Coolant pump stopped working in car, but worked when tested w/ 12v

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Tetra, Dec 29, 2021.

  1. Tetra

    Tetra Junior Member

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    I have a 2004 Prius and got the red triangle of death while driving. Let the car sit for a day, and started ig-on mode looked at the coolant and saw no turbulence.

    Ordered an inverter coolant pump to install (as I've done twice before), installed it, and still no turbulence in the coolant, or sound.

    Then I hooked up the old pump to a 12v battery and the motor whirs and seems to work fine. I checked the AM2 fuse and it's not blown. Could this be a short somewhere?

    Thanks for any advice.
     
    #1 Tetra, Dec 29, 2021
  2. dolj

    dolj Senior Member

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    Not likely, but I suspect it could be a break in a wire or contact, loose plug, that sort of thing.

    Trace the 12 V + wire back towards the battery until you find 12 V again.
     
    #2 dolj, Dec 29, 2021
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  3. Tombukt2

    Tombukt2 Senior Member

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    I'd go for the loose plugs bent pins could have been damaged by water the pins in the plug that is I have taken one out before and had it run for a minute on the bench once it gets heated up it starts to fail and run intermittently I just had a cheap one fail I don't know 8 months after putting it on I think but breaking them apart I can't tell the cheap ones from the good ones on the inside they look very similar
     
    #3 Tombukt2, Dec 29, 2021
  4. Georgina Rudkus

    Georgina Rudkus Senior Member

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    The impeller is is not mechanically connected to the drive motor. It is a magnetic connection. The motor might test good and run, but the impeller might be jammed.
     
    #4 Georgina Rudkus, Dec 29, 2021
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  5. Tetra

    Tetra Junior Member

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    This reminds me that about 8 or 9 days ago it was raining and I hit a puddle on the driver front side of the car, and I could hear a lot of water shoot up under the car. But does seem like a long time to go without the pump working.

    And you mean the plug that connects from the car to the coolant pump?
     
    #5 Tetra, Dec 29, 2021
  6. pasadena_commut

    pasadena_commut Senior Member

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    A prius can run for a surprisingly long time without throwing a code with a busted inverter pump as long as the weather is not too hot and the car is not pushed too hard, as in driven locally, not on the highway.
     
    #6 pasadena_commut, Dec 29, 2021
  7. mr_guy_mann

    mr_guy_mann Senior Member

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    You should get a copy of the service manual for your car and start looking at the wiring diagrams. In order for that pump to function it needs power and ground at the correct pins.

    You have to test both terminals of the connector with the car in ready to figure what's missing. "12V" comes from a relay while ground goes through a single wire connector( taped to the main harness just above and rearward of the underhood fuseblock).

    Posted via the PriusChat mobile app.
     
    #7 mr_guy_mann, Dec 30, 2021
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