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HV Water Pump same as inverter pump?

Discussion in 'Gen II Prius Main Forum' started by clearblue, May 6, 2011.

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  1. clearblue

    clearblue Junior Member

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    I am still trying to figure out the noise coming from behind the dash (driver side) robotic pumping noise. It just goes back and forth.

    Is the coolant inverter pump the same as the HV pump that toyota did a recall on?

    Where are these or This pump located?


    Side note: 3/1/10 @90k i had the HV pump replaced- could this have been the faulty hv pump again?
  2. David Beale

    David Beale Senior Member

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    There are four electric pumps that could make that noise.

    There is a coolant transfer pump, which transfers coolant to and from the thermos when you shut the car off and when you start it. It's noisy and most owners report hearing it.

    There is the inverter coolant pump, which runs when the car is in "ready". This one had the recall. I've never heard it run. In fact, to confirm it's running you usually have to look in the fill chamber for running coolant.

    There is a coolant pump which runs when the A/C system is demanding heat and the engine is stopped. I've never heard this one run either.

    There is a hydraulic pump which runs to keep pressure in the braking system. This will sometimes run for a very short time when you first start up, and will run from time to time as you drive, especially if you are in stop and go situations. I often hear this pump just behind the dash on the drivers side. It's actually quite quiet, but you can hear it pulse.

    The coolant transfer pump is located on the drivers side just behind the thermos, close to the front wheel.

    The other two pumps are located on the passenger side, about mid engine compartment.
  3. Politburo

    Politburo Active Member

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    It's either the "thermos" (coolant storage) or the brake accumulator.

    If you just sit in the car and pump the brakes, you'll eventually trigger the brake pump (don't even have to turn it on for this). If that's not the sound, then it's probably the thermos. The thermos sound is most notable after shutting the car off.
  4. mwesigye

    mwesigye New Member

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    Re: HV Water Pump

    Hi,
    I recently bought a second hand prius 2004 from japan 180,000km mileage .After driving it for some distance about 75 km it displayed check engine light and the master light and the a.c went off .After reading some of the posting i thought it was the inverter pump .when i checked the power cable was pluged off from the pump .I put it back and started the car i noticed smoke coming from the pump/fuse compatment i disconnected it and the car started just fine.

    Could this mean i have a faulty inverter pump? I live in uganda East Africa and prius parts are not available does any one know have a new pump for sale?
  5. Patrick Wong

    Patrick Wong DIY Enthusiast

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    1. Yes, it sounds like your car has a failed inverter pump.

    2. I suggest you measure voltage across the wiring harness connector to the pump to make sure that 12VDC is still available. If not, then you probably have a new problem associated with the smoke that you noticed.

    3. It is unfortunate that you bought this car when parts are not locally available. Perhaps you can find a Toyota dealer in South Africa that would be willing to ship parts to your country. Good luck.
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  6. xpcman

    xpcman Active Member

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    Re: HV Water Pump

    Driving without cooling the inverter will burn it out. The inverter will cost $1000 to $2000 to replace.
  7. seilerts

    seilerts Battery Curmudgeon

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  8. Hal W

    Hal W New Member

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    I am sure clearblue is hearing the pump for the thermos bottle. Do a search on how to replace this pump. You can actually see the pump if you know where to look. Hal
  9. seilerts

    seilerts Battery Curmudgeon

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    For a long time, I thought this was noise from the coolant tank pump or switching valve. But the keyword here is "robotic." The headlight leveling motor makes a servo, "robotic" type noise. I have found in my car that the driver's side headlight servo can get stuck in some kind of loop, where every second or so it slightly adjusts the headlight aim. I can change the frequency or stop it outright by bouncing the back bumper. It is something that would only happen with HID headlights.

    I do wonder what happened to clearblue, since the last post was about getting rear ended and having the brake capacitor backup damaged.
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  10. Hal W

    Hal W New Member

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    That is interesting. Did not realize the headlight had self adjusters. Hal
  11. Patrick Wong

    Patrick Wong DIY Enthusiast

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    This is true only for HID headlights.

    Since Canada has mandatory DRL, HID headlights may not be available there. Pls let me know whether HID is available or not there.
  12. BAllanJ

    BAllanJ Active Member

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    I don't think they are... wasn't an option offered to me, anyway.
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