Prius 2011 wont start

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by priusowner28270, Sep 14, 2021.

  1. priusowner28270

    priusowner28270 New Member

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    My 2011 Toyota Prius wont start. I am at a loss as to what the cause might be, because this Prius has worked perfectly until now. I just replaced the key fob battery with a brand new one, so that is not the issue. I have also had AAA come out to help. They charged $200 to replace (and subsequently test) the battery that goes in the rear trunk, they confirmed that it has a 99% charge. AAA could not troubleshoot any further (sadly, when they came out, the car started fine - just my bad luck. Now, the issue seems to have gotten worse and the car refuses to start)

    Here are the symptoms:
    1. The car refuses to start. I first pump the brakes (and hear a faint sound when I do, indicating something is "charging"). I then press and hold the on/off button. Normally, the car would start up on doing this - but now, the panel display does not come on.
    2. The headlights are VERY weak
    3. The lock/unlock functionality also sounds "Weak" and only works 10% of the time, whether I try to lock/unlock the car with the key fob, or using the switch inside the car on the driver's side
    4. Panel display, radio etc refuse to come on when I press the "On" button
    5. And of course, the car does not start.

    I tried to search this site and also read through this article: wheelsjoint _D-O-T-C-O-M_ / toyota-prius-wont-start-causes-and-how-to-fix-it

    Is this a battery issue, or some other issue? Does my Prius have one or two batteries? My rear battery has been replaced with a brand new one. Is that the 12v auxiliary battery, or the high-voltage battery (according to the article above, which I am not sure applies to my 201 Prius)

    I can't even take it into a dealership, and I am at a total loss. What could the problem be?
     
  2. tankyuong

    tankyuong Senior Member

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    Dead 12v battery
     
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  3. Mendel Leisk

    Mendel Leisk Sand Pounder

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    Yeah I think AAA let you down, somewhere. My guess would be the battery is good but the connections not. Or it could be a dud battery.

    Dutch Uncle advice: rather than polling the internet, get yourself a half-decent multimeter, check voltage at the battery, and at the under-the-hood jump start point, and post the readings.
     
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  4. ChapmanF

    ChapmanF Senior Member

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    Yes, notwithstanding what anybody said about the 12 volt battery, all these symptoms you're describing show that the volts aren't getting where they're wanted when they're wanted. That could be the battery or something else, but it's real.

    An inexpensive multimeter, as Mendel suggested, between the jump point in the front fuse box and some body ground, is a good start. Then turn those weak headlights on and see how far that reading drops.

    Then you can take the same meter around to the back of the car. Measure directly between the two lead posts of the battery. If that reading drops by a comparable amount when the headlights are turned on, it's the battery.

    If it doesn't, put one meter probe on the battery's − post and the other on some exposed metal body ground. Does that voltage reading rise when the headlights are turned on? If so, investigate the cable that connects the − post to the body. Remove/clean/tighten as needed. (By "rise" here, I mean become further from zero, ignoring the + or − sign, which only depends on which meter probe you happened to put where.)

    If that's not the culprit, repeat the test with one probe on the battery's + post and the other on the metal clamp attached to it. Remove and clean/tighten as needed if that's where the 'rise' is seen.
     
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  5. priusowner28270

    priusowner28270 New Member

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    @tankyuong
    Thank you for the reply, but I am confused. Where does the 12V battery go - is it in the front or rear of the Prius? I thought the 12V battery goes in the rear, like seen below
    This battery was just replaced with a new one by AAA, and subsequently tested - it has a 99% charge.

    Would you mind sharing a picture of where this battery goes? The make and model # of a high-quality battery, ideally with a link to purchase, would also be helpful. Thanks!


     
  6. rjparker

    rjparker Senior Member

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    Most likely something is discharging the battery while the car is off. The sad truth is the same problem that took down your first battery could be discharging the second. Common parasitic loads are the rear hatch light staying on or something aftermarket that is drawing excessive current all the time. Anything plugged into the obd2 is suspect as well.

    Often a battery charge will temporarily solve the issue and sometimes a jump carefully done with a standalone lithium jump box can get you going. If this is the case, have a mechanic run a parasitic load test. It should be less than 30 ma after two minutes.

