PCM (Power Train Control Module)

WARNING: This page is about a different car, the 2014 Hyundai Elantra GT and 2013 Hyundai Elantra GT. However, it is still accessible from the selected car via links, so may be relevant.

The PCM (ECM) (A) 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).
ERN (Encrypted Randorm Number) value between EMS and encrypted smartra unit is checked and the validity of coded key is decided by EMS.

Fig 1: Identifying Engine Control Module (ECM)
Courtesy of HYUNDAI MOTOR AMERICA