PLATE AS LH 3C8705 - Caterpillar

Illustration 1 g01205842
Top view
(1) Intake manifold air temperature sensor
(2) Intake manifold pressure sensor
(3) Coolant temperature sensor
(4) Atmospheric pressure sensor
(5) Secondary engine speed/timing sensor
(6) Coolant level sensor
(7) Oil pressure sensor
(8) Electronic Control Module (ECM)
Illustration 2 g01387178
Front view
(9) Primary engine speed/timing sensor
Illustration 3 g01387177
Section A-A
(10) Fuel pressure sensor
(11) Fuel temperature sensor The electronic control system is integrally designed into the engine's fuel system and the engine's air inlet and exhaust system in order to electronically control the fuel delivery. The electronic control system provides better timing control and fuel air ratio control in comparison to conventional mechanical engines. Injection timing is achieved by the precise control of the fuel injectors. Engine speed is controlled by adjusting the injection duration. The Electronic Control Module (ECM) energizes the unit injector solenoids in order to start the injection of fuel. Also, the ECM de-energizes the unit injector solenoids in order to stop the injection of fuel. Refer to Systems Operation/