    See this post for more on parasitic draw testing:
    Recent replaced 12v battery dead again, root cause? | PriusChat
     
    #6 rjparker, Sep 15, 2021
    Last edited: Sep 15, 2021
  7. priusowner28270

    priusowner28270 New Member

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    @Mendel Leisk Thank you for the reply. Did you mean the front hood? I'm a total novice when it comes to cars..
    Btw is it possible to do a built-in battery test, even though my display doesnt turn on? youtube_DOTT_COMM_/watch?v=9aXrofQmqeQ
    If I purchase a multimeter, could you please point me to a youtube video to test the battery?

    Thanks!

    Thank you, that is incredibly helpful. By "- post" did you mean "negative post"? I have to buy a multimeter now, and will report back if I am stuck. I appreciate it!

    Thank you for the detailed response..sounds a bit complicated, but I will read this again! Since the car doesnt start anymore, it will be difficult to take to a mechanic unless I spend. bunch on towing it. I guess I could try AAA again :(
     
    #7 priusowner28270, Sep 15, 2021
    Last edited by a moderator: Sep 16, 2021
  8. tankyuong

    tankyuong Senior Member

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    I would try AAA again, there should be a warranty
     
  9. ChapmanF

    ChapmanF Senior Member

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    Egg-z᠎ackly.
     
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  10. rjparker

    rjparker Senior Member

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    A battery can discharge in a matter of hours, even if it is new. If AAA can jump it again and it runs, the next issue is why did it discharge.
     
  11. Trailrunner5

    Trailrunner5 Junior Member

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    Jumping on this thread, because this just happened to me. When I opened my car door after work, the unlock chime wasn't typical, and the lights were on for a moment then off. The car was also making a groaning sound. The key fob blinked red/battery fine. Long story short, a couple of coworkers helped jump the car, and it started immediately - and showed a full battery. Of note, my car lights were in the OFF position. Had an uneventful 30 minute drive home. When I parked and turned it OFF, I opened the driver's door and the car chimed as if the car was powered ON. The power button was green (then orange/accessory). It started groaning again. I was unable to fully depress the brake pedal or restart the car. Powered OFF (well, I hope it's off), grabbed a snack and jumped on Prius chat.

    This could be completely unrelated, but the driver side headlight burned out yesterday. Or did it burn out...

    Ideas?
     
  12. rjparker

    rjparker Senior Member

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    Most likely your 12v battery is toast. The "full battery" was your high voltage battery, not your 12v. Once running after a jump the car supplies its own 12v power for computers and other 12v loads. Best thing would be to remove the 12v battery and take it to a auto supply for testing. A new one will be about $200.
     
  13. Trailrunner5

    Trailrunner5 Junior Member

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    YES! 12v did the trick. Have a great week, all.
     
  14. priusowner28270

    priusowner28270 New Member

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    I had AAA jump the car, and that seems to have worked (for now). I drove it for 30 mins and it seems to be fully charged now.

    2 questions:
    1. The AAA technician said that I had the Prius in "Eco" mode, and apparently that drains the battery even when the car is powered off. He said I should leave "Eco" mode off when the car is powered off. Is this true, and it could it have been the root cause of the battery getting drained?
    2. Also, do I need to be starting / running the car at least 3 times a week? Being in quarantine, I sometimes don't do that. Anyone know if there is a "recommended minimum amount of usage"?
     
  15. ASRDogman

    ASRDogman Senior Member

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    Consider the source, aaa.... "eco" mode will NOT drain the battery.
    Unless you have a problem, then probably any mode could possibly do that.
    But when the car is OFF, there should only be a slight drain on the 12v battery, this is normal.
    30 minutes is not enough to charge the battery.
    If you park your car outside, you could get a solar charge and keep it hooked up to the battery and
    let the sun charge the battery during the day.
    If it's garage kept, you can get a battery maintainer and keep it hooked up until you drive the car.
    No more than 4.5 amps.

     
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  16. priusowner28270

    priusowner28270 New Member

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    I see, thanks for clarifying. Trying to determine why it happened....is it because I have not been using the car often? Do I need to be starting / running the car at least 3 times a week? Being in quarantine, I sometimes don't do that. Is a "recommended minimum amount of usage"?
     
  17. Mendel Leisk

    Mendel Leisk Sand Pounder

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    Maybe sis, maybe no.

    I would look into compatible smart chargers, and maybe an electronic load tester. Couple of compatible options, respectively: CTEK 4.3 and Solar BA9.
     
  18. ASRDogman

    ASRDogman Senior Member

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    It will discharge eventually, over time. And if you don't drive the car, it will discharge.
    A decent vom (volt/ohm/meter) is good to have, to check the voltage.
    Same with a battery charger, wether it's smart or dumb!


     
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