
RENR9348-01 5
Troubleshooting Section
Troubleshooting Section
Electronic Troubleshooting
i02436970
System Overview
SMCS Code: 19
00
System Opera
tion
This engine is electronically controlled. Each cylinder
has an electr
onic unit injector. The Electronic Control
Module (ECM) sends a signal to each injector
solenoid in order to control the operation of the fuel
injection sy
stem.
Electronic Controls
The electronic system consists of the following
components: the ECM, the Electronic Unit Injectors
(EUI), the w
iring harness, the switches, and the
sensors. The ECM is a computer that is used to
control the engine. The software for the computer
is loaded v
ia the flash file. The flash file contains
the operating maps and the performance maps
for the engine. These maps define the following
character
istics of the engine:
•
Horsepower
•
Torque curves
The ECM ca
lculates the timing and the amount of fuel
that is delivered to the cylinders. These calculations
are based on the actual conditions and/or on the
desired c
onditions at any given time.
The ECM compares the desired engine speed to
the actua
l engine speed. The ECM calculates actual
engine speed from signals that are produced by the
engine speed/timing sensor. The desired engine
speed is
calculated by the ECM with the following
variables:
•
Throttl
e signal
•
Input signals from engine sensors
•
Certain diagnostic codes
If the de
sired engine s peed is greater than the actual
engine speed, the ECM increases the duration of the
fuel injection. This injects more fuel into the cylinders
in order
to increase the actual engine speed.
Cold Mode
The ECM limits engine power during cold mode
operation. Injection timing is also modified during
cold mode oper
ation. Cold mode operation provides
the following benefits:
•
Increased col
d weather starting capability
•
Reduced warm-up time
•
Reduced white smoke
Cold mode is ac
tivated whenever the engine
temperature falls below a predetermined value. Cold
mode remains active until the engine temperature
rises above a
predetermined value or until a time
limit is exceeded.
Fuel Injecti
on
The ECM controls the amount of fuel that is injected
by varying th
e duration of the signals to the injectors.
The injector will pump fuel only while the injector
solenoid is energized. The ECM sends a high voltage
signal to th
e solenoid. This high voltage signal
energizes the solenoid. By controlling the timing and
the duration of the high voltage signal, the ECM can
control inj
ection timing and the engine RPM.
The flash file that is programmed into the ECM
sets certa
in limits on the amount of fuel that can
be injected. The “FRC Fuel Limit” is used to control
the air/fuel ratio in order to control emissions. The
“FRC Fuel L
imit” is a limit that is based on the boost
pressure of the engine. A higher boost pressure
indicates that there is more air in the cylinder. As
the boost
pressure increases, the ECM calculates
an increased “FRC Fuel Limit”. When the “FRC Fuel
Limit” is increased, the ECM injects more fuel into the
cylinder
. The “FRC Fuel Limit” is programmed into
the ECM at the factory. This fuel setting cannot be
changed by the customer.
The “ Rated Fuel Limit” is a limit that is based on the
power rating of the engine and on engine rpm. The
“Rated F
uel Limit” is a fuel map that provides the
power curves and the torque curves for a specific
engine family and for a specific engine rating. The
“Rated
Fuel Limit” is programmed into the ECM at
the factory. This fuel setting cannot be changed by
the customer.