Cold start hv fan limp mode high idle help

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Steve 72, Mar 9, 2026 at 6:13 PM.

  1. Steve 72

    Steve 72 Junior Member

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    starting point is when the engine is cold and I haven’t driven it. Symptoms are as follows high idle Battery fan comes on right away limp mode right away. I have a Dr. Prius app state of charge states it’s between 30 and 60% about 220 V and then it will go to negative bolts alternating I took the hybrid battery apart checked all 14 blocks. No cells are bad. I also replaced the hybrid battery wiring harness that goes onto the one side that’s color-coded. The first code that pops up is a P 3000. The battery fan is clean no dust no obstructions in the filter. I’m at my wet sandwich with this Prius. Any possibility it could be the inverter assembly? I also replaced the inverter cooling pump as that seemed to be a popular reason for the symptoms. Please help I appreciate it
     
    #1 Steve 72, Mar 9, 2026 at 6:13 PM
  2. Steve 72

    Steve 72 Junior Member

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    Bus bars and nuts no corrosion whatsoever. I cleaned it as well thanks
     
    #2 Steve 72, Mar 9, 2026 at 6:14 PM
  3. Steve 72

    Steve 72 Junior Member

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    Nobody??
     
    #3 Steve 72, Mar 9, 2026 at 7:33 PM
  4. PriusCamper

    PriusCamper Senior Member

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    Howdy... Did you load test the individual modules when you took the pack apart or just checked the voltages? We can walk you through a load test.

    Also, did you find any corrosion where the pins at the ECU plug into the voltage sensing harness? If so then you'll want to look inside the ECU because there's a pin that connects to the circuit board that can grow corrosion and cause signal noise that leads to a P3000 error code.
     
    #4 PriusCamper, Mar 9, 2026 at 8:17 PM
    Brian1954 likes this.
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