FWIW, Chrysler has used magnets to trigger the sensor from the beginning. I have the actual Chrysler magnet that I used when reprogramming my 2002 Chrysler Town and Country Limited to recognize new sensors. I believe, but do not know for a fact that the system that Chrysler used originated from the Prowler with its lack of a spare tire, and they added also to the high end maxed out T&C Limited and Jeep Grand Cherokee Limited.