Lost keyfob, any way to locate it using RF signals?

I know both of my keys are in the house somewhere.. unfortunately I can only find one. I'm hoping the dog didn't eat the other.

Does anyone have any knowledge of the interaction between the car and they key fob that activates the walk up unlock? I figured it was the car sending out a "ping" for the key fob to sent an unlock signal back and when the car heard the key fob reply to that "ping" it would unlock and present the door handles.

I'm guessing the key fobs aren't programmed themselves, that the car is configured to only unlock for specific keys. therefor, I figure there is a way to get a key to send out the reply "i'm here" signal and use a very directional antenna to try to locate that signal.

Hey, its a fun project, and worth trying for the $500 cost to replace a key.

wk057 said:

I guess you could extend the FOB antenna temporarily and wander with it... that'd be interesting...

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that would be doable, and not all that hard.

On the other hand, part of the reason for the method I asked about is to get more info about the process. I'm frustrated with how we get no info about how the car works from tesla (no service manuals most importantly).

Even if I purchase the extended warranty, I'm only going to have 2 more years at most of being under warranty coverage (at 44.3k now in 14 months of ownership). I need info on how to properly service the vehicle. According to the logs, I have a charger that might be offline (only getting 40a charge rates right now), How can I diagnose which charger is kaput, program it and install? That info needs to become available.

Chris TX said:

LOL! I proposed that exact solution last year for someone that lost their fob. Someone would stand near the car, waiting to see the handles present when the antenna was waved near the lost fob. I bet a temporary Cat5e solution would work.

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the best solution would be a coax to a .905 meter antenna, (or 1/4 or 1/2 of that length) to wave around. Either way, if playing with my SDR doesn't yield something useful for doing this I will be running around with a lot of coax to find the damn key.