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Fob Light Working but Smart Key Not Functioning

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Ben Rost, Jan 8, 2018.

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  1. Ben Rost

    Ben Rost New Member

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    First post! I just got a 2007 prius (which I love). The fob needed fixing when I got the car; the fob silicone had been pressing down on the unlock button which had drained the battery I'm guessing. I just pried the plastic back a little and replaced the small fob battery, which made all the fob buttons click and smart key functioned great...for a couple of weeks.

    Then it got colder (from 80's down to 40's) and the smart function stopped working after a small roadtrip. I noticed the 'KEY' button under the steering wheel was untoggled so I pushed it back in. That unfortunately didn't do anything.

    The key fob LED lights up when I press the buttons, but the car doesn't unlock remotely or start without the key going into the key slot.

    The battery (12v I believe) was replaced within the last year or two according to the carfax.

    I don't know what the problem is. Maybe the cold affected an electrical connection? Maybe I need to reconnect the 12v terminal (saw that mentioned in a forum)? Any thoughts? Thanks

    Checked the 12 V readout from the MFD.
    • ACC mode (one power button press with no brake): 12.3 V
    • IG-On mode (second power button press with no brake): 11.9-12.0 V
    • Hybrid system start (third power button press with brake): 14.0-14.2 V
     
    #1 Ben Rost, Jan 8, 2018
  2. bisco

    bisco cookie crumbler

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    congrats and welcome!

    the 12v need charging and possibly replacing.
     
    #2 bisco, Jan 8, 2018
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  3. Ben Rost

    Ben Rost New Member

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    What are the safe ranges? Thanks!
     
    #3 Ben Rost, Jan 8, 2018
    Last edited: Jan 8, 2018
  4. TMR-JWAP

    TMR-JWAP Senior Member

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    Maybe I'm remembering this incorrectly, but isn't the SKS deactivated by having the button in the 'pressed in' position?
     
    #4 TMR-JWAP, Jan 8, 2018
  5. TMR-JWAP

    TMR-JWAP Senior Member

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    #5 TMR-JWAP, Jan 8, 2018
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  6. bisco

    bisco cookie crumbler

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    it's not black and white because more than voltage is involved, but 12.4 at a minimum after the car has been off for 5 or 6 hours, with nothing on in the car.
     
    #6 bisco, Jan 8, 2018
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  7. Ben Rost

    Ben Rost New Member

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    Yeah, thought it was the other way around. I don't think it's the problem since it happened when the it was in the 'out' position. Still good to know.

    So >=12.4 V in ACC mode? Could I just charge it with jumper cables? Or would I need something like a trickle charger? Thanks again
     
    #7 Ben Rost, Jan 8, 2018
  8. bisco

    bisco cookie crumbler

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    no, 12.4 with everything off, measured at the battery or jump post. you would need a smart charger from ctek or similar.
    or you can leave the car in ready for 8 hours, somewhere where it won't get stolen.
    then you have to track the voltage over time to see if it is holding.
    and 12.4 would be minimum.
     
    #8 bisco, Jan 8, 2018
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  9. dolj

    dolj Senior Member

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    It may not be the problem, but with the button pressed in (i. e. the deactivate SKS position), the SKS will never work, so you will not know whether what you try fixes the problem.
     
    #9 dolj, Jan 8, 2018
  10. Ben Rost

    Ben Rost New Member

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    Well today the temperature rose to the 70's and I was able to unlock the car remotely again. When I got inside, I pushed the 'KEY' button to the 'out' position and was able to turn on the car with the key in my pocket. Perhaps the battery is on the way out and the temperature sped up the process, but for today, I am happy. Thank you guys for the good resources so I know what I can do in the future!
     
    #10 Ben Rost, Jan 9, 2018
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  11. dolj

    dolj Senior Member

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    I highly doubt it. With readings you gave a few posts back, the battery has plenty of juice to drive remote and SKS lock/unlock.

    There is something else going on. 40ºF (4.5ºC) is not that cold as far as this car goes. The battery works fine at that temp.
     
    #11 dolj, Jan 9, 2018
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