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Aftermarket accessory install: Source of 12v power only when phone w/app / fob is detected in range

Discussion in 'Model 3' started by megabyte, Oct 26, 2019.

  1. megabyte

    megabyte Member

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    I am working on testing a kick sensor for the Model 3 for the frunk and realised the 'trapped person' button inside the frunk is constantly active, meaning tapping this button to pop the trunk with the kick sensor also allows opening the frunk while the car is locked.

    I am aware that there is protections around the use of this button while driving to prevent the hood flying up blocking the drivers view (and intend to spend quite a bit of time testing to establish there is no false positives using this sensor for the frunk with a backup strap to make sure the frunk won't fly open if popped by some rock or road debris moving across the sensor at the right time) -

    But right now need to find a source of 12v power that would turn off the sensor when the car is locked.

    Might anyone have done the testing and can advise, or perhaps have the wiring diagram for the Model 3 they could share?
     
  2. M109Rider

    M109Rider Active Member

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    I believe there are a few companies making kick sensor units for the model 3. (I think).
    If I was working on a new kick sensor, I would find out which wires the current kick sensor packages use, and go from there.
     
  3. Garlan Garner

    Garlan Garner Banned

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    #3 Garlan Garner, Oct 26, 2019
    Last edited: Oct 26, 2019
    1.You will be in need of a CAN bus reader ( Arduino ) with a power relay on one of the outputs.


    2/Or.. you can power your foot sensor off the battery but activate it off the Solenoid release request wire on the left side of the radiator under the frunk. That will allow your foot sensor to act identically to frunk release button on the screen.
    That's how the electric frunk release works. Model 3 Electric Frunk – Tesla Offer

    CAUTION: if you ever short out that frunk release request wire.....your MPU might get damaged...and they aren't cheap to replace. I have a buddy who did that and when you damage an MPU...tesla will know and won't cover it via warranty.
    I have a buddy who did that moding his model 3.

    I went with option 1 because I'm very familiar with Arduinos and the CAN bus. Its tremendously cheaper and easier to install.
    All I'm doing is inserting the screens frunk open request message onto the CAN bus when the sensor is read by the interrupt pin on the Arduino.
     
  4. megabyte

    megabyte Member

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    Hi M109Rider, Sorry, seems I wasn't clear enough. I am not reinventing the wheel. The testing I am doing is with one of those commercially available kick sensors that is designed (though it is all passive, so I use that word loosely) to (using ultrasonics) pop the trunk. I have it working (as in swipe foot under frunk and get hood to unlatch, but before I could even get round to testing if there is false positives when driving, I realised that by powering it directly off the 12v battery (I understand the issues with doing this) and using the emergency release in the frunk, the kick sensor would pop the frunk while the car was locked.
     
  5. megabyte

    megabyte Member

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    Thanks for your reply Garlan Garner.

    I am familiar with Arduino, but haven't touched programming micro controllers since the PICAXE days ;) I have a friend who is well into them though, so should be able to get some help there.
    I presume that the "power relay connected to one of the outputs (any source of 12v power?)" to be the switching device that encodes the CAN bus signals at a higher voltage than the Arduino CAN bus board will output?

    Understand about activating the solenoid on the left hand side of the car, but I trust we are in agreeance I will then need to figure out voltage (though I trust will likely be 12v) and current required to drive it.

    I think I would prefer to skill up on the CAN bus option, as see this being more useful going forward, and works with the safety and security functionality of the car (which I trust includes not activating both trunk solenoids when car is being driven, or locked, like activating the left solenoid would still allow, right?). Could you point me to a source with CAN bus signals for the Model 3? I am not sure if there are standard signals across all manufacturers, but I would imagine Tesla's somewhat unique frunk commands won't be detailed everywhere.

    Finally, could you give me some idea of the cost for the MPU. Several hundred, several thousands? Will likely motivate me to stay on the cautious of playing around ;)
     

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