PREVOST LE MIRAGE XLII BUS SHELLS User Manual

Section 01: ENGINE
PA1553
4
2.1 ELECTRONIC CONTROL MODULE
The Electronic Control Module is mounted, on
the starter side of the engine (Fig. 2).
Considered the "Brain" of the DDEC V system, it
provides overall monitoring and control of the
engine. It does so by comparing input data from
the various sensors to a set of calibration data
stored in the EEPROM (Electrically Erasable,
Programmable, Read-Only Memory) within the
Electronic Control Module. After comparing the
input data with the calibration data, the ECM
sends high-current command pulses to the
Electronic Unit Injectors (EUI) to initiate fuel
injection. The ECM also receives feedback
regarding the start and end of injection for a
given cylinder. The EEPROM within the
Electronic Control Module is factory
programmed by Detroit Diesel. Reprogramming
must be done at a Detroit Diesel authorized
service center. However, some changes may be
performed to the cruise control and road speed
limiter using a diagnostic data reader (see
paragraph "DDEC V Diagnostic Codes" in this
section).
FIGURE 2: ELECTRONIC CONTROL MODULE (ECM)01145
2.2 N3 ELECTRONIC UNIT INJECTOR
The N3 Electronic Unit Injector (EUI) is a
compact device that injects diesel fuel directly
into the combustion chamber (Fig. 3). The
amount of fuel injected and injection timing is
determined by the Electronic Control Module
(ECM). The ECM sends a command pulse,
which activates the injector solenoid. The EUI
performs four functions:
o Creates the high-fuel pressure required for
efficient injection;
o Meters and injects the exact amount of fuel
required to handle the load;
o Atomizes the fuel for mixing with the air in
the combustion chamber;
o Permits continuous fuel flow for component
cooling.
FIGURE 3: UNIT INJECTOR CROSS SECTION 01146
2.3 VPOD
There is one air-operated Variable Pressure
Output Device (VPOD) that controls the Variable
Geometry Turbo (VGT). The location of the
VPOD is to the left of the engine oil filters (Fig.
4). Pneumatic system supplies air pressure.
FIGURE 4: VPOD LOCATION 01149

PREVOST LE MIRAGE XLII BUS SHELLS Specifications

General

Brand	PREVOST
Model	LE MIRAGE XLII BUS SHELLS
Category	Buses
Language	English