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Smartkey help!

Discussion in 'Gen 3 Prius Technical Discussion' started by viprius, Jul 19, 2009.

  1. kornkob

    kornkob New Member

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    Yes. that's a real concern. I have a friend who drove to work with his wife, got out, kissed her goodbye, went inside and she drove the car to run an errand.

    Then he had to call my wife to come get him to drive him to his wife so she could have the key.

    (it was a Camry Hybrid, but same type of SKS system so.....)

    If this is a real concern, or you want to lock a fob in the car, a non-SKS fob (black logo) solves the problem.

    BTW-- if you leave a fob in the car, put it somewhere inconvenient. If someone breaks into your car and it is under the mat or behind the sunshade or in one of the may storage areas..... that's where they'll find it. And counting on 'security through obscurity' is foolish. There's a good chance that the person who breaks into your car knows how to use the fob.

    Under the floor mat in the backseat is a good place. Or just inside the door next to the back seat on the drivers side. Or in the 'crack' of the seat where the back meets the bottom.
     
  2. RobH

    RobH Senior Member

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    Not going to happen. The car knows where the smartkey is, and outside isn't going to allow use of the power button. The smartkey has to be inside the car for the power button to work.

    Once the car is started, the key is no longer required. The car will run until it is turned off.
     
  3. rsg

    rsg Member

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    Interesting -- so, even though the doors could be unlocked from 20 feet away, it won't be close enough to allow the car to start -- cool.

    Shawn
     
  4. mrcuiser

    mrcuiser Junior Member

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    If I have it right, once the power button is turned on, you can run the vehicle forever with all the functionality like you have the fob with you, just don't turn off the power button.
     
  5. kornkob

    kornkob New Member

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  6. qbee42

    qbee42 My other car is a boat

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    There are multiple sensors: driver's door, passenger door, hatch, and inside front. It's not just a matter of how close the fob is, it's the actual location of the fob.

    Tom
     
  7. pjksr02

    pjksr02 Active Member

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    I've found that my smart key has to be inside the vehicle for it to start. There are separate sensors to detect the key for the starting function and keyless entry function. Of course, perhaps if she tries to start the car while you're kissing her, with the key is in your shirt pocket, it may start. [...sorry, redundant-the previous posts didn't show when I viewed this thread]
     
  8. RobH

    RobH Senior Member

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    The term "sensors" isn't quite correct. The car transmits signals at 134.5 KHz from a variety of locations on the car. The range of the 134.5 Khz signal to the keyfob is only about 3-4 feet. When a smart keyfob detects the 134.5 Khz signal, it replys with its 315 MHz signal (with a range of about 20 feet). It's rather like the 134.5 KHz signal presses an invisible button on the keyfob. There is only one 315 MHz receiver on the car.

    It's not clear how the car knows which transmitter triggers the keyfob reply. One possibility is that the transmitters rotate, and the detected location is whichever transmitter broadcast last. Another possibility is that each transmitter sends a unique location ID, and the keyfob replys with that ID as part of its message. In any case, the location of the keyfob can be triangulated by which transmitter(s) caused the reply.
     
  9. h00ktern

    h00ktern Member

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    This seems correct since there is an option (using Techstream) to set the proximity "awareness" (my term) to front seat or rear seat [entire passenger compartment].

    I'll verify the operation later and report back.

    Edit: Update, "All" permits "Ready" mode from anywhere within the vehicle.
    "Front" excludes only the extreme rear portion of the cargo area
    - as within a few inches of the hatch lip. If the fob is in the 'exclusion zone'
    an error warning comes up, complaining the fob is not found, and the car won't
    start. I'm not sure of the practical difference this would make, but it is there.
     
  10. qbee42

    qbee42 My other car is a boat

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    True. The "sensors" are actually antennas, and the fobs are active transponders. Sometimes it's best to not overwhelm people with details, unless the details are important.

    Tom
     
  11. RobH

    RobH Senior Member

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    Since you have Techstream, you might want to check out the Smart Access Communications Check function. It's one of the options listed along with key registration.

    The 1-door and 3-door SKS systems behave differently. The 3-door system seems to have 5 transmitters, while the 1-door has 2. Some Lexus have 5-door systems (rear doors have the SKS system).

    Another observation method is to use a portable radio that can receive the 134.5 KHz signal. I have one that can receive the Long Wave AM band, although it only goes down to 150 KHz. Tuning to 269 KHz (double the 134.5) works well enough.

    With a Long Wave receiver, I've noticed that the 134.5 KHz signal is only present while the car is turned OFF. The signal changes when a keyfob is near enough to the car to be detected. The signal changes differently for the correct key versus one for another car.
     
  12. h00ktern

    h00ktern Member

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    I saw that when I was checking earlier, however, being chicken, I backed out :D I figured I'd wait until my new OEM fob comes in, and then investigate some of those options - I think I can fix whatever I might 'break' using the OEM fobs, and add the 3rd while I'm at it.

    I did notice there is a differentiation between clearing the SKS and resetting it. If I get time, maybe I'll put together some screen shots showing the SKS screens & programming options. The little Remarks box is not what I'd call very detailed or well written :rolleyes: It seems you just have to have a sense of adventure, lol