The Keep Alive Memory (KAM) allows the vehicle’s control modules to store data related to the vehicle’s operation. The KAMA works even when the vehicle is off or the battery power is briefly interrupted. Once the ignition switch is turned on, power is delivered to the PCM. After that, a series of self-tests are performed on the controllers through the Controller Area Network (CAN). The signals from each module are compared. Also, the interaction between them is checked.
The DTC P0620 OBD2 is set because the PCM has detected the generator or alternator control circuit has experienced an error in its operation. The PCM supplies energy to the generator while the vehicle’s engine is running.