then the clog isn't in any of that first part of the path.

    So the coolant then passes through the MG1 heat exchanger and back out through the short little hose G9228 to hop over to the MG2 side of the transaxle. After passing through the MG2 heat exchanger, it's into hose G9229 to the left side of the inverter radiator. From the right side of the radiator, hose G9225 takes the coolant back to the inverter itself (so the electronics get the coolant at its coolest, because it just came from the radiator). After passing through the fins inside the inverter, it returns into the reservoir. (There isn't another hose for that; the reservoir has an opening bolted right up against the outlet from the inverter.)

    Somewhere in that second paragraph, something is clogged. Now just to find it. Kind of a job for a curious plumber.

    [​IMG]
     
  8. BillMelder

    BillMelder Junior Member

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    figured it out!!!

    there was a bolt in hose G9227

    i only found it because i removed each hose and flushed them out individually with the garden hose. i then flushed the entire (both) sytems three times. i drove it for about 5 hours today keeping an eye on the live data and have had no issues.

    i just bought this car from a one time owner who always took the car to toyota for maintenance. he gave me receipts and proof when i bought the car. the pump was replaced about 130k miles ago. but im at a loss at how a bolt got stuck in the hose.

    other than that - im completely happy with my purchase and for the high milage and it being almost 18 years old this little car feels and runs like i drove it off the lot today. i usually donate the priuses i fix up to people who are in need of a vehicle. but i think im going to keep this one. ive grown very fond of it. if that makes sense. :)

    onto my next prius! thanks for all the help!!!
     
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  9. BillMelder

    BillMelder Junior Member

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    sorry hose G9228 was where the bolt was.
     
  10. BillMelder

    BillMelder Junior Member

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    one more thing... while flushing the hoses there was gelatin buildup that came out of some of the hoses. not sure what thats about but i have excellent turbulence and pressure running through the system now
     
  11. ChapmanF

    ChapmanF Senior Member

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    So, the little short one that just hops from one side of the transaxle to the other?

    Funny place to keep a spare bolt.

    Probably the prior owner went some time without changing the coolant. When the corrosion inhibitors are used up in the coolant, the aluminum fins in the inverter and transaxle heat exchangers start to oxidize. Aluminum oxide is this funny jellylike stuff when it's in water. I flushed a bunch out of the bottom of my home water heater when it had an aluminum anode rod.

    Spread out in a pan and allowed to dry, it then looks like some sort of weird breakfast cereal. Maybe you can pulverize it and use it to make sandpaper.
     
  12. mr_guy_mann

    mr_guy_mann Senior Member

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    Congrats on the fix- and the persistent methodical testing that found the problem.

    Posted via the PriusChat mobile app.
     
  13. pasadena_commut

    pasadena_commut Senior Member

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    What size bolt was it?

    My first guess was that somebody stuck a bolt in the end of some hose to keep it from leaking, for instance when changing the inverter pump. But that didn't really make sense, because one couldn't just "forget that it was in there", as the hose could not be reattached.

    That brings up a second scenario - that the bolt came from somewhere inside one of the components which are cooled. So if you can identify the size of the bolt, perhaps somebody here can suggest its original location. You know, in case maybe it should be replaced.

    The third scenario is that some idiot dropped it into a component by accident at a factory, and it has been floating around in your car ever since, only now getting stuck in that particular location.

    Odd things can be sometimes be found in unexpected places. I thoroughly flushed my home water heater recently and an RFID tag came out.
     
  14. ChapmanF

    ChapmanF Senior Member

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    That's just weird.