04 Prius: Battery Cooling P3000, 123 and 603 solved

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by cbeck, Jul 22, 2024.

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  1. cbeck

    cbeck New Member

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    May 9, 2024
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    Location:
    Ottawa
    Vehicle:
    2004 Prius
    Model:
    N/A
    2004 Prius: I had the P3000 123 codes plus 603 on a vacation, the dealer wanted to change the Hybrid Battery ECU for a used ($750 US) but could not get one in on time. I drove home (10 hrs) and ordered a ECU and changed it myself, ($140) but it was not fixed.
    I changed the fan relay, confirmed the fan worked, and then then followed the troubleshooting for continuity of the wiring. I found it: the brown wire from the ecu to the fan relay was bad. I spliced in a new wire and it was fixed! For battery cooling codes such as these, I recommend that you start with the wiring troubleshooting (in the shop manual) and confirm all are good first, It takes about 1 hour to do.
     
    #1 cbeck, Jul 22, 2024
  2. Tombukt2

    Tombukt2 Senior Member

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    Durham NC
    Vehicle:
    2009 Prius
    Model:
    Base
    Yeah that's a good idea to always check your wiring back there at all the things that work the HV system including the HV battery fan and it's wiring I think there's already a known issue with the big white plug I guess that might house this brown wire that's suspect.
     
    #2 Tombukt2, Jul 23, 2024
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