Diagnosing Inverter Coolant Pump Issue

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by newpain01, Apr 30, 2025 at 8:57 PM.

  1. newpain01

    newpain01 New Member

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    Hey everyone!

    I have a 2013 Prius getting a code P314A, replaced the Inverter Coolant Pump with a brand new Aisin pump, checked the IGCT fuse which was fine and also replaced the IGCT Relay and I'm still getting "Check Hybrid System" error on the dash, a P314A code and the radiator fans are running at all times. I have tried disconnecting the batteries and charging the 12V battery as well.

    I also unhooked the upper hose going into the inverter radiator and confirmed that no coolant is running, the pump doesn't seem to turn on. I unhooked the connector on the pump and tried measuring voltage on the blue and white wires and was reading 0V, so I am assuming no power is going into the pump.

    Scanned it with Techstream and that's all it shows. When trying to do an Active test on the pump, Techstream throws a fatal error.

    What can I do to test and diagnose this?
     
    #1 newpain01, Apr 30, 2025 at 8:57 PM
  2. PriusCamper

    PriusCamper Senior Member

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    Perhaps @ChapmanF or @SFO or @Mendel Leisk could help yo go further down the Toyota techstream rabbit hole with this? Seems like you've done everything right so far and that getting more options / expertise in Techstream is what's going to help you figure this out. Or at least that's my impression after taking a look at the links:

    upload_2025-5-1_13-10-23.png
     
    #2 PriusCamper, May 1, 2025 at 4:10 PM
  3. Mendel Leisk

    Mendel Leisk Senior Member

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    You had the code prior to pump replacement?
     
    #3 Mendel Leisk, May 2, 2025 at 5:21 AM
  4. ChapmanF

    ChapmanF Senior Member

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    That's the part that interests me even more than any Techstream hocus-pocus. Instead of putting the voltmeter down, I would just keep using it.

    If there's no voltage from the blue wire to ground at the pump (the car is IG-ON for this, right?), then is there any at the downstream blade of the IGCT No. 3 fuse? If not there, is there any at the upstream blade of that fuse?

    If still no, then with the car powered off and the meter set for ohms, is there continuity between the upstream blade of that fuse and those of IGCT No. 2 and of PCU? How about between those and slot 5 of the IGCT Relay socket?
     
    #4 ChapmanF, May 2, 2025 at 2:40 PM
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