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Electric Motors not running intermittently

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Smythe, Aug 19, 2019.

  1. Smythe

    Smythe Junior Member

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    Hello Everyone,

    2012 Prius V three
    Wondering if anyone here is familiar with the issue here the electric motors is not coming on as expected.

    My wife first noticed on Friday that the car was not operating like normal, she drove it to me and of course, I didn't find anything wrong.
    Saturday night we were coming home and I experienced the same issue.

    - When the car is idle, the gas engine stays on.
    - When starting from a stop, the gas engine labors and its noticeably slower off the line
    - While driving, the car never enters EV mode.
    - The battery indicators seems to not move, up or down.

    It was like this for ~10 minutes or so before the EV mode came back on.
    I pulled codes yesterday and I got nothing, nothing stored, no CEL even while it was happening.

    Upon research, my first move is to clean the HV battery fan/ duct work. I read that over heating the battery could cause the electric motors to not come on, and wouldn't necessarily throw a code unless it was extreme.
    My wife was carting our German Shepard for the last year, I'm sure there is hair in the fan.

    Any other leads for what could cause this???

    Appreciate the help.

    Smythe
     
  2. CR94

    CR94 Senior Member

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    Yes, check battery cooling duct and fan. Can you read battery temperature when this occurs?
     
  3. bisco

    bisco cookie crumbler

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    was it hot out? there's a battery protection mode until the battery comes down to a certain temp.

    how many miles on her? the older and weaker the battery, the earlier and more often it may enter this mode
     
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  4. 2k1Toaster

    2k1Toaster Brand New Prius Batteries

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    The Prius does sometimes randomly do this as it does a cycle on the battery. This happens in Gen-3 and up. As the battery gets weaker and weaker over time, like yours being 8 years old now, it is more and more noticeable.

    Now this can also be a sign of the car protecting itself. This can be because the battery is too hot or inverter is too hot. On a Gen-2 and Gen-3, first thing I'd check is for turbulence in the inverter coolant pump reservoir. It is a pump that can die and it's only function is to run the cooling loop that is just for the inverter. When the pump dies, the car works just fine, but the inverter gets hot. So the longer you drive, the hotter it gets until eventually, it does as you describe. Eventually it will just refuse to move as you encroach temperature error territory from temperature warning territory. On the Gen-2 the pump has been part of a recall. I don't believe so on the Gen-3. But it is still a weak point.

    Also on the Gen-3's the inverter itself is a weak point, whereas it is not on the Gen-2. The Gen-2 is built like a tank. The Gen-3 is built to save money. There is also a recall out for the inverter. A partially failed inverter could cause self heating and then the symptoms you describe.

    If the battery is hot, this is easy to tell. The fan will come on in the back. Turn down the radio and roll up the windows, and listen to the little HV battery fan. If it is loud, your battery is hot.
     
  5. ASRDogman

    ASRDogman Senior Member

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    Since you have a dog, with LONG hair, I suggest the following:
    Hybrid Battery Fan Filter: $12.78
    Part Number: G92DH-47010

    Also install this foam filter with it, you cut it to fit:
    Lowe’s Air Filter
    Frost King (common 15x24) Washable Filter
    Item # 78359 Model # F1524 $2.00

    This attaches to the right rear air inlet, next to the seat back.
    Easy to remove and wash with water.
    I have to dogs, and have other dogs I train and transport, and this catches it all.
     

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    #5 ASRDogman, Aug 19, 2019
    Last edited: Aug 19, 2019
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  6. Grit

    Grit Senior Member

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    It can also be the 12v battery is not able to retain operating voltage charge so ICE is staying on to continuously or longer charge the 12v because it’s deteriorating,
     
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  7. ChapmanF

    ChapmanF Senior Member

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    The engine running isn't directly needed to charge the 12 volt battery though.

    Power to charge the 12 volt battery comes from the DC/DC converter and from the high voltage system in the car (so, from the traction battery, whenever the engine isn't running). The engine will, of course, cycle and run as needed to keep the traction battery charge within limits. The 12 volt battery is getting a constant charge whether the engine is running or not.
     
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  8. Smythe

    Smythe Junior Member

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    I pulled and cleaned the HV battery fan tonight.
    Unfortunately it was not as dirty as I suspected, there was almost no dog hair in/around it. There was a good deal of dust on the fan the I cleaned off, but I doubt enough to make an impact.
    And nothing blocking the intake or exhaust of the fan.

    It’s the Prius V and the dog is in the back hatch area. The inlet is under the passenger rear seat facing forward so not much dog hair made it in there.

    It was hot Friday, but not really Saturday night, I drive it ~15 minutes to my brother in laws and it sat on in the driveway for 10 minutes. Leaving is when I noticed the motors not coming on.

    I will take a look at the inverter pump next.
    How would I know of the pump is working? Can I feel it in a coolant line?
     
  9. Smythe

    Smythe Junior Member

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    Couldn’t help myself and went out to check the inverter pump.

    I can feel it pulsing in the lower coolant tube, so seems to be working, at least when when I was checking it just now.

    I did have another issue.
    - While pulling the HV fan out I took out the HV battery interlock, just because.
    - Checking the inverter pump, I couldn’t get a ready light
    - I pulled the back apart again, checked all connections still not start.
    - Pulled and reinserted the interlock switch again
    - Car started but now with a HV system warning light.
    - Went inside to get my ODB2 BT reader, when I came out, no more light.
    - Checked codes again anyway, got P0A0D. HV interlock switch.

    I don’t think it’s related but...

    Everything seems to be working fine at the moment.
     
  10. Maarten28

    Maarten28 Active Member

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    I would recommend buying a scanguage or an OBDII plug and using an app like hybrid assistant to check the state of the car.
    That, or go to a Toyota workshop and have them diagnose it.
     
  11. Smythe

    Smythe Junior Member

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    Right... I use Carista, which I typically like and has worked well for my other cars including the Prius.
    Again, The only code was P0A0D for the battery interlock, which I was messing with at the time I got the code.
    No other codes active or stored.
     
  12. Aaron Vitolins

    Aaron Vitolins Senior Member

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    If your 12v is more than 4 years old, change it. Also your electric motors always are working if you're moving. Your gas engine is just staying on. A hybrid Toyota can't move without the electric motors
     
  13. jerrymildred

    jerrymildred Senior Member

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    Well, it's been over a week. Everything still OK? The HV interlock error was because you didn't have the interlock properly seated. You insert the interlock, fold down the handle, and then slide the handle toward the pivot hinge. This locks it in place and also closes a pair of contacts that tell the ECU that the interlock is in place.
     
    #13 jerrymildred, Aug 28, 2019
    Last edited: Aug 28, 2019
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  14. Mendel Leisk

    Mendel Leisk Senior Member

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    I've cleaned that fan a couple of times, without pulling out the interlock switch. I'm still standing. :whistle:
     
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  15. jerrymildred

    jerrymildred Senior Member

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    Right. No reason to pull the interlock just to unplug a 12V fan motor. Totally different system.
     
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  16. Mendel Leisk

    Mendel Leisk Senior Member

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    I found too, you can completely clean the fan without removal; just pull off the ducts connecting to it, any covers.
     
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