Detroit Diesel Electronic Control (Ddec) - PREVOST Le Mirage XL Owner's Manual

Detroit Diesel Electronic Con-
trol (DDEC)
The major components of DDEC are as follows:
DDEC is an advanced technology electronic fuel
injection and control system for Detroit Diesel
engines. As an integral part of the engine, the
DDEC system provides a number of perfor-
mance features and driver benefits, including
improved fuel economy and performance, re-
duced cold smoke, reduced maintenance and
repair cost. These advantages are obtained by
optimizing control of the critical engine functions
which affect fuel economy, engine reliability and
the performance of the injectors.
Its major components include an Electronic Con-
trol Module (ECM), Electronic Unit Injectors
STARTING AND STOPPING PROCEDURES
(EUI) and sensors. The ECM is the brain of the
DDEC system and is located between primary
and secondary fuel filters. Within the ECM is the
Electrically Erasable, Programmable, Read Only
Memory (EEPROM) that provides instructions for
basic engine control functions such as rated
speed and power, engine governing, cold start
logic and diagnostics, plus an engine protection
system.
The ECM continuously monitors and analyses
the DDEC system during engine operation with
electronic sensors. The Electronic Unit Injectors
(EUI) operate on a principle similar to the me-
chanical unit injector system. However, a sole-
noid-operated control valve performs the injec-
tion timing and metering functions which make
injector timing much simpler and more precise.
DDEC provides the capability to quickly diagnose
system malfunctions by a self-diagnostic system;
the self-diagnostic system monitors all engine
sensors and electronic components and recog-
nizes system faults and other engine-related
problems by providing the technician with a di-
agnostic code. Diagnostic codes are logged into
the ECM memory and can be read by performing
procedure outlined on page 5-7.
Engine Brake System (Jacobs)
The "Jake brake" is a diesel engine retarder that
uses the engine itself to aid in slowing and con-
trolling the vehicle. When activated, the "Jake
brake" alters the operation of the engine's ex-
haust valves so that the engine works as a pow-
er-absorbing air compressor.
retarding action to the wheels.
The engine brake is a vehicle-slowing device,
not a vehicle-stopping device. It is not a substi-
tute for the service braking system. The vehi-
01015M
cle's service brakes must be used to bring the
vehicle to a complete stop.
Effectiveness of the engine brake system will
vary according to transmission gear in use. The
engine brake system is more effective in lower
gears and at higher engine speeds.
Warning:
grades, use service brakes as little as possible.
If engine does not slow vehicle to a safe speed,
apply service brakes and shift to a lower gear.
Let the engine (and engine brake) retard the ve-
hicle. Keep brakes cool and ready for emergen-
cy stopping.
4 - 3
This provides a
When descending significant