Making a new key fob?

Discussion in 'Gen 4 Prius Technical Discussion' started by Patric88, Aug 9, 2019.

  1. Patric88

    Patric88 Junior Member

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    Hi all, not sure if this is in the correct section.

    I opened up my key fob to replace the battery (2017 Prius 2) and I noticed the actual electrical components is like 1/3 the fob size. I don't use the panic function and I can live without the locking buttons because I have the door handle button. So what I'm thinking, is there a way to shorten the motherboard, remove the buttons and keep the key fob on me ? It should only be the size of 2-3 quarters stacked when done. I'd then keep this inside my wallet, so I'd never carry a key on me(house is wireless)

    Is this a valid idea?
     
    #1 Patric88, Aug 9, 2019
    Last edited: Aug 9, 2019
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  2. sam spade 2

    sam spade 2 Senior Member

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    Maybe. Probably.
    Or some other way to keep only the RFID function without the buttons or batteries.
    A locksmith who REALLY understands how it all works might be able to help.
    Forget talking to a Toyota shop.

    This should make for an interesting discussion here.

    My honest first reactions was:
    Not worth wasting your time and money to find out.
    Both could be much better spent on other really important things.
     
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  3. bisco

    bisco cookie crumbler

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    wow, why did they have to use such large case? more backward engineering from toyota.

    maybe you could slip it into a small vinyl pouch like a credit card holder or something.
     
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  4. t_newt

    t_newt Active Member

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    It should work and I think it is a good idea--the FOB is a pretty bulky thing all the car companies are making us carry around.

    The only problem I see is where to put the emergency mechanical key that is hidden in the FOB. Maybe it can go on your keychain as a separate key.
     
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  5. Patric88

    Patric88 Junior Member

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    The emergency key will be hidden underneath the car via zip ties, or a very slim hide-a-key
     
    #5 Patric88, Aug 9, 2019
    Last edited: Aug 9, 2019
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  6. bisco

    bisco cookie crumbler

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    a few years ago, someone figured out how to make a lexus credit card fob work with prius.
     
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  7. Patric88

    Patric88 Junior Member

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    I'm not against some kind of device that works off nfc to unlock my car when my phone is present. I work in the sales field, my phone is always on me and always charged. So that's not a worry.
    Possible way to splice in a nfc proximity sensor and wire it into the RFID scanner?
     
  8. Patric88

    Patric88 Junior Member

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    Didn't know these existed, I'll order one and a RFID editing machine and I'll get to work on this. When I'm off work, I'll look into the frequencies and such.
     
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  9. Cshigeok

    Cshigeok Junior Member

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    Following =)
     
  10. alanclarkeau

    alanclarkeau Senior Member

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    I think the reality is that they're much the same size as most on the market.

    It's got to be a balance of - big enough to not lose easily, big enough to be robust enough for tradespeople etc, big enough to be able to dismantle easily without a magnifying glass, big enough to hold a reasonable sized battery - and small enough to be reasonably portable. People lose Smart Phones!! A coin sized FOB - the manufacturers would love them because they'd be selling replacements much more often.

    I don't doubt they could be made smaller - but if it's going to have to be mounted on a key-ring, it's small enough.
     
  11. bisco

    bisco cookie crumbler

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    actually, it's much bigger than the past two generations, which seems odd, and less comfortable in the pocket. whereas lexus has a credit card type.
     
  12. alanclarkeau

    alanclarkeau Senior Member

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    Oh - mine is about the same as the FORD I had last. Better than a fixed key with a FOB built in like in the olden days - remember them :rolleyes:?

    The PRIUS has got 3 buttons as well as a built-in key, more than some, though now I think about it, the FORD had 3 buttons - one for the boot, but no emergency button.
     
  13. Elektroingenieur

    Elektroingenieur Senior Member

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    Toyota’s answer is the Smart Key Box, but I have no idea how you’d get one without being a large fleet customer.
    I don’t think so. The RFID reader is in the power switch, but the allow/deny decision isn’t made there; the keys don’t have to be registered again if the switch is replaced. Instead, as Toyota explains in New Car Features (more info), the switch “Receives the ID code and transmits it to the certification ECU (smart key ECU assembly) when the key battery is too weak to respond to the tuner based on the signals from the room antennas.”
     
  14. bisco

    bisco cookie crumbler

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    mine has 4 buttons with the remote a/c
     
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  15. kithmo

    kithmo Couch Potato

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    Another solution would be to hang the key around your neck on a lanyard.
     
  16. alanclarkeau

    alanclarkeau Senior Member

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    I'm looking - but can only see 3 - but it's 1) early morning; and 2) a Public Holiday:
    upload_2019-10-7_10-0-0.png

    Oh - wait, there's more. There's a button to remove the REAL Key underneath.
     
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  17. bisco

    bisco cookie crumbler

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    i have a 2012 plug in prius :p
     
  18. alanclarkeau

    alanclarkeau Senior Member

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    Ahh - so they've downsized for Gen 4 - maybe weight reduction? Mine is 37 grams.
     
  19. bisco

    bisco cookie crumbler

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    upsized. mine is about 2/3 the size of yours. that's why i made the original comment
     
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  20. kithmo

    kithmo Couch Potato

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