Theory Of Operation
WARNING: This page is about a different car, the 2017 Jeep Cherokee. However, it is still accessible from the selected car via links, so may be relevant.
The Powertrain Control Module (PCM) stores a copy of the vehicle's module build configuration in its EEPROM. If the stored information in the PCM does not match the information sent over by the Body Control Module (BCM) of what modules are active on the Controlled Area Network (CAN) Bus, the DTC will set.