This will be a geeky post as well as long, OOHH where do I start?
First, it is possible the 450 keys and the 451 keys are made the same (just a GUESS on my part) so what has been discovered today may help the 451 owners as well and expose me to a wrist slapping.
Let’s start with the FOB, http://www.atmel.com/dyn/resources/p...ts/doc4591.pdf
this is the brains of the remote and MUCH to my surprise is very complicated and does much more that I ever expected. This remote does 2 things and could fail in 2 ways, 1st it is a remote for unlocking the car and 2nd it is an RFID (Radio Frequency Identification chip), OOHH and is programmable.
As a remote I don’t believe it is as complicated as the “How Stuff Works” post I did this morning, and nothing I have read in the application notes suggest the key word rolls, but a long keyword it is and I have not read everything as of yet.
As an RFID it too isn’t super complicated but putting both together is a **** buster. Some may wonder what an RFID chip is and how it works, well we see and use them every day. Anyone have a pet? When you go to the vet and they take that wand and pass it over the neck it activates that RFID chip (the magnetic field of the wand as it passes over the chip induces a voltage giving the chip power to transmit the pet’s serial number)? Anyone work at a company where your ID badge is swiped over something to unlock a door? Well there is a RFID chip in that badge. There is the same kind of chip in the FOB as well.
So the 2 failures you could see are 1: doors don’t unlock (failure of the remote portion of that FOB) or 2: you’re able to unlock the doors but the car doesn’t start (failure of the RFID part of the FOB)
By reading the application sheets I found this is the receiver for the remote/RFID combo Atmel Products - Product Card
that is in the car somewhere (maybe in the SAM unit or in this FQ101 : Smart Car Modifications
) and that too is programmable.
Now we come to the part where I speculate (guess), I have heard that you can’t order a Smart key unless you give a VIN#. I believe the VIN# you give is programmed as the RFID serial # (makes sense), then to get the key to lock/unlock that is where you need to go to the dealer (I’m not going to guess here because it could a few things new code/reset code/etc) to get the remote part activated.
Today both my keys work, but from what I’ve read this problem is only a matter of time and there is NO way I’ll let a 25K investment become a 1,600 pound paper weight, even if I have to buy the developers kit for these chips. AND if the 450 keys are the same as the 451 keys MB may want to rethink their snubbing of we gray owners because I LIKE TO SHARE