[Fat Charlie]

I'm only a parts guy, but here's my basic understanding: The TPMS module recieves signals on a specific frequency and simply registers the fact that it's getting signals from four different sensors and that means everything's happy. When one sensor gets unhappy or fails, the tire light comes on. A new TPMS sensor is registered to a vehicle by installing it and driving around a while. The car eventually accepts that one of the four it was used to is gone and logs the new sensor as being proper.

While getting into a system through an unsecured wireless connection is tempting, I think this would be just about as useful a way to take over a car as tapping into the wire from the oil pressure switch. You would now have the power to turn on someone's oil light at will- Muahahaha! Being able to do that wirelessly would be more convenient than tapping a wire, but I can't see what you would do with it- overwhelm the TPMS module?