Heating up of Toyota Prius Wagon third generation

Discussion in 'Prius v Care, Maintenance and Troubleshooting' started by Lahmar, May 16, 2025.

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  1. rjparker

    rjparker Tu Humilde Sirviente

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    Brian is correct, in American English "heat pump" means an air conditioning system that can reverse and also pump heat inside. An inverter coolant pump in your Prius moves coolant through the inverter and down to the transaxle. Sometimes people call it an inverter water pump.
     
    #21 rjparker, May 19, 2025 at 7:46 PM
  2. Lahmar

    Lahmar New Member

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    I completely agree with you. However, what’s strange is that when I removed the original Inventer water pump from the car and compared it with the new one, I tested both using a 12-volt battery and they both ran. So, I took out the original and installed the aftermarket one. Before installing it, I tested it and heard it running, so I assume it works.

    By the way, I’m referring to the Inventer water pump from the heat pump system of the hybrid system, not the water pump of the petrol engine.
     
    #22 Lahmar, May 19, 2025 at 7:47 PM
  3. Lahmar

    Lahmar New Member

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    Good evening everyone,

    I would like to provide you with an update regarding the overheating issue of the hybrid system. I have since installed an original water pump. I also had an electrician carry out electrical measurements. The results showed that both the 12-volt power supply and the signal from the ECU are properly reaching the water pump connector.

    It’s important to mention that this vehicle has two ECUs: one for the petrol engine, and the other for the hybrid system, which is integrated into the inverter itself.

    However, I still haven’t been able to verify whether the feedback signal from the pump to the ECU is functioning correctly.

    I’ve added a link to a video in which I clearly explain how the problem occurs. When I drive on the highway at high RPMs, the issue comes back: the dashboard displays an overheating warning. After that, the car loses power and the engine speed drops.
    At that moment, the engine warning light (engine management light) turns on. At the same time, both fans of the main radiator start running at full speed.

    In other words, I haven’t made any progress and I’m still dealing with the same issue.
    I’m now considering replacing the inverter.

     
    #23 Lahmar, May 24, 2025 at 6:23 PM
  4. ChapmanF

    ChapmanF Senior Member

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    I'm not sure where you are getting this information. Your vehicle has around two dozen ECUs, including one for the petrol engine, one inside the inverter (the "MG ECU"), and one (the "power management control ECU") likely located behind the glove box (at least that's where it is in a gen 3 liftback).

    The inverter cooling pump signals are wired to the power management control ECU, unless they radically changed things from the liftback of the same generation.

    You can verify the RPM feedback from the pump to the ECU by watching the RPM displayed on a suitably-capable scan tool.
     
    #24 ChapmanF, May 24, 2025 at 7:46 PM
    Brian1954 likes this.
  5. rjparker

    rjparker Tu Humilde Sirviente

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    While the transaxle uses continuously variable gear ratios and not discrete gears 1 or 2, your video sounds like the engine is rev'ing excessively high just to get to 100 kmh (62 mph).

    Recommend monitoring engine rpm, inverter pump rpm and inverter coolant temps.

    If you have a clogged catalytic converter or a severely dragging brake, the system would "gear down" to reach speed causing high engine rpms.

    Car Scanner App (typical - not showing engine rpm)
    Car scanner six temps and wps.jpeg

    Still no inverter coolant fluid movement? The above makes me think your inverter water pump may not be getting ground as discussed previously. Did your guy check the pump's 12v and ground at the pump's wiring connector?
     
    #25 rjparker, May 24, 2025 at 9:03 PM
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