Multiple power management software updates?

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by pasadena_commut, Jul 30, 2026 at 6:40 PM.

  1. pasadena_commut

    pasadena_commut Senior Member

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    My 94 year old mother has finally agreed to stop driving at the end of this month. Final straw was when her eye doctor told her she wouldn't pass the DMV eye exam. That means her 2012 (thought it was 2010, but no, it's a 2012) needs to find a new home. I'm hoping my son will take it since his FJ Cruiser only gets 10 mpg on short trips, which is about all they do. If one of them ever gets a job again it would make much more sense to drive there in the smaller vehicle.

    Loaded the VIN into my Toyota account to see what has been done. Mostly oil changes and tire rotations but also a side airbag recall. Oddly it also has two power management software updates:

    2/28/19
    RECALL J0V ~|~VERIFY RECALL J0V ~|~ ~|~PERFORM J0V UPDATE TO THE POWER MANAGMENT ECU WITH NEW SOFTWARE

    3/4/14
    SSC EOE ~|~VERIFY SSC EOE ~|~ ~|~PERFORM EOE, SOFTWARE UPDATE FOR MG ECU AND POWER MANAGEMENT ECU

    I think the more recent of these is the change associated with the class action lawsuit over inverters burning out, but what was the earlier one?

    I don't know yet if it has a cat shield. Mine does but the 2012 was garaged its whole life, so maybe not. Hope so. Because having two Prius in the driveway is likely to attract power tool activity.
     
    #1 pasadena_commut, Jul 30, 2026 at 6:40 PM
  2. ChapmanF

    ChapmanF Senior Member

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    E0E was the first one intended to prevent damage to the inverter. It included updates to the firmware in the power management control ECU (under the dash) and in the MG ECU (inside the inverter).

    Not every technician who applied the E0E recall remembered to reflash both ECUs. (There was a mixup in editing the technical instructions, so if you were following one part, you would remember to do both, but if you were following another part that should have matched, you might miss one.)

    J0V was a later recall and was made for two reasons. One was to fix a bug in the power management control ECU firmware, not about preventing inverter damage, but about responding in the right way if it occurs. The car's supposed to respond by going into a "limp mode", but under some conditions before the J0V fix, it would just shut the hybrid system right down, which could be more likely to cause an accident. So J0V fixes that.

    The other reason for J0V was to mop up the mess where the earlier E0E recall didn't get all the cars updated in both ECUs. So part of J0V is to make absolutely sure both of those ECUs have been updated the way E0E was supposed to.

    Toyota developed a whole new software update wizard for their Technical Information System that now automatically verifies the versions loaded on all the ECUs involved, and uploads confirmation to the mothership.

    It's like they really, really didn't want to see any more news about recall firmware updates getting incompletely applied.
     
    #2 ChapmanF, Jul 30, 2026 at 6:53 PM
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