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Motor runs but does not show up on MFD?

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by pasadena_commut, Jan 23, 2023.

  1. pasadena_commut

    pasadena_commut Senior Member

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    Every so often when our 2007 is stopped the motor will start up, but there is no evidence of it on the MFD (no arrows). Typically that happens when we sit at a light for a long time. The battery charge in these situations is not low, that is, it isn't (according to the display) trying to charge up the pack. Other than that, the car seems to be running as it always did.

    Well, the pack isn't what it was two years ago, but it is fine in normal driving. Just not so much sitting with the A/C in park. But when the A/C depletes the pack while parked, and the motor starts, that shows up in the MFD.

    Very rarely I have also seen the MFD show the wheels turning when the car is not moving. It does that only after a stop. I don't recall if the motor was running then or not.

    What would cause those sorts of glitches (motor running with no arrows, wheels turning with zero speed)?
     
    #1 pasadena_commut, Jan 23, 2023
  2. JC91006

    JC91006 Senior Member

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    Many of the issues you are describing has to do with a bad HV battery. The readings are incorrect so it confuses the car on how to behave. How old is your battery?
     
    #2 JC91006, Jan 23, 2023
  3. Tombukt2

    Tombukt2 Senior Member

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    If you see your battery meter the thing that turns green blue and magenta bouncing around from blue to magenta and back to green and then the blue and then the magenta again very rapidly like in 20 minutes 8 minutes 12 minutes that type of thing your battery is starting to fail The HV battery
     
    #3 Tombukt2, Jan 23, 2023
  4. BiomedO1

    BiomedO1 Senior Member

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    Those are software glitches, when one of the CPUs misses a hand-off to another. MFD has a low data priority on the CAN bus, so while the car may be behaving properly; the data your seeing isn't probably up to date. The only thing you can do it make sure all your CPU software is up to date and you've got the latest revisions.

    Even my 2021 does this sometimes; the engine is running but not displayed on the MFD. It's rare, but I have noticed this several times. Usually in the warm-up phase, at a stop light, and right after a switch-over from EV to HV mode.

    Hope this helps..
     
    #4 BiomedO1, Jan 24, 2023
  5. fotomoto

    fotomoto Senior Member

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    Running for heat? Next time it does this, check the HVAC settings. If on, turn off and see if ICE stops running.
     
    #5 fotomoto, Jan 24, 2023
  6. pasadena_commut

    pasadena_commut Senior Member

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    That is a real possibility. The temperature is usually set at 68 or 70, and the fan is always on, so if it is reasonably cold outside the car may turn on the motor. But doesn't a generator run whenever the motor is turning? I would have thought that even if it was just idling (and that seems to be the case) it would be making some electricity and that would go to the pack. Or maybe not. Maybe if it is at a sufficiently low idle the car just takes out the same amount of power to keep the car operating, so no arrow to the pack. No arrow from the battery because then it would look even stranger - motor generating power and it is going nowhere.

    I can also believe the communication glitch theory from a post above. It sure feels like a display glitch.
     
    #6 pasadena_commut, Jan 24, 2023
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