Engine Control Module (ECM) (Engine management system - EDC)

The input from the sensors constantly updates the ECM with the current operating condition of the engine. Once the ECM has compared current information with map information within its memory, the ECM can make any required adjustment to the operation of the engine via the following actuators: l EGR modulator. l Glow-plug relay. l Fuel pressure regulator valve. l Electronic fuel injectors. l Cooling fan relay. l A/C compressor clutch relay. l Vacuum control module

The ECM also communicates with other systems on the vehicle, both receiving information used to influence fuelling and transmitting information of importance to the other systems.

The systems are as follows: l ABS ECU. l Electronic Automatic Transmission (EAT) ECU. AUTOMATIC GEARBOX - JATCO, DESCRIPTION AND OPERATION, Description. l Glow-plug relay. l Instrument pack. INSTRUMENTS, DESCRIPTION AND OPERATION, Description. l Immobilisation ECU. SECURITY, DESCRIPTION AND OPERATION, Description. l Cruise control interface ECU. ENGINE MANAGEMENT SYSTEM - EDC, DESCRIPTION AND OPERATION, Description.

Engine Control Module (ECM)

The ECM has a steel casing to provide protection from electromagnetic radiation and is located in the E-box.

The ECM contains data processors and memory microchips. The output signals to actuators are in the form of earth paths provided by driver circuits contained within the casing. The ECM driver circuits produce heat during normal operation and dissipate this heat via the casing. The airflow around the ECM should not be obstructed. There are regulated voltage outputs to some sensors which use less than 12 volts to avoid voltage drop during engine cranking.

The ECM cannot be tested directly, diagnosis must be performed by ensuring that inputs and outputs conform to specifications. TestBook is available for this purpose. If the ECM is to be replaced, the new ECM will be supplied 'blank' and must be configured to the vehicle using TestBook. When the ECM is fitted to the vehicle it must also be synchronised to the immobilisation ECU using TestBook. Engine control modules cannot be swapped between vehicles.