The PCM is activated by power supply. Signals from several sensors, such as CKPS and APS, is inputted to PCM. Comparing inputted siganals with control LOGIC are saved at micro controller and EEPROM, the PCM controls engine as actuating injectors, solenoids and relays.

To guarantee accurate control, the PCM performs SELF TEST, DIAGNOSIS of several sensors and actuators. If serious trouble which affects vehicle performance occurrs, the PCM sets DTCs.

At certain cases, the PCM shuts down whole systems in order to prevent dangerous situation due to incorrect control.