Coolant pump on storage tank operation

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Rick 432, Jan 13, 2026 at 9:02 AM.

  1. Rick 432

    Rick 432 Member

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    Three
    I am hoping someone can help me with this issue. I replaced the coolant pump that is attached to the storage tank (front left) and I know that pump works as I bench tested it. For whatever reason, when I park the car after use that pump is not coming on and moving coolant into the tank. I am hoping someone knows what triggers that pump to turn on. I know the ECU turns it on but there must be a sensor etc. that tells the ECU to send power to that pump. I just want to know the sequence of events that turns that pump on. Thanks to all!
     
    #1 Rick 432, Jan 13, 2026 at 9:02 AM
  2. ChapmanF

    ChapmanF Senior Member

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    #2 ChapmanF, Jan 13, 2026 at 9:54 AM
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  3. pasadena_commut

    pasadena_commut Senior Member

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    Any codes? I'm wondering if the car won't run the CHS pump if it thinks the 3 way valve has failed. It would be pointless to try to move coolant out of the tank if its inlet is blocked.

    Anyway, to verify that at least the wiring is good to the pump, pull the appropriate relay and jump the designated two pins. Same procedure as when bleeding the ICE system. As here, starting at around 13:20

     
    #3 pasadena_commut, Jan 13, 2026 at 1:17 PM
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