Tracking down a lost SKS key

Is there a way to get the Prius in your house? If so, you know you're near the key when the doors open. Then you've narrowed down the search.

Seriously, I've never heard of a way of tracking down a SKS. That sucks to misplace one. In the future you may want to have these RFID chips (or something to that effect) attached so that in the event you do misplace it, you can locate it with a special transmitter. I think Brookstone sold something like that.

 

If you know the oscillator frequency of the Prius and the SKS fob, you can build something that will send out a Prius challenge, and the fob will answer. It's quite possible that unless you have a lot of time on your hands, and easy access to the parts, it would be cheaper to just get a new fob

 

I predict that you will find the missing fob in the last place you look. That's where everything is found.

 

Ok, I have exactly the same situation. I am 95% sure i lost it in the house.

But instead of driving the car into the house:blink: i want to extend the sks antenna with a wire. I already found it works at a freq of 134.2 Mhz, So i will have to use coax for this.

Anyone know where antenna for the SKS is located? or if there are multiple what antenna is best reachable for someone like me who is not a car technician (for the i am near the car part of the system?)


CAR: prius II, european.

Because a 20 Meter coax cable is way less expensive than a 100+ euro replacement key.

 

The car transmits on 134.2 KHz. When the fob recognizes the car signal, it replys on 315 MHz.

I don't know if the car transmission is encrypted and/or varying. It may not be, in which case you just record the car signal and replay it. The normal range of the car transmission is about 3 feet. I suspect that a long piece of single conductor wire strung from one of the door oscillators would have a longer range, perhaps enough to trigger the keyfob reply from maybe 10 or 20 feet away.

The keyfob signal is certainly encrypted and varying. If you press the same button multiple times, it sends a different sequence each time. But you don't care what the keyfob says, only that it is saying something. So if you can get the keyfob triggered, then you'll need a 315 MHz receiver with a signal strength indicator. A directional antenna would be a real plus.

This all brings back memories of hidden transmitter hunts back when I was in high school. The most devilishly hidden transmitter was hooked up to a mile long chain link fence as an antenna (4 MHz signal). Absolutely terrible antenna, but direction finding equipment couldn't identify anything useful.

So you need a 315 MHz receiver with at least a signal level meter. Then an antenna extender from an oscillator on the car. Maybe use a 100 foot long single wire (or an ordinary extension cord), and take several loops of it around the oscillator at one end.

If you pull this off, you could get a free booth at Maker Faire to explain how you did it...

 

The keyfob is different for 2016, but I'd be surprised if the basic mechanism is any different. They probably tweaked the encryption to keep ahead of thieves. Maybe something to fight rebroadcast of the keyfob signal.

The car signal at 134.2 KHz can be detected on generally available radios at the second harmonic of 268.4 KHz. do not know what to use to listen to the keyfob signal of at about 315 MHz. Maybe just cannibalize a Toyota keyfob receiver.

 

Theoretically you should be able to rebroadcast the *car's* signal unchanged indefinitely and get a response from the SKS key because it won't have "heard" the original broadcast until it responds. The response won't be valid to unlock the car, but it should be enough to get it to wake up and transmit.