CKE7
Posts: 11
Joined: Tue Feb 05, 2019 12:42 pm
Location: Palm Springs, CA

Use car or BMW connect to find missing keyless entry fobs?

Sat May 25, 2019 8:02 pm

:ugeek: I think I need an uber geek for this one....I cannot find my main set of keys which holds my keyless entry fobs for my 2016 i3 REX and the 2018 X1. (I also have another set of fobs.) I don't know if I dropped the keys between the car and house, inside the house or -- worst case -- I left them in the house door lock and someone lifted them. If I don't find my keys soon, I expect I need to re-key everything.

OR -- THIS IS MY QUESTION: is there any way to get my cars to "call" to the remote if it happens to be inside my house or garage? Or a way to use the BMW connect to do that? You'd think if my remotes communicate with my cars, it may work the other direction? Or is this science fiction? Thanks. I continue to hunt.
New owner of 2016 i3 REX
Palm Springs, CA

CharonPDX
Posts: 117
Joined: Sat Jul 21, 2018 8:54 pm

Re: Use car or BMW connect to find missing keyless entry fobs?

Sat May 25, 2019 9:34 pm

Nope. The fobs have no speaker, so even if there was a way to initiate reverse communication, there's nothing you could do to make it findable.

Some cars have two-way key fobs with some sort of sound generator, but not the i3.

Look in to a Tile or similar to put on your key fob.

CKE7
Posts: 11
Joined: Tue Feb 05, 2019 12:42 pm
Location: Palm Springs, CA

Re: Use car or BMW connect to find missing keyless entry fobs?

Sun May 26, 2019 12:24 pm

CharonPDX: Interesting. Thanks.

And I just found the keys. :D In house, in the side of a box that I thought was sealed!!!

After I posted here I found an article on line that said "it's possible to build your own transmitter [to track the remote], but it would take a lot of time, money and engineering know how..." That author too suggested putting a tracker on the key rings. Which I am going to do.
New owner of 2016 i3 REX
Palm Springs, CA

vreihen
Posts: 125
Joined: Tue Apr 30, 2019 4:55 pm
Location: Orange County, NY (FN21vm)

Re: Use car or BMW connect to find missing keyless entry fobs?

Sun May 26, 2019 1:29 pm

I'm going to disagree with that article. You can build a receiver using a ~$20 USB SDR (software-defined radio) dongle and a notebook computer with some free software, and then walk around watching the frequency waterfall graph until you locate the missing key fob.

I have SDRs on Raspberry Pi computers grabbing my weather station sensor data, monitoring my alarm system wireless sensors, and even tracking overhead airplane locations via ADS-B. Others are using them to track ship movements in harbors, listen in on police radios, and even decode weather satellite images.....
2015 BMW i3 BEV, Giga World, Tech and Driving Assistant packages, 15K miles

alohart
Posts: 1686
Joined: Sat Nov 01, 2014 7:36 pm
Location: Honolulu, HI

Re: Use car or BMW connect to find missing keyless entry fobs?

Sun May 26, 2019 3:48 pm

vreihen wrote:
Sun May 26, 2019 1:29 pm
You can build a receiver using a ~$20 USB SDR (software-defined radio) dongle and a notebook computer with some free software, and then walk around watching the frequency waterfall graph until you locate the missing key fob.
Does a fob transmit continuously or must it receive a signal before it responds? I've left our i3 fobs in a drawer for up to 9 months without needing to replace their batteries which makes me think that a fob doesn't transmit continuously. If that's true, how would your SDR detect a fob?
Aloha,
Art

2014 BMW i3 Arravani Grey, Giga World, Tech + Driving Assist, Parking Assist, DC Fast Charging, JuiceBox EVSE

vreihen
Posts: 125
Joined: Tue Apr 30, 2019 4:55 pm
Location: Orange County, NY (FN21vm)

Re: Use car or BMW connect to find missing keyless entry fobs?

Sun May 26, 2019 5:13 pm

I ASSumed that it is sending out some sort of radio "ping" every few seconds, but it would prevent the use of a pure receiver to locate the missing key fob if it wasn't transmitting.

From reading way too many i3 CarFax reports during my search, I noticed that dealerships seemed to be replacing i3 key fob batteries at about the 3-year mark like clockwork. My late-2015 car had low battery warnings for both fobs when I picked it up, and I told the selling dealer not to bother replacing them because our dog's doggy door collar transmitter uses the same 2032 cells as the key fobs and I have a bulk supply at home. Considering that I routinely get 8-10 years out of the remote non-fob key batteries (all smaller than the 2032) in all of our other vehicles, I made the assumption that it was sending out periodic transmissions.....
2015 BMW i3 BEV, Giga World, Tech and Driving Assistant packages, 15K miles

alohart
Posts: 1686
Joined: Sat Nov 01, 2014 7:36 pm
Location: Honolulu, HI

Re: Use car or BMW connect to find missing keyless entry fobs?

Sun May 26, 2019 7:36 pm

vreihen wrote:
Sun May 26, 2019 5:13 pm
I ASSumed that it is sending out some sort of radio "ping" every few seconds, but it would prevent the use of a pure receiver to locate the missing key fob if it wasn't transmitting.
If I were designing fob logic, I don't know of any reason for it to transmit periodically. Maybe I'm missing something.

The fob doesn't care is its car is nearby, but a car with Comfort Access cares if its fob is nearby. Press a fob button and it transmits a relevant signal. The fob doesn't care if the car receives its signal and responds because the fob doesn't indicate car state. However, when the door handle of a Comfort Access car is touched appropriately, the car could transmit a signal asking the fob to send the credentials that would cause the car to unlock the door or hatch. If no or incorrect credentials are received, the car remains locked.

Maybe someone with fob programming experience could explain why periodic transmissions would be necessary.
Aloha,
Art

2014 BMW i3 Arravani Grey, Giga World, Tech + Driving Assist, Parking Assist, DC Fast Charging, JuiceBox EVSE

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