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01 Prius P3125 - 287 HC ECU

Discussion in 'Generation 1 Prius Discussion' started by Jtkay, Dec 1, 2016.

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  1. Jtkay

    Jtkay Junior Member

    Joined:
    Dec 1, 2016
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    Vehicle:
    2001 Prius
    Model:
    I
    About three weeks ago I hit a speed bump with my Prius 01 and a host of warning symbols blasted across my dash. One hour later, the warning lights disappeared, but since I was concerned I brought it into the hybrid specialists to see what was going on. Apparently there is a malfunction in the HV ECU and the ECU must be updated, with a new part to match. My dilemma is this: since my garage visit, the vehicle drives normally and no warning lights have come back on. I am tempted to think that something went awry when I hit the speed bump but now has resolved. Anyone have a similar experience, or thoughts? The cost to replace this (including labor) is about $1,200, so it is not a trivial concern. The car has 42,800 miles. Thanks much.
     
    #1 Jtkay, Dec 1, 2016
    Last edited: Dec 9, 2016
  2. Pri-Eye

    Pri-Eye Junior Member

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    Nov 4, 2015
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    Vehicle:
    2001 Prius
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    N/A
    The Diagnostics Manual (RM771E) on Page DI-234 notes that codes: 3125-284, P3125-286 & P3125-287 indicate an internal short in the Inverter, requiring replacement of it. However, since this failure is intermittant, you should "Check for open, short and +B short in wire harness between HV ECU MFIV and MIVG terminals and converter & inverter assembly M–FINV and M–GINV terminals."

    The manual also notes that you should address all other recorded codes First, before addressing this code.
    The diagnosis of replacing the HV ECU is likely because of other codes... or, they were guessing.

    That being said, replacing the HV ECU is really easy and people on this board will help you through it step-by-step. The part isn't that expensive on eBay, less than $100. It's located under the front passenger footrest and just requires pulling back the carpet and removing a few bolts. It's SO EASY! Then resync the immobilizer, (turn the key to ON and wait 30 minutes).

    All that being said, if you don't have a continuous malfunction, there's no need to do anything about it.
     
    #2 Pri-Eye, Dec 13, 2016
    Memaw likes this.
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