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| Illustration 1 | g00928978 |
(1) Primary ECM | |
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| Illustration 2 | g00928980 |
(2) Secondary ECM | |
The engine uses two Electronic Control Modules for normal engine operation. The Primary ECM and the Secondary ECM control the engine. The modules communicate over a data link. If the Primary ECM fails the Secondary ECM will take over control of the fuel injectors. Engine monitoring from the Primary ECM will be lost until the ECM recovers.
The ECM supplies signals to the Electronic Fuel Injectors. The ECM signals control the engine operation. The ECM consists of two main components, the control computer (hardware) and the Personality Module (software). The control computer consists of a microprocessor and electronic circuitry. The Personality Module is the software for the control computer which contains operating maps that define power and torque curves.
The primary ECM is cooled by fuel as the fuel circulates through a manifold. The manifold is inside the control module.
The personality module consists of the following items.
- The personality module has all of the software and instructions for the ECM. Updating the personality module to a different version may cause some changes. Some of the characteristics of the engine operation may behave differently.
- A control map defines the fuel rate, the timing, and other similar values. These values are defined for various operating conditions in order to achieve the optimum engine performance and fuel consumption. These values are programmed into the personality module at the factory.
The ECM consists of the following items.
- The ECM has a microprocessor that is used to perform computing functions. The microprocessor is necessary for the ECM to execute functions such as governing, injection timing control, system diagnostics, and data link communications. The microprocessor receives instructions from the software that is stored in the personality module.
- The ECM has a permanent memory that is used to store programmable parameters and diagnostic codes.
- Input circuits filter electrical noise from the sensor signals. Input circuits protect the internal circuits of the ECM from potentially damaging voltage levels.
- Output circuits provide the high currents that are necessary to energize the injector solenoids, the lamps, and the relay.
- Power circuits provide high voltage for the injector solenoids. Power circuits clean stable electrical power for the internal circuits and the external sensors.