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

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

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