Coolant Storage Tank Pump

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Collie, Dec 25, 2025 at 4:43 AM.

  1. Collie

    Collie Junior Member

    Joined:
    Jul 10, 2022
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    Location:
    USA
    Vehicle:
    2009 Prius
    Model:
    Base
    Issue: Coolant Heat Storage Tank Pump was making terrible noises. Heater worked fine but car was giving OBDII Code: P2601 Coolant Pump "A" Control Circuit Performance/Stuck Off.

    No coolant leaks.

    Attempts: Installed 2 separate heat tank storage pumps, 2 separate times (hoping the first pump was just defective). Previously, I changed both of the other 2 system pumps in the last 2 months as well. This being the last pump left to replace.

    Result: Code has disappeared and does not return but the Prius seems to just cook the coolant and not perform a bleeding cycle in Maitenance mode or otherwise just running it, after installing new heat storage tank pump.

    The hose running to the pump gets very warm but the pump it's self is cool to the touch and makes no audible noises as to demonstrate it's pumping anything

    In attempting to bleed it (both valves open running tubes back into where you feed the coolant, the car doesn't want to take in coolant but a little gulp every 15 minutes after it's so hot it's steaming. No fluid comes out of the tube in the bleeder port being opened (the one closest to the battery that you stick a #6 key down into to turn and open)

    Which fuse would I want to check? Getting conflicting info online, the backside of the box cover is no help and doesn't say which one it is. No, I don't have a repair manual lol
     
    #1 Collie, Dec 25, 2025 at 4:43 AM
    Last edited: Dec 25, 2025 at 5:08 AM
  2. pasadena_commut

    pasadena_commut Senior Member

    Joined:
    May 2, 2019
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    Location:
    Southern California
    Vehicle:
    2007 Prius
    Model:
    N/A
    Look in the stickies in one of these forums, there is a link to a repair manual.

    What is the history of this vehicle? Is there any chance somebody poured stop leak in the ICE circuit?

    Since the pump isn't making any noise when installed I would try unplugging it and applying 12V directly to it (just for a couple of seconds). If it doesn't spin, then it is a bad pump. You aren't installing no name Chinese pumps, right? That stuff is crap. If the pump does spin then hook a voltmeter to those wires and jump the relay socket which would run that pump. And so forth until everything has been verified, including that the tank itself and the hoses to it are not blocked.

    Watch these if you have not already done so:


     
    #2 pasadena_commut, Dec 25, 2025 at 2:14 PM
  3. Collie

    Collie Junior Member

    Joined:
    Jul 10, 2022
    7
    2
    0
    Location:
    USA
    Vehicle:
    2009 Prius
    Model:
    Base
    Thank you! Do you have any info on how to apply the voltage to the pump for testing? Merry Christmas!
     
    #3 Collie, Dec 25, 2025 at 3:17 PM
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