Unlocking your car with a cell phone?

[Jeremy airjer W]

Along with our paychecks we received a piece of literature with cell phone tips and tricks. One of them was how to use you cell phone to unlock the car. It sounded like a sham but we tried it out on a Dodge Dakota and sure enough it worked.

There are a couple of conditions for this to work. Your vehicle must have keyless entry, both people have to be on a cell phone, and the other person needs to have a spare FOB (keless entry remote). If your keys are locked in the car simple call the person's cell phone that has the spare FOB. Have them hold the FOB next to there phone and press the unlock button while you are holding your phone near the drivers window of the locked vehicle. The door should unlock.

when I read this I was thinking the same thing you are, NO WAY. Seriously, last night we unlocked and locked the Dakota several times from our business office.

Give it a try and post your results!

[Shack]

Trouthunter,

I tried, as best as I could. I gave the my best idea at least. If you read back, you will find my post.

I will repost under here what I "thought":

To put this into prospective, I have an older dial radio (tuned in on AM) sitting on the ledge of the window behind me in my office. It is always turned on, but the volume is turned down. I know 5-10 seconds before my cell phone rings that a call is coming in. My radio clicks and pops. It keeps clicking and popping while the phone is in use. Basically, the radio is in between (in the area) of the wireless signal coming into my office (this could be construed as the module in the car/truck) to my cell phone. I guess I should correct my self and say the signal is not going into the receiving phone and then out to the car/truck, but rather the car/truck is in the inbound lane of the incoming wireless signal. The wireless signal going into you cell phone is not just a narrow beam signal, I believe it is wide spread to make sure it finds your little cell phone. The vehicle just happens to be in the wide beam coming down or at the phone.

I feel the same is for the transmitting end phone. When the button is pressed on the fob, a wide wireless signal/frequency is blasted in every direction in a circle type patter looking for a receiver or a receiver path (in a parking lot, when you hit the panic button to find your car, you do not have to point the fob right at you car). It finds the out going signal transmitting up and away from the phone. I do not believe the remote fob signal goes into the phone and then out, but rather meets up with out going signal from phone and threw the sky and passes into a Chrysler remote module.

At least "I" tried to give a theory.

Some higer up(s) in this forum said it works, I have seen it work, but will see what happens.

Limitout did give a good explanation of why it would not work and I did make a correction for this. I missed his post.

[Shack]

Deadhead,

I questioned this, because on late model (lets say 1996 on up) you can add up to 4 or 5 different personal codes. To erase your personal code, you would have to punch the factory code in and hit the 1/2 button, enter another 5 digit code and start that process over 4-5 different times. It would be impossible, unless the battery was disconnected for a period of time. I guess with kids, nothing is impossible .

What I know of the personal code’s, if you fill up the allotted amount of personal codes, it startes the newest by erasing the oldest. I have never tried this in person, but I have come to believe this is true. I could be wrong.

[DEADhead]

shackbash, thanks for the info, I didn;t know you could put in more than one personal code.

 Quote:

It's like saying I passed someone a ham sandwich through the phone

funny stuff. So far I haven't heard any cases where this would work on a Ford vehicle. And only sometimes on late model dodges. Why are only certain people able to get this work on a dodge, while other's aren't?

[Macgyver55]

 Quote:

Why are only certain people able to get this work on a dodge, while other's aren't?

They're standing closer!

[doughnut03]

"There was even a guy that claimed to work for a cell phone company and all he said was “it is a hoax”, with out any explanation as to why it would not work. It’s like bringing in a car with a concern to a dealership and having the technician tell you “it’s broke”, with out explaining why “it’s broke”."

So here it is...

Key FOBS operating bandwith:

France: 224.5mhz

Italy, Australia, Japan, Canada and the USA: 315mhz

UK and Ireland: 418mhz

Europe: 433.9mhz

Cell Phone operating bandwith:

In the US, TDMA was found primarily on 800 MHz and 1900 MHz

In the US, CDMA uses the standard 800MHz and 1900MHz.

In the US, GSM mainly operates on 1900MHz.

With a cell phone, packets of data are sent randomly across the width of the channel and reassembled by the network at the other end so the bandwith basically jumps around all over the place.

IT DOESN'T WORK BECAUSE THEY OPERATE ON COMPLETELY BANDWITHS. LIKE TRYING TO LISTENING TO FM RADIO ON THE AM SETTING.

[cylinder]

I don't think it matters that the key fob and cellphone broadcast on different frequencies-- if it did, there would also be a problem with human voice (at roughly a few hundred hertz)on the cellphone channel. What does matter is that the microphone and speaker of the cellphone aren't made to pick up or reproduce the fob's frequency.

As a previous poster said, even the highest quality speakers in a home stereo have a limit of around 16hz-20khz; a cellphone speaker's range is much less than that because it is optimized for human voice. It isn't able to reproduce frequencies in the range of 300 mhz.

[Surface Tension]

I haven't tried the cell phone experiment. To do so I'd have to incorporate my wifes help. I don't need that aggravation.

I'm going to try a silent dog whistle in private. That way if it doesn't work no one will know but me.

[Scott K]

" I haven't tried the cell phone experiment. To do so I'd have to incorporate my wifes help. I don't need that aggravation."

So true!! I thought about giving this a try , but then I would need to explain to my wife why I was doing it, and where I heard of it, then she would tell me that I waste way to much of my time on the fishing site! And that isnt true!