Computers and Control Systems: Description and Operation

DESCRIPTION AND OPERATION
The Multiport Fuel Injection System consists of sensors which detect the engine conditions, the ENGINE CONTROL MODULE (ECM) which controls the system based on signals from these sensors, and actuators which operate under the control of the ECM.
The ECM carries out activities such as fuel injection control, idle air control and ignition timing control.
In addition, the ECM is equipped with several diagnostic test modes which simplify troubleshooting when a problem develops.

DIAGNOSTIC TEST MODE
- When an abnormality is detected in one of the sensors or actuators related to emission control, the SERVICE ENGINE SOON/MALFUNCTION INDICATOR LAMP illuminates as a warning to the driver.
- When an abnormality is detected in one of the sensors or actuators, a diagnostic trouble code corresponding to the abnormality is output.
- The RAM data inside the ECM that is related to the sensors and actuators can be read by means of the scan tool.
In addition, the actuators can be controlled under certain circumstances.