smart Keys

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Permalink Reply by Louis Bolieu on May 20, 2008 at 5:23pm

Neal, I just did this yesterday, got my wife on her cell phone, she clicked the unlock button on her spare key, and the Passion's doors unlocked. Tried it coming from the house's land line and it worked. Worked on our Dodge Caravan too. I don't know why it doesn't work for you
Louis

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Permalink Reply by neal on May 20, 2008 at 6:53pm

Thanks for clearing up the cell phone opening for smart. I will try it when I get it.

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Permalink Reply by jackb on June 2, 2008 at 12:09am

I am writing this reply immediately after reading Louis's posting, so I have not yet tried it out to see what gives (current scientific thinking does not give much credence to the claimed power of magic wands, but it probably does no harm to wave one around now and then to see what happens).

This business of using a cell phone to relay an unlock command from a remote key makes no sense to me. What signal exactly would the door lock be receiving and executing? There are only two available media through which a signal could be transmitted...acoustic and electronic.

My car's key does not emit audible little squeaks when I press "unlock." In any event, I doubt that the smart's door locks have been equipped with acoustic sensors, just in case I lock my keys in the car (sort of like the old trick of using those whistles that used to come in boxes of Cap'n Crunch to generate a 2600 HZ tone that would disable the phone company's toll mechanism). And if they did go to the expense and technical trouble to install such a system, it would likely be triggered about 50 days a day from environmental noise in the human audible range. Using ultrasonics wouldn't work either, since phones are not hi-fi mechanisms and do not phonically reproduce stuff above 15K Hz or so (not sure of the exact cut off...it's probably more like 12K).

The alternative of using RF also does not seem to me to be viable. This would require either a grand conspiracy among the various producers of phone equipment and providers of voice/data transmission to encode a special signal for the purpose of unlocking car doors...and/or a common installation among vehicle manufacturers of systems in their door locking mechanisms that could read the subtle modulation of a cell phone's RF and interpret when a signal not intended for it "means" that a message is coming through to unlock the damn thing already. Compared to that, the SETI project looks like junior high school science.

So if this particular magic wand works (as you may have noticed by now, I have my doubts), can anyone explain the physics of it? Us liberal arts majors have a hard time with this stuff....

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Permalink Reply by Brad Waite on June 2, 2008 at 12:33pm

Oh, c'mon, JackB. Do you think anyone but a phreak would know that MF tones can be used to seize in-band signaling trunks? :)

But you're right, it's not using audible tones, although even if it did, it wouldn't be hard to engineer a combination that *doesn't* occur in nature.

Every remote key fob I have *ever* seen works via RF (radio frequency, for those that don't know). A quick google indicates US key fob frequency is 315MHz - utterly outside the vocoder range for any kind of cell phone. And, yes, it's completely beyond the realm of possibility that there are key fob transceivers built into cell phones.

I'm wondering whether the people that tried this trick did so from their homes when the cars were parked in the garage or driveway. If not, I'm completely stumped and think that it's PFM.

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Permalink Reply by jackb on June 2, 2008 at 2:36pm

Yeah, but now that everything is pretty much exclusively out-of-band, talking about in-band signalling to mess with call routing switches is sort of like discussing the finer points of COBOL. After they run off to look it up in the history books, they begin to wonder if you were sad when you saw all the dinosaurs dying off. Oh well...

As to the business with unlocking your car door by putting your phaser on stun, I think you're right...it sounds like pure (present participle) magic.

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Permalink Reply by Dave on May 22, 2008 at 11:42am

Here's the straight skinny about the keys based on my 5 week quest to get additional keys. ALL smart OWNERS NEED TO BE AWARE OF THESE KEY FACTS:

1. There is only ONE type of key. It comes in two parts that are ordered and sold seperately - the metal "blade" and the plastic "remote/head." The "flat key" the dealer was getting me was the "blade." There is NO "VALET" (or any other) KEY AVAILABLE that can be used to start the car.
2. The key "blade" must be ordered, "cut" by smart (not the dealer), and takes 3-6 days to get.
3. There is a computer chip in the key "remote/head" that sends a signal to the car's immobilizer system that enables the key to start the car. This chip IS NOT powered by the "remote/head" battery as the car will start even with the battery removed.
4. The car MUST be "coded" to all the keys that are to be used to start the car. If you get a replacement or additional key, ALL the keys must be coded/recoded to the car for them to work. You CANNOT START THE CAR with a key that has not been coded to the car.
5. In order for a dealer to code or recode a key(s) they must get a 12 digit code directly from smart. This code is good for 5 days only and IT TAKES 24 HOURS TO GET THE CODE FROM smart !!!!!!! (?)

