Originally Posted by
onehundred80
The way I see it is:
The secret of the key working is the chip in the fob. Each chip is coded to match the info locked into one particular cars memory. The chips access to the cars coding is via the transponder (halo) ring around the ignition key hole.
The physical key is matched to the cars tumblers in the ignition, and door locks etc.
The transmitters in each fob are all the same but are individually matched to the code required by that particular cars receiver to open or close the locks. This info is learned when the matching process is done for the first time or when new batteries are installed in the fob when too much time has elapsed and the memory of the fob is lost.
I imagine you could have an infinite number of keys made for a particular car as long as each chip was encoded with the associated VIN info and the physical keys were cut all the same. Every key that works on your car is a clone.
The physical keys appear to be cut with an end mill type cutter, they even show the machining marks, no laser cutting at all. Dealers like adding hi-tech words to their sales pitch, it makes the customer happier to spend their money.
This is what I imagine it to be, if I am wrong somewhere let me know.
You are close.
The security is two parts, the fob and a special code key in the skreem, think of it as the fob having the first 6 digits of a password and the skreem having the last 6. Together they make up a code via some algorithm that delivers the real code. So each fob has a different id code that needs to be learned. The system can't be expected to hold an unlimited number of fobs in memory so they limit that and cycle them through based on learned history. Cloning would be the answer because the car would not know the difference.