Pat8635

My first attempt to post here was ugly ... But after a few years will try again. I have searched for this using both google and your internal search engine and can't find an answer. I am missing a key fob and figure there has to be a way to create or buy a gadget to find it. Why, because when fob gets close to the car the lights come on, so it senses its presence ... So there has to be a way to find what drawer or suitcase or cushion it fell into or under or where the dog hid it using that feature... And no house isn't big enough to push car through...

Thanks!

skywise

Here's the main article on keyfobs from wiki
http://en.wikipedia.org/wiki/Remote_keyless_system
The freq they tend to live on is 315Mhz.
Now, what I don't know is how often or for how long the key chirps, I'm guessing a very very short time.
(a data burst with it's ID pattern so the car can pick it up as being close)
So, I don't think something simple like a radio at 315Mhz will do it, transmission time would be too short for a human to detect.
Other than that, I don't think there's anything generic out there.
If I HAD to find the fob no matter what, maybe find a dead Lexus with the same system and pull the parts related to the keyless entry system? Even then, it probably would ignore a keyfob that isn't programmed into it.
Although.. A simple computer(ardurio) hooked to a software radio, detecting the carrier freq of the fob.. Alot of fiddling and would need a good directional antenna to keep the thing from detecting all the other 315Mhz stuff out there..

Pat8635

That helps...I have some radio geek friends...And the idea of one of those scanners from a phone app is really good..

Thanks!

PS...much better than my first attempt here!

Dave Mac

I used to have a frequency counter (kind of looked liked something Ghost Busters might have used) that would pick up anything transmitting in the immediate area. So since you probably know the frequency you are looking for something like that would work. The problem is it probably cost about as much as a new key fob. I sold it on ebay for I don't remember what but I bet it was far less than $50. You might check and see if anything like that is listed.

And good luck.

Dave Mac

Pat8635

With some research I found out that 315MHZ is cable channel 39. I checked with my TV's tuner and found that it broadcasts on that frequency, but there are no pulses that would account for car knowing proximity, so I am guessing that there is an rfid that lets the car know that it is close. Now, how to find that!

jcicero

Has anyone found a way to find a list key yet? Just lost my key today and think it's in my house somewhere, really bad timing with Christmas...

TheAirman

The problem with all this is, usually the key waits until it is interrogated by the car before it send out a signal. And they might operate at 315 mhz, but each key has a rolling code built into it so each time you use the key, the code changes. Usually there is no 315 signal to search for unless you could carry the car around the house.

When you lose a smart key, the only thing you'll find, is a very big bill in the mail from the credit card company.