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SKS Key Fob: Role of the RFID Chip?

Discussion in 'Gen 2 Prius Technical Discussion' started by jimolson, May 27, 2013.

  1. jimolson

    jimolson Member

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    A married electrical engineer here with two Gen II Prii in his household (2006 and 2009). A recent theft of wife's purse left us with one SKS key fob for each Prius. Despite warnings from this newsgroup that losing your second SKS key is costly, we've been coasting on the remaining keys. Now the rubber webbing on the fronts of these fobs are wearing through. Time to spend the big bucks to purchase new keys and pay the programming charges.

    When I have disassembled Toyota SKS keys in the past I noticed that there is an NXP-branded RFID chip molded into the fob's housing. This chip is entirely separate from the main printed circuit board and is powered from a strong external RF field, whereas the fob's PC board is battery powered.

    Question: Is the functionality of the RFID chip in the vehicle's design entirely separate from the SKS circuit board that unlocks the doors? Specifically, if I demount the vehicle's native RFID chip and install it into an empty EBay fob (or, more simply move the PCB to another empty fob) can I park the RFID chip into the instrument panel's docking slot and rest assured that the vehicle will always start if I can enter the passenger compartment?

    Yes, I know that permanently parking the native RFID chip in the docking slot will make it easier for someone to steal my aging Prius, but that's my insurance company's problem.

    The point of this extended monologue is whether I can avoid a trip to a dealership and re-use EBay second-hand SKS fobs if the vehicle's native RFID chip is always present in the docking slot?
     
    #1 jimolson, May 27, 2013
  2. pjc

    pjc Member

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    I believe you can use the second-hand fobs for keyless entry. It is only for the SKS that you need the brand new fob.

    You do know that you can program the fob (even the SKS) yourself, right? No need to go to the dealership except to pick up the fob (although you can get those online, too, presumably).

    Not sure, but the car might be unhappy about the key being "permanently" in the car. For instance, it may not let you lock it....
     
    #2 pjc, May 27, 2013
  3. jimolson

    jimolson Member

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    Ah, yes, the "won't lock" problem. Know it well. It's the reason the original keys were stolen. She left her purse in the car (containing the now-stolen SKS fobs) and I locked the car from 20 paces using my fob. We didn't hear the computer unlocking the car 3 seconds later but the ***hole in the car next to ours did hear it and claimed her purse.

    So when I read in this forum that losing a Prius' second key fob forces the replacement of a dozen matched electronic modules in the vehicle, this is tied to the RFID chip or the unique ID number stored in the micro on the circuit board?

    Would you know the whereabouts of the keyless entry reprogramming instructions?

    Thanks for your useful post.
     
    #3 jimolson, May 27, 2013
  4. 3prongpaul

    3prongpaul Hybrid Shop Owner, worked on 100's of Prius's

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    The RFID chip is so the car will start when key inserted into dash if the SKS is broken.

    If you lose a fob it is not too hard if you follow the chicken dance instructions to mate a new virgin fob to the car. (assuming you still have one working fob)
    You can do it without Techstream (toyota diagnostic tool). See Finally! How to program a SKS key fob with SKS functionality | PriusChat

    If you have a used fob, it is a little harder to mate to the car, may require Techstream and a seed reset. Cheapest solution is to probably find the lowest price internet seller of new virgin fobs. (unless you're near a shop like ours in Boulder CO - we can reset seeds and use used fobs)
     
    #4 3prongpaul, May 27, 2013
  5. jimolson

    jimolson Member

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    Great news! Is the process for registering a new/virgin SKS fob to the vehicle documented in this forum?

    Thanks for the post, 3ProngPaul. You da grounding conductor...
     
    #5 jimolson, May 27, 2013
  6. garglo

    garglo Member

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    #6 garglo, May 27, 2013
    nh7o likes this.
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