Engine Control Module: Description and Operation

The ECM is a precision unit consisting of a one chip microcomputer, A/D (Analog/Digital) converter, I/O (Input/Output) unit, ROM (Read Only Memory) and RAM (Random Access Memory). It is an essential part of the electronic control system, its functions include major functions, as to control the fuel injector, ISC solenoid valve, fuel pump relay, etc.

The ECM diagnoses troubles which may occur in the system when the ignition switch is "ON" and the engine is running. It indicates the result by turning on or flashing the "MALFUNCTION INDICATOR LAMP" when a fault occurs in any of the following systems:

^ Oxygen Sensor.

^ Coolant Temperature Sensor.

^ Throttle Switch (M/T model) or Throttle Position Sensor (A/T model).

^ Manifold Air Temperature Sensor.

^ Pressure Sensor.

^ Ignition Signal.

^ Crank Angle Sensor.

^ Vehicle Speed Sensor.

^ EGR system.

^ CPU (Central Processing Unit) of the ECM.