hybrid battery fan doesn't seem to come on

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Dale I, May 16, 2026.

  1. Dale I

    Dale I Junior Member

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    on my 2004 Prius...I have a clean fan with air filter installed. I've tested relay and made the fan run in both speeds with my Consulit code checker. Yesterday the red triangle came on with P3000 code. Battery was up to 90F after sitting a half an hour. Fan did not run. I had, previously, checked the notorious fan connector for corrosion and renewed that with waterproof connectors. I checked all the battery modules and they were all 16.4 or 16.5V. Resistance was close to the same in all modules. I had the battery out 6 weeks ago and replaced one module pair that was a little weak. What direction to go?
     
    #1 Dale I, May 16, 2026
  2. Tombukt2

    Tombukt2 Senior Member

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    If you can make the fan run with the Toyota software or some software and a scan tool then the fan runs and is capable of turning on so maybe sensor I v that duct work that aluminum thing I that duct work may not be sending the temp if air correctly ?
     
    #2 Tombukt2, May 16, 2026
  3. PriusCamper

    PriusCamper Senior Member

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    My best guess is sometimes a P3000 doesn't shut off the hybrid system and go into full limp mode, which runs the fan at full blast. Maybe use hybrid assistant app to keep the fan running at full speed when you're driving to confirm Consulit code checker...
     
    #3 PriusCamper, May 16, 2026
  4. JC91006

    JC91006 Senior Member

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    I'm not sure the fan suppose to turn on at 90F, that's a really mild temperature reading. You need to find out what subcodes go with P3000. To point you to a better reason of why the triangle is on. I would suspect the pair you put in 6 weeks ago is probably the reason for the triangle. But that's just a guess
     
    #4 JC91006, May 16, 2026
  5. Dale I

    Dale I Junior Member

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    thanks for the quick replies....
    The reason I changed out the module set 6 wks ago was due to a red triangle...
    I've replaced modules before and generally they work if voltages and resistances are correct.
    The car ran for a couple of thousand miles before this latest incident. Since I wasn't driving the car
    when this incident happened (wife), I don't know if the fan had been on. Since my scanner showed the
    battery temps, I assume the sensors are conveying info to the ECU. I tested the relay on my relay tester and
    it passed the test. I live on the coast in a mild climate, so generally I think the battery stays cool. I'll have to drive it
    again and do a freeze frame to see if anything faults show, at the incident time. At what temp should the fans come on?
     
    #5 Dale I, May 16, 2026
  6. JC91006

    JC91006 Senior Member

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    I don't know when the fan is suppose to come on, but I would think it would be higher than 90F. Your problem should not be related to the fan.
     
    #6 JC91006, May 16, 2026
  7. Dale I

    Dale I Junior Member

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    I'm going to put it back together, drive it till it screws up again, freeze frame the data and go from there.
    I'd love a new battery but....
     
    #7 Dale I, May 16, 2026
  8. JC91006

    JC91006 Senior Member

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    There's a lot of value in a newer battery. Think of the safety and time aspects. How much is that worth?

    There are many places that are selling slightly used batteries for about $1000 (possibly from 2023 or newer). You can buy one of those (camry, rav4, sienna, Prius), whichever one is cheapest in your area. Swap all the modules to your car/case. And then you'll have a reliable battery for 10 years
     
    #8 JC91006, May 16, 2026
  9. Dale I

    Dale I Junior Member

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    any rebuilt battery sellers on the U.S.A.West Coast, that can be trusted?
     
    #9 Dale I, May 16, 2026
  10. JC91006

    JC91006 Senior Member

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    not many rebuilt batteries can be trusted, they would be exactly what you have now. What I was referring to was buying a used battery, OEM part that has all the modules that were produced at the same time. Not batteries that were put together from all different batteries
     
    #10 JC91006, May 16, 2026
  11. PriusCamper

    PriusCamper Senior Member

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    This guy sells the best modules for rebuilds. Also sells fully rebuilt packs too... He teaches Hyrbid & EV repair at his local community college and has spent tens of thousands several times on lab-grade battery testing gear over past 20 years: Manage Hybrid Battery Purchases Easily Online
     
    #11 PriusCamper, May 16, 2026
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