The OEM sensors on some early-model Ford/Chrysler vehicles with TPMS (2002-10MY, OE sensors made by Schrader) are activated magnetically.
Chrysler 300M, Concorde, Crossfire
Dodge Intrepid & Viper
Some sources direct technicians to place a magnet on the sensor’s stem, to activate it during the relearn procedure. But the systems also support activation via LF signal so techs can use a TPMS tool to trigger the OEM sensors or Alligator sens.it sensors for the relearn.