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Gen II Prius Battery Staying in Green Often Now

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by AshleyNK, Sep 5, 2015.

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  1. AshleyNK

    AshleyNK New Member

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    Hi everyone - we have a '04 Prius with 178k miles on it. We drive long (500 mile each way) trips at least 1x a month, so have been keeping our eye on the battery lately hoping to catch an sign of an issue before it happens.

    Lately we've noticed the car tends to stay in green (7 bars) more often then it ever did before. Sometimes it will go down to 6 blue, but pretty quickly it comes back up to 7. We don't live in a particularly hilly area (NYC) but this only happens when driving outside of the city upstate. We are actually getting a little better MPG than we used to (47mpg vs 45-46) according to the dashboard.

    A few weeks ago we also heard the Prius fan come on loudly for about 10 minutes. We'd never heard this before. It happened after starting and stopping the car a lot in 90 degree weather during a move so maybe that's why?

    I have read numerous threads about battery loss, but so far we haven't seen any jumping from 7>2 or anything like that yet. We know the battery will die one day, but if we can prepare before we end up stranded on a road trip, that would be ideal.

    Also, we currently have a check engine code P1121 which we've had for over 2 years. It comes and goes and our mechanic (and I posted here awhile back) told us that this censor was not essential for the car and wouldn't cause any harm. Could this at all be a factor?

    Thank you!
     
    #1 AshleyNK, Sep 5, 2015
  2. Aaron Vitolins

    Aaron Vitolins Senior Member

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    Doesn't sound like a problem to me, although since your car is now over 10 years old the hybrid battery does have less capacity. but thats normal. Have you ever got the hybrid battery fan cleaned? do pets ever travel in the car? if so that can clog the fan and over time reduce battery cooling.

    also, on hot days try to park in the shade, and run the AC to keep you and your hybrid battery cool!
     
    #2 Aaron Vitolins, Sep 5, 2015
  3. strawbrad

    strawbrad http://minnesotahybridbatteries.com

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    The problem with letting codes like this go is that they will hide any new codes that pop up.

    Buy a Mini VCI cable. It will put you in a position of knowledge even if you do not do your own repairs. Your battery is giving you early indications of a problem. Keep driving it anywhere you are comfortable getting stranded. To get a better idea of your battery condition try this charge and discharge test outlined in this short thread. Unable to determine the cause of the triangle warning | PriusChat

    Brad
     
    #3 strawbrad, Sep 5, 2015
  4. wjtracy

    wjtracy Senior Member

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    Ours is strangely "in the green" lately too, and I hope our battery is OK.
    Normally we get green in winter with heat on, and blue in summer with A/C on.
     
    #4 wjtracy, Sep 5, 2015
  5. AshleyNK

    AshleyNK New Member

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    Thanks, I'll look into the VCI. We get the code read very frequently whenever we're near an autozone, but we figured this may be a sign of diminishing battery strength. Does anyone know how long the traction battery can go with depleted power?
     
    #5 AshleyNK, Sep 5, 2015
  6. AshleyNK

    AshleyNK New Member

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    Also -- one more thing to note. We usually park it on 7 bars of green and when we wake up it's on 6 bars of blue.
     
    #6 AshleyNK, Sep 5, 2015
  7. edthefox5

    edthefox5 Senior Member

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    P1121 is coolant control valve. Its a common malady and was covered under warranty for a while. If you haven't take your car to the dealer in a while ask them to scan the vin for any updates that the car has missed. These are free updates.

    I recommend you go to Toyota.com/owners and join. It asks you for your vin and then you'll be able to search the cars service history. Anywhere in its life if its seen an authorized Toyota service center there will be a notation in there. I also use it to log my personal maintenance history too. And it will list any TSB's that have been performed on the car.

    You can also search P1121 by using the search forums button on top of page here on PC.

    And lastly google Luscious Garage. There a Hybrid facility in California and they discuss the P1121. There one of the best Prius servicers and theirs some interesting discussions on there concerning Prius issues.

    Good Luck.
     
    #7 edthefox5, Sep 5, 2015
  8. AshleyNK

    AshleyNK New Member

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    Thanks! I'm not super worried about the P1121, but I'm going to have the codes pulled again today just in case it's something else.
     
    #8 AshleyNK, Sep 5, 2015
  9. strawbrad

    strawbrad http://minnesotahybridbatteries.com

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    The engine fan or the battery fan?

    Brad
     
    #9 strawbrad, Sep 6, 2015
  10. AshleyNK

    AshleyNK New Member

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    The battery fan in the back
     
    #10 AshleyNK, Sep 6, 2015
  11. strawbrad

    strawbrad http://minnesotahybridbatteries.com

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    You now have two early warnings of battery problems.
     
    #11 strawbrad, Sep 6, 2015
  12. AshleyNK

    AshleyNK New Member

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    This is the what I was expecting. Do these things tend to show up right before the battery goes or does it tend to be more gradual?
     
    #12 AshleyNK, Sep 6, 2015
  13. andrewclaus

    andrewclaus Active Member

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    Autozone can only read industry standard codes. That can be very helpful, but the Prius (and most other modern cars) have a lot of car-specific codes not readable by generic scanners. I just ordered a Mini-VCI to take my maintenance efforts on my aging Prius to the next level.

    Several years ago my Prius had 125K miles on it when I noticed the battery acting differently. I lived in desert mountains then and noticed very rapid charge and discharge on the hills, and the battery fan was running more often. I proactively changed out the battery by looking for good salvage deals on Craigslist. After selling my still-working "core" on CL, my net cost was only $500. 40K miles later I'm very happy with the result and was probably a little lucky.
     
    #13 andrewclaus, Sep 6, 2015
  14. AshleyNK

    AshleyNK New Member

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    Very good point. We're going to invest in a VCI for sure. We have an appointment with a "Prius Doctor" for a battery diagnostic for $30 on Tuesday so hopefully we can see what's going on and make a decision from there. We don't want to fix what's not broken, but we also need a reliable car for long distance drives.
     
    #14 AshleyNK, Sep 6, 2015
  15. AshleyNK

    AshleyNK New Member

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    Sigh - we had the codes read again and now we have a ABS code coming up C1256 (brake accumulator). No brake issues at all, but we are definitely getting this thing into the shop Tuesday. It may be time to say goodbye to our beloved Prius, but we'll see what happens this week.
     
    #15 AshleyNK, Sep 6, 2015
  16. Patrick Wong

    Patrick Wong DIY Enthusiast

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    You say there are no brake issues, so does that mean you do not hear the brake warning buzzer?

    Normally C1256 means that the brake actuator needs to be replaced. If you decide to keep the car you may want to have a used brake actuator part installed - because MSRP of a new part is ~$1,700.
    ANTI-LOCK BRAKES for 2004 Toyota Prius

    I suggest you take care of P1121 while you are at it, which requires replacing the engine coolant valve.

    I would not necessarily decide that the traction battery is failing, just because you've noticed the fan turn on from time to time and you see the state of charge fluctuate more than in the past.
     
    #16 Patrick Wong, Sep 6, 2015
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  17. AshleyNK

    AshleyNK New Member

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    Regarding the brakes -- we haven't heard any buzzing noise or felt anything different when braking. Just the check engine light, no brake lights yet either.
     
    #17 AshleyNK, Sep 6, 2015
  18. AshleyNK

    AshleyNK New Member

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    Just an update -- we took the car into PriusKings, a local shop that fixes and diagnosis Prius batteries. They don't believe that the battery's strength is weakening after running a test and driving the car around. We'll keep an eye on it, but fingers crossed we may have overreacted! Our C1256 code disappeared as well, but we'll be checking this vigilantly in case it comes back. Thanks, all!
     
    #18 AshleyNK, Sep 9, 2015
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  19. wjtracy

    wjtracy Senior Member

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    Oh man I do not know the King was up there...could have stopped by we were at Jones Beach last week
     
    #19 wjtracy, Sep 9, 2015
  20. Salvage09

    Salvage09 Junior Member

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    Check your 12V battery. When it starts to go you get all sorts of wacky behavior, and especially unrelated wacky codes.

    12 volt battery:
    Open voltage at 68 °F (20 °C):
    12.6 ⎯ 12.8 V Fully charged
    12.2 ⎯ 12.4 V Half charged
    11.5 ⎯ 11.9 V Discharged

    Check out Toyota Prius: How to Check the 12v Auxiliary Battery Health - PriusDIY.com
     
    #20 Salvage09, Sep 12, 2015
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