Hiding a spare electronic key in the Prius Prime...

Discussion in 'Prime Technical Discussion' started by Insighter, Feb 4, 2018.

  1. Insighter

    Insighter Active Member

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    Hello. I was wondering if there is a way to get an additional reasonably-priced mechanical key (the one you can remove from the key fob). Here is why I'd like to have an extra one:

    On my previous cars that had the security chips inside the head of the key, I would always go to a Home Depot and have an extra key made using a blank that didn't have the chip (so it was cheap). I would then hide this chipless key under the car in one of those magnetic key stash boxes. I would then hide my valet key really well in the trunk. If I locked myself out of my car, I could retrieve the chipless key, which would open the doors and trunk. I could then get the valet key and be on my way with only a minor hassle and delay.

    I want to do something similar with an extra mechanical key for my Prius. Of course, to be able to drive off, I'd have to hide a spare electronic key in the car, and I'd have to disable it by removing the battery or placing it in some sort of bag or container that would keep it from communicating with the car.

    I could just use the mechanical key from the spare electronic key, but I'd rather not risk having it in the magnetic box in case it falls off. I'd really like to buy an additional electronic key with the included mechanical key, but I believe they are quite expensive.

    I just don't want to be locked out of my car in the middle of nowhere with no ability to get in it. Can a mechanical key be purchased separately? Or is there a cheaper electronic key (perhaps with fewer features from one of the other Prius models) that I could buy to use as the hidden spare key?

    Or does anyone have any better ideas (and please don't suggest not losing my keys as that is obviously Plan A)? Thanks!
     
  2. dalcon95

    dalcon95 Senior Member

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    The car won't lock the doors if the FOB is in the car. The machanical key is only needed if the battery in the FOB is dead and you need to get into the car. So in other words, you can't lock yourself out of the car.
     
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  3. dalcon95

    dalcon95 Senior Member

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    That is if the car is off.
     
  4. Insighter

    Insighter Active Member

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    Yes, I read that in another post (that you can't lock your keys in the car). However, that doesn't cover another situation in which you might lose your key and thus not be able to get back in your own car. So, if I'm traveling and in some motel in some small town, and I lose my key, it could take hours or even a day or more to get back in my car (if I have to have a key shipped). That is the scenario I'm trying to address.
     
  5. dalcon95

    dalcon95 Senior Member

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    I might be wrong, but from what I understand on how programming FOB's work, you can only have 2 FOB's programmed to one car at a time. You should have 2 FOB's with the purchase of your car. You can do as you suggested with the second FOB hidden on the car.
    I know if I lost my FOB outside of the car, I would have more problems on my hands as my other keys and FOB's for other vehicles are together. It would be like me loosing my wallet. Just an idea on using your second FOB though.
     
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  6. Insighter

    Insighter Active Member

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    Thanks for these answers. You can really only have two electronic keys programmed to a car at once? That seems like a useless restriction. I don't have anything else attached to my electronic key. My home has a garage door opener and an electronic front door lock that I can unlock via a code or my phone or watch, and I have hidden an actual key to it buried in my yard. I really don't ever want to be locked out of anything, especially while I'm on the road. Even if you have the other concerns you mentioned, the first order of business (potentially urgent business) would be to get back in your Prius and be able to drive somewhere.

    I've never lost my keys or my wallet. In the past, the hidden key has only saved me when I locked my keys in my car (which I know would be very hard to do in the Prius Prime). That was easy to do in my previous cars because they had alarms set to auto-lock the car after leaving it (a feature I dearly wish the Prime had).
     
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  7. walterm

    walterm Active Member

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    There was a thread a long time ago about how to leave the electronic key inside the car and just take the mechanical key with you when you went swimming/surfing/etc (so the only thing you'd have with you wouldn't mind getting wet).

    The concensus was any metallitc shielded bag like the ones EZ Pass transponders are shipped in or a metal box like a Mentos box would work to block the RFIS signal so the car wouldn't see the fob inside the car and refuse to lock. I guess removing the battery would work too if that spare fob was always to be left inside for 'just in case'.

    I don't know about having a spare metal key cut, perhaps a quick stop at a locksmith shop would be in order.
     
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  8. bisco

    bisco cookie crumbler

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    a good locksmith can cut you a new key, you might have to get a blank on eBay. just keep the second fob in the car with a battery taped to it.
     
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  9. Elektroingenieur

    Elektroingenieur Senior Member

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    No. In the Repair Manual (available by subscription to techinfo.toyota.com), Toyota writes, “A maximum of 7 electrical key transmitter sub-assemblies can be registered (this includes any electrical key transmitter sub-assemblies registered when the vehicle was purchased)” (emphasis added).
    Just disable the key so it won’t respond. The Owner’s Manual (PDF) explains on page 280:

    ■ Electronic Key Battery-Saving Function
    When battery-saving mode is set, battery depletion is minimized by stopping the electronic key from receiving radio waves. Press [Unlock] twice while pressing and holding [Lock]. Confirm that the electronic key indicator flashes 4 times. While the battery-saving mode is set, the smart key system cannot be used. To cancel the function, press any of the electronic key buttons.​
    See this thread: Need a new spare emergency Key, not a whole fob | PriusChat
     
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  10. Insighter

    Insighter Active Member

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    Wow, those are some seriously informative answers, Elektro! Thanks for those. I didn't find the other post you linked to with someone trying to do the same thing. Do you happen to know if it is possible to program a new electronic key fob into the system? Or would I have to go to the dealer?
     
  11. bisco

    bisco cookie crumbler

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    dealer, or you could buy minivci and a compatible laptop. some good locksmiths can do it as well.
     
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  12. fuzzy1

    fuzzy1 Senior Member

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    ... if it can DETECT the fob in the car. At least in Gen2 and Gen3, interior detection is not perfect, numerous folks here have posted instances in which the car missed a fob, or by searching they found someplace the fob could not be detected. Though repeatability testing hasn't been reported.

    My spouse often doesn't use a pants pocket, but instead leaves her fob in other stuff in the car when we get out at rest stops or other locations. So when she leaves the car before me, I may end up needing to perform a treasure hunt to find it before I can lock and leave. A couple months ago, she left it in the car again but I still was able to lock the car, not learning until a bit later that her fob was still inside.
     
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  13. dalcon95

    dalcon95 Senior Member

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    So this procedure would have to be done everytime someone was to leave the vehicle being if you ever press any of the buttons of the FOB in your possession, the smart key system would be activated again?
     
  14. Insighter

    Insighter Active Member

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    Dalcon - I don't think that is what that passage is saying. It is referring to keepying the key from receiving radio waves, so the actions of starting and stopping the mode refer only to the key fob in question, not the car's system. So the car and the other fob(s) are independent.
     
  15. Insighter

    Insighter Active Member

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    Okay, I just tested it using both of my fobs and the deactivated/dormant fob remains deactivated/dormant until you press a button on the deactivated/dormant fob. Pressing buttons on another other fob does not reactivate the deactivated/dormant fob.
     
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  16. dalcon95

    dalcon95 Senior Member

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    Lol. Ironically, I did the same and got the same experience. Just reading the manual, it said it would disable the smart key system, which could be misunderstood.
     
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  17. Insighter

    Insighter Active Member

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    Yes, I agree. It's great information from Elektro, though. I have done this with my spare electric key fob. I'll only use it if I can't find my other, so why leave it on, I figure.
     
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  18. Insighter

    Insighter Active Member

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    For those who are interested, it appears the metallic bag from the EZ Pass transponders does not work. I have one that came from CalTrans with my transponder, and I just tried it. Before I put it in the bag, I locked my Prius from a distance. I then put it in the bag, folding the bag over itself, walked up to my car and attempted to open the door. It worked like the bag wasn't even there. I tried twice. The bag is a bit older and has some creases in it. I ordered a replacement sent the other day, and I'll try it when it arrives and post the results here. The woman at CalTrans referred to it as a mylar bag.
     
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  19. Ken Schwartz

    Ken Schwartz New Member

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    Don’t need a bag. Just something waterproof. Remove the battery from the fob. Use spare key to get in from the fob and start car with fob.
     
  20. fuzzy1

    fuzzy1 Senior Member

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    And remember (this part is probably often forgotten) that the fob doesn't even need the battery to be reinstalled before starting the car. Just hold it up against the Power button, and very-short-range RFID will pick it up.

    For improved security, consider not even leaving the fob battery in the car at all. So if a car prowler does break in and find an inadequately hidden fob, most won't know how to make it start the car sans battery.
     
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