Inverter pump on Gen 4 status not active

Discussion in 'Gen 4 Prius Technical Discussion' started by Chicagomike, May 8, 2019.

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  1. Chicagomike

    Chicagomike New Member

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    Hi...I'm new to the forum. I recently took my Prius 4 touring in for a recall on wiring harness...they taped it up and sent me on my way. However, my fuel economy started immediately taking a dive. My neighbor--who is a Prius fanatic---put it on IG/Not ready status--and said that he didn't think the inverter pump was working---no sound at all--no turbulence in coolant --hooked up Techstream(?)--and said that the inverter pump status was "off"--he then tried to "active test" the pump---said it wouldn't respond to a manual "on" test. I called dealership--and they said that it could be off--but that if there was a problem it would "throw a lot of codes"--said not to worry...

    But--needless to say--I'm worried. I traveled 3 miles this morning and the display was at 12mpg...!?!

    Any help or advice of any kind would be welcome.
     
    #1 Chicagomike, May 8, 2019
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  2. kithmo

    kithmo Couch Potato

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    I wouldn't worry about the inverter pump, as the dealer said, it would throw up a load of codes and probably go into limp home mode if the inverter pump wasn't working.
    I wouldn't think the pump was designed to be running constantly and may only come on when needed, that is when the coolant reaches a certain temperature.
    But 12 mpg is really low, even for a short 3 mile journey, it does seem like there is something amiss.
    Does it feel normal when driving, no performance drop or rough running when the engine is on etc.
     
    #2 kithmo, May 9, 2019
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  3. alanclarkeau

    alanclarkeau Senior Member

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    It seems it cools MG2 and MG1 as well. All I could find was the following - which doesn't indicate "when":

    upload_2019-5-9_21-35-57.png
    upload_2019-5-9_21-37-3.png

    AND

    upload_2019-5-9_21-38-35.png
    AND

    upload_2019-5-9_21-39-52.png
     
    #3 alanclarkeau, May 9, 2019
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  4. jerrymildred

    jerrymildred Senior Member

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    Welcome.

    If I'm not mistaken, the inverter pump only runs in ready mode and it always runs in ready mode, but @alanclarkeau's information seem to indicate that they have made the pump run on demand in the new generation.

    As for 12 mpg on the display after a 3-mile drive on a cold engine, that sounds pretty plausible to me. Drive it 20 miles and see what you get.
     
    #4 jerrymildred, May 9, 2019
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  5. alanclarkeau

    alanclarkeau Senior Member

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    I think that 12 is a bit low - if I did a 5km drive cold, I'd expect maybe 40mpg (US Galleons), not 12. I've never seen it use that much.

    I'd be going back to the dealer again.
     
    #5 alanclarkeau, May 9, 2019
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  6. Chicagomike

    Chicagomike New Member

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    First--Thanks for taking the time to reply. I'm still having the issue--and tried driving 23 miles out to the burbs this morning. Here's what happened--mpg starts at 8-12, then after about 5 miles rises abruptly to 51mpg...then after another 10 minutes of driving (Chicago traffic) it abruptly drops down to low 20's. I then parked...had a quick meeting and got back in car, restarted, the mpg guage read 199mpg (which it did used to do) then slowly drops down to about 23...then rises abruptly, etc.....

    Thanks! great info--I really appreciate you reaching out. It does appear pump is not like gen 2 and 3--and in fact has a thermostat device--sensor--of some type. I'm now focusing on whether thermostat, etc is sticking. I would note that techstream keeps indicating pump status is "off"..which--along with visual inspection led me to believe the pump itself is faulty.

    thanks--I think that is the case on Gen 4---possible sensor/thermostat sticking--or maybe another error altogether...

    I've had it now for 3 years--and love it---but I typically would get mileage in mid-high 40's even going to gymn...so still trying to figure it out...given the new pump configuration--it may not even be pump--but we'll see...
     
    #6 Chicagomike, May 9, 2019
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  7. kithmo

    kithmo Couch Potato

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    Mid 40s mpg sounds about right for a 3 mile run in cold weather with the heater on, that's what I typically get in Winter with mine.
    Have you changed the trip display at all, your figures jumping up and down like that sounds like you're on some sort of instant mpg reading, rather than a trip reading ?
     
    #7 kithmo, May 9, 2019
  8. kithmo

    kithmo Couch Potato

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    Going back to your initial thoughts on inverter pump, to wrap the said wires on the recall they have to disconnect the wiring plugs from the inverter and I seem to remember reading somewhere that there was a certain procedure to follow before disconnecting so that they didn't damage the inverter, maybe they didn't follow the procedure and damaged it.
    Alternatively could they have not reconnected the plugs right ? it might be worth checking if the plugs are both pressed down tight.
    I think that either of these suggestions should show up fault codes though, these may of course revert back to normal (no codes) after a certain number of starts and your problem may disappear.
    Ask your neighbour if he has a fault code reader and see if there are any codes present.
     
    #8 kithmo, May 9, 2019
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  9. alanclarkeau

    alanclarkeau Senior Member

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    199MPG - that would be that the ICE hasn't run at all. Here, with l/100km, it would be ZERO - and I can get that for up to a km or a bit more.

    A thought - I wonder if they disconnected the 12volt battery and it cleared some history? Maybe - try filling (to the first click) the tank in case it's got a dodgy fill record and isn't sure where it's at - like confused? Reset TRIP A and work from there.

    Actually - what do TRIP A and B read for MPG?
     
    #9 alanclarkeau, May 10, 2019
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