E53 key programming - strange problem

[wedgeman]

Originally Posted by dgtal

I'm going thru the same process before I throw away $170 for a new "useless" key that won't start the engine. I don't think there are 2 separate circuits and the large battery will never get charged if there is not physical path between the metal part of the key and the PCB. The circuitry is isolated from the outside world. I don't see any "imbeded" chip in any part of the key. I checked for transmission of signals off the air, nothing, just when I press one of the bottoms (luck/unluck/back door). So I still wondering if that will fix my problem.

I believe you're wrong here.. there is no circuit between the rod of the key and the PCB. I've had many of these keys apart numerous times (I"m now doing battery replacement for folks and a local dealership).

The ignition assembly has an electromagnet which fires whenever the key is in and ignition set to 'run'. IN the key is a small coil/magnet assembly which in turns charges the circuit for the security assembly. This in turn fires back an electronic code to the engine. That's the extent of my knowledge on this.

There are two or three embedded circuit chips on the PCB, and any one of them could contain a bit of a signal code, enough to do the job. i don't have one handy or I'd show you (i'm at home tonight, and have my own keys closed up again). But i"m certain that at least in this instance, the information is accurate -- it does have a signal bit which is charged by the ignition and which in turn throws out a signal to the starter security circuit.

Another method to prove this is the fact that for a year after my batteries died (Before I got the nuts to figure out how to open these things), I was able to use both my own key and my wife's key to run the car, even though the battery was so dead it wouldn't open the doors. In addition, you could stick it in and it'd start, but even when running the car, the battery was too dead to lock/unlock/etc....

hope that clarifies things....