PCM (Powertrain Control Module)

The PCM/ECM carries out a check of the ignition key using a special encryption algorithm, which is programmed into the transponder as well as the PCM/ECM simultaneously. Only if the results are equal, the engine can be started. The data of all transponders, which are valid for the vehicle, are stored in the PCM/ECM.

Fig 1: Identifying Power Train Control Module
Courtesy of KIA MOTORS AMERICA, INC.