Newbie Prius Crisis: Inverter pump

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by BruceMcyam, Sep 1, 2025 at 10:13 PM.

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  1. BruceMcyam

    BruceMcyam New Member

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    Hey all, new to the prius world here. I picked up a super low mileage 2008 prius touring (85,000 miles) clean carfax with 30 service records.

    I got it for super cheap ($3,000) because it had a bad hybrid, and inverter pump. I replaced the hybrid battery with a remanfactured battery, and replaced the inverter pump. The 12v battery is 3 years old with a bit of corrosion but it still is getting 12v according to my meter. It drives good for about 15-20 minutes and then I get the red triangle and all the dash lights. The ac remains cold and it doesn’t limp. I pull the codes and it shows p0a93 for inverter coolant pump performance. This was worrisome because I just replaced it. I check the coolant tank and there is no turbulence. I attempted to bleed the system by connecting a tube to the bleedant valve, but no coolant will pump into the tube.

    I ordered and received a new inverter pump and replaced it. I again tried to bleed the system, but coolant still is not flowing and wont let me bleed the system. I felt the pump and it is not vibrating. If I just unscrew the bleeder hose, coolant leaks out but even after letting it run for 20-30 minutes, theres no turbulence. I test drove it and after 15 minutes, I got all the dashboard lights again.

    I then checked the AM2 fuse by testing its voltage, got 12.1v - I tested the plugin to the inverter pump and at first it received no power, but then it read 12v.

    There is no turbulence, the am2 fuse is fine. I’m not sure why the coolant pump is not working. I’m out of ideas, could it be the 12v battery? Need help!!
     
    #1 BruceMcyam, Sep 1, 2025 at 10:13 PM
  2. Brian1954

    Brian1954 Senior Member

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    The two inverter cooling pumps that you bought, are they Toyota OEM or an aftermarket pump.
     
    #2 Brian1954, Sep 2, 2025 at 1:41 PM
  3. Tombukt2

    Tombukt2 Senior Member

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    Put hand on them in ready mode do they vibrate ? You feel it . Now squeeze the hoses like milking cow you feel the pump? When you change the pump and you dumped cooling in the reservoir for the first few seconds you heard a bunch of sucky noises and then primed and leveled out?
     
    #3 Tombukt2, Sep 2, 2025 at 1:51 PM
  4. rjparker

    rjparker Tu Humilde Sirviente

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    Probably aftermarket pumps. Pretty common when they don't last long.
     
    #4 rjparker, Sep 2, 2025 at 2:06 PM
  5. pasadena_commut

    pasadena_commut Senior Member

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    The OEM pump is reliable, the others, not so much. Some crap out early like the OP experienced. I had a Dorman which would sometimes just decide that this trip it was not going to run, but then would be fine on the next start. The OEM part number is G9020-47031 with a list price of $230.63 but it is around $50 less if ordered online from a dealer. (Check around, dealer prices vary.) The pump is said to be made by Aisin, and they sell a pump directly for $96.79 at RockAuto, AISIN WQT800, which looks just like the OEM one. (Or at least somebody reported that it did somewhere on this forum.) Some members here have used a variety of other pumps, like from scooters with some success. I don't believe that the part numbers have been posted here though. I also have not seen any pictures of how they were mounted, since they are not the same shape as the OEM pump.
     
    #5 pasadena_commut, Sep 2, 2025 at 3:35 PM
  6. Hayslayer

    Hayslayer Member

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    There's a one wire connector just above the under-hood fuse box. That wire will kill power to the pump, so you may want to check that it's fully seated/no wire pulled out, etc. Sometimes when the pump fails, it blows the AM2 fuse. If it does, you'll know because it kills the car. Unplug that plug, it isolates the bad pump and it lets you replace the AM2 and drive away. Sometimes that plug gets forgotten about and doesn't get reconnected.
     
    #6 Hayslayer, Sep 2, 2025 at 5:43 PM
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