Troubleshooting

Electronic System
Overview
i05980308
System Overview
The engine is designed for electronic control of most
engine operating functions. The electronic system
consists of an Electronic Control Module (ECM), the
wiring harness, switches, sensors, and fuel injectors.
The engine ECM receives information from the
sensors and the switches on the engine. The engine
ECM processes the information that is collected in
order to control the engine. By altering the fuel
delivery with the fuel injectors, the engine ECM
controls the speed and the power that is produced by
the engine.
The following information provides a general
description of the control system. Refer to the
Systems Operation manual for detailed information
about the control system.
System Operation
Engine Governor
The ECM governs the engine. The ECM determines
the timing, the injection pressure, and the amount of
fuel that is delivered to each cylinder. These factors
are based on the actual conditions and on the
desired conditions at any given time during starting
and operation.
The ECM uses the throttle position sensor to
determine the desired engine speed. The ECM
compares the desired engine speed to the actual
engine speed. The actual engine speed is
determined through interpretation of the signals that
are received by the ECM from the engine speed/
timing sensors. If the desired engine speed is greater
than the actual engine speed, the ECM requests that
more fuel is injected in order to increase engine
speed.
Timing Considerations
Once the ECM has determined the amount of fuel
that is required, the ECM must determine the timing
of the fuel injection.
The ECM adjusts timing for optimum engine
performance and for the fuel economy. Actual timing
and desired timing cannot be viewed with the
electronic service tool. The ECM determines the
location of top center of the number one cylinder from
the signals that are provided by the engine speed/
timing sensors. The ECM determines when injection
should occur relative to the top center. The ECM then
provides the signal to the injector at the desired time.
Fuel Injection
The ECM sends a high voltage signal to the injector
solenoids in order to energize the solenoids. By
controlling the timing and the duration of the high
voltage signal, the ECM can control the following
aspects of injection:
• Injection timing
• Fuel delivery
Other ECM Functions for
Performance
Refer to Troubleshooting, “Configuration Parameters”
for supplemental information about the systems that
can be monitored by the ECM.
Programmable Parameters
Certain parameters that affect engine operation may
be changed with the electronic service tool. The
parameters are stored in the ECM. These
parameters are either system configuration
parameters or customer parameters.
System configuration parameters are set at the
factory. System configuration parameters affect
emissions or power ratings within an engine family.
Some of the parameters may affect engine operation
in an unusual way. An operator might not expect this
type of effect. Without adequate training, these
parameters may lead to power complaints or
performance complaints even though the engines
performance is to the specification.
Customer parameters are variable. Customer
parameters can be used to affect the characteristics
of the engine. Limits are set by the factory and by the
monitoring system.
UENR0612-07 9
Electronic System Overview
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