NOTE: If you misplace one of your smart keys, you MUST HAVE THE OTHER in order to start the car. NOBODY CAN START IT ANY OTHER WAY. If you don't have access to the other key (e.g. spouse out of town), you're out of luck! And you are 3-7 days, a trip (ot tow) to the dealership, and an expensive service bill away from getting going again. Unless you keep your second key at home, I strongly suggest that you seriously consider getting a third (& fourth?) key. And read all the sections of your Owner's Manual dealing with the keys, especially the part about locking the car without the Remote. As the old saying goes ... YOU HAVE BEEN WARNED. Good luck.

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Permalink Reply by Not so smart on May 22, 2008 at 12:35pm

I am just wondering, how does the car battery power up the chip or read the chip in the key "remote/head" if the chip isn't getting power from the "remote/head" battery ? Maybe the "remote/head circuit board has a capacitor that holds power to the chip circuit for sometime after the battery is removed. Also I saw a kit somewhere that talked about removing the lock cylinder and replacing it with a push button switch for the smart 451. In this case would you have to have the "remote/head" in the car with you in ordrer to start the car ?

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Permalink Reply by Dave on May 23, 2008 at 9:00am

The chip is not powered in any way. When you turn the key to the start position, the car's ECU (Computer) sends a signal to the key remote/head/chip to see if the chip's code matches those recorded (coded) in the ECU. In effect, this temporarily "powers" the chip although no power other than an electronic signal is involved. This "checking the chip code" explains the very slight delay from when you turn the key until the starter engages. Virtually every other manufacturer uses the same type of chip/coding/immobilizer security system today. However, most (all) other manufacturers (e.g. Honda, VW, BMW, Mercedes-Benz, etc) have a "Valet" key (no Remote) available that contains a chip that can be coded to enable it to start the car. None of these "Valet" keys/chips are powered. smart does not. WHY?

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Permalink Reply by Not so smart on May 23, 2008 at 12:29pm

Thanks Dave, I got it now. It's hard to say why this car just dosn't do everything like it's brand mate and most other cars with this chip security feature. Will the"valet" key that you got turn the ignition lock to the on and start possition or will it just unlock the door ? And if it will turn the lock to the start possition will the starter ingauge if the "remote/head" with the "blade" is in the car with you ? If it's in the car then the ECU should be able to read the chips code and the car shound start. I like the fact that this car has this feature. It makes me wonder if anyone needs to puchase the optional $160.00 Anti-theft system. It sounds like they allready have this covered. I mean if someone broke out the ignition lock and jumped the wires to on and then to start the ECU would not allow the car to crank and start because it could not find the chip to read. But all this dosen't help you with what you are trying to do unless the "valet" key with the "remote/head" in the car idea works. If this works then you could have the blade removed from one of your "remote/head"units and hide the "remote/head"only tn the car somewhere. Then you could start the car with all the "valet" keys you wanted. It would be very interesting to find out if this works.

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Permalink Reply by Dave on May 24, 2008 at 10:35am

Yes, the "valet" key, really a "blade" will unlock the door AND will turn the ignition switch to the Start position however, the car will not crank. If, on the other hand, you have a properly coded "remote/head" NEAR the ignition switch, the "blade" will start the car. As an emergency measure in case I should lose my key, I have duct taped a "blade" to the back of my front license plate and hidden my spare key with "blade" and "remote/head" inside the car. This way even if a thief discovered my "blade" taped to the back of the license, he/she still couldn't start the car.

Another interesting note. While both a full key and a "blade" only will unlock the driver's door using the key lock mechanism, NEITHER will lock the car using that mechanism unless you follow the rather complex procedure outlined in you owner's manual. I suggest that every smart owner become familiar with this procedure BEFORE the need arises.

My final observation to all is: If I had lost both of the keys to my smart, I would have been 9 days, a 75 mile towing charge, and a significant dealership key coding service charge away from getting back on the road. As they say, YOU HAVE BEEN WARNED!

Make it a great day and enjoy your smart.

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Permalink Reply by mr bad example on May 24, 2008 at 12:36pm

very interesting and educational, for the last 25 years i've kept spare car and house keys in my wallet "just in case". i think i'll keep my second key hidden in my smart and invest in a couple of "blades", that would be the most workable "compromise" (and also economical)

so it looks like i blew $160 for a useless alarm (almost).

thanks for the info Dave!

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Permalink Reply by Not so smart on May 24, 2008 at 12:15pm

Hi Dave, I'm glade this works. It's to bad thought that you have to keep your complete second key in the car all the time for emergencys. But this is the only way to keep from getting stuck somewhere. Even if you spent another $165.00 + on a new complete key, it can't help if it's at home and your 600 miles away. It's good to know that the "remote/head" must be near the ignition switch for the "valet" key to crank the car and start it. Not just anywhere in the car. When I get my smart, I will think hard about doing the same thing. As you said, we all HAVE BEEN WARNED!

This is good example of how a great security feature can get tripped up by one small design change

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