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Changed 12V battery and SKS Not Working

Discussion in 'Gen 2 Prius Main Forum' started by McShemp, Jan 31, 2011.

  1. McShemp

    McShemp New Member

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    The original 12V battery was weak already but working. The car sat idle for a couple of weeks, and the battery died. SKS fob would not unlock car doors, and we used the mechanical key to get in. Tried to start the car and nothing happened.

    I installed the elearnaid 12V Optima battery. The SKS didn't work, and I put the fob in the dash to get started. There were some weird dash lights on the first startup: triangle of doom and MFD red car with exclamation point. Second startup and those things are gone, but the SKS doesn't work. Neither does the lock/unlock from either key fob. They both worked recently.

    I cycled the SKS button under the steering wheel and went through another startup cycle. Still the lock/unlock on the fob and the SKS don't work. I have a hard time believing that the batteries in both fobs died at the same time. Any other ideas?
     
    #1 McShemp, Jan 31, 2011
  2. koolingit

    koolingit Member

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    If the buttons on the fob don't work to lock and unlock the doors, it has to be the fob batteries.
     
    #2 koolingit, Jan 31, 2011
  3. Patrick Wong

    Patrick Wong DIY Enthusiast

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    It's much easier and cheaper to replace the fob batteries, then to consider the possibility that the door control receiver, Smart ECU, or the body ECU might have failed. Hence I also suggest that you spend $5 on replacing the fob batteries, then if you still have a problem you'll need to visit your local Toyota dealer for help.
     
    #3 Patrick Wong, Jan 31, 2011
  4. McShemp

    McShemp New Member

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    Okay. The fob batteries are the originals too. I'll change them out and report back. Could dead fob batteries effect the SKS as well?

    Losing 12V power can be a weird experience.
     
    #4 McShemp, Jan 31, 2011
  5. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Yes, if the fob battery is dead, then the only function that the fob can perform is to provide passive RFID identification when you insert it into the dashboard slot.

    I am wondering whether both fobs are used regularly. If one is not used regularly, might it be possible that its battery had died some time ago, unnoticed by you?

    If you depress a fob button, you should be able to see a red LED light up. If you don't see the LED, that guarantees the fob battery is dead.

    However, even if you do see the LED, that doesn't guarantee that the fob battery is strong enough to reliably work with the Smart system.
     
    #5 Patrick Wong, Jan 31, 2011
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  6. qbee42

    qbee42 My other car is a boat

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    Is your new 12V battery fully charged? Sometimes people install a new battery expecting it to be charged, only to find out to the contrary.

    Tom
     
    #6 qbee42, Jan 31, 2011
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  7. snead_c

    snead_c Jam Ma's Car

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    You and Patrick are really wonderful resources to us PCers. Thank you for stepping up to help so often... :rockon:
     
    #7 snead_c, Jan 31, 2011
  8. McShemp

    McShemp New Member

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    I did put a slow charge on the battery overnight. Plus, not mixing up terminals, shorting, arcing, etc. ... just in case anyone needed to know.

    I'll check the 12V bus voltage at the fuse box tonight too. It's not unheard of to have a bad, brand new battery, but I hope that's not the case.
     
    #8 McShemp, Jan 31, 2011
  9. JimN

    JimN Let the games begin!

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    My brand new Toyota 12v lasted ~6 weeks so it does happen.
     
    #9 JimN, Jan 31, 2011
  10. McShemp

    McShemp New Member

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    The fob battery change worked, and they both must have been dead. Unfortunately, the 12V battery did hold its charge. I'm gonna see about getting a replacement 12V battery.

    Thanks guys.
     
    #10 McShemp, Jan 31, 2011
  11. Patrick Wong

    Patrick Wong DIY Enthusiast

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    What means did you use to charge the battery, and what was the starting charging current provided by the charger?

    What voltage did you measure?

    I assume you meant to say that the 12V battery did not charge. Glad to hear that the fob battery replacement took care of one problem.
     
    #11 Patrick Wong, Jan 31, 2011
  12. McShemp

    McShemp New Member

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    I have a 12V battery charger that has an auto setting. I believe the auto setting uses a constant current-constant voltage charging scheme. I can also switch it to a manual 2A or 10A charge and those also seem to reduce the current once the target voltage is reached. I measured the 12V bus voltage at 10.6V after just sitting all day.

    You're right. I meant the battery did not hold the charge.
     
    #12 McShemp, Feb 2, 2011
  13. Patrick Wong

    Patrick Wong DIY Enthusiast

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    OK, it sounds like one cell in your new battery is dead since a fully-charged cell should produce ~2.1V and the 12V battery has six cells. Pls let us know what is involved in getting a warranty replacement from elearnaid.
     
    #13 Patrick Wong, Feb 2, 2011
  14. Sue Airabex

    Sue Airabex Junior Member

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    Hi Patrick. I replaced my door control receiver, but I don't know how to program my old keys to work. Do you? Anybody?
     
    #14 Sue Airabex, Jul 27, 2021
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