User's Manual

Section 01: ENGINE
PA1561 19
2.5 PREVOST INSTALLED SENSORS
Engine Coolant Level Sensor (ECL
Sensor): Senses coolant level for engine
protection (mounted on coolant surge tank).
Turbo Compressor In Temperature
Sensor: Senses the air temperature at the
turbo compressor inlet.
Vehicle Speed Sensor (VSS): Provides a
vehicle speed signal (connected to
transmission).
2.6 MOTOR CONTROL MODULE (MCM)
The Motor Control Module is mounted, on the
starter side of the engine (Fig. 13). Considered
the "Brain" of the DDEC VI 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
Motor Control Module. After comparing the
input data with the calibration data, the MCM
sends high-current command pulses to the
Electronic Unit Injectors (EUI) to initiate fuel
injection. The MCM also receives feedback
regarding the start and end of injection for a
given cylinder. The EEPROM within the Motor
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
VI Diagnostic Codes" in this section).
FIGURE 13: MOTOR CONTROL MODULE (MCM)
01145
2.7 COMMON POWERTRAIN CONTROLLER
(CPC)
The CPC is the interface between the MCM and
the vehicle/equipment for engine control and
manages other vehicle/equipment functions.
Within the CPC, sets of data for specific
applications are stored. These include idle
speed, maximum running speed, and speed
limitation. Customer programmable parameters
are also stored here. The CPC receives data
from the operator (accelerator pedal position,
switches and various sensors) and other
electronic control units. From this data,
instructions are computed for controlling the
engine and transmitted to the MCM via the
proprietary data link.
FIGURE 14: CPC
FIGURE 15: THE CPC COMMUNICATES OVER THE
J1587 AND J1939 DATA LINKS TO THE VEHICLE
2.8 DDEC VI DIAGNOSTICS
2.8.1 Diagnostic system
Diagnostics is a standard feature of DDEC VI.
The purpose of this feature is to provide
information for problem identification and