DDEC TROUBLESHOOTING
2.3
DDEC SYSTEM--HOW IT WORKS
The major components of the DDEC system consist of the electronic control module (ECM),
the electronic unit injectors (EUI) and the various system sensors. The purpose of the sensors is
to provide information to the ECM regarding various engine performance characteristics. The
information sent to the ECM is used to instantaneously regulate engine and vehicle performance.
2.3.1
Electronic Unit Injector
An electronic unit injector incorporates a solenoid operated poppet valve which performs the
injection timing and metering functions. When the solenoid valve is closed, pressurization and
fuel injection is initiated. Opening the solenoid valve releases injection pressure, ending injection.
The duration of valve closure determines the quantity of fuel injected. See Figure 2-1.
Figure 2-1
Electronic Unit Injector
2.3.2
Electrical Connectors
Provide water-tight connections for the harnesses between the sensors and the ECM.
All information subject to change without notice.
6SE497 9709 Copyright © 1997 DETROIT DIESEL CORPORATION
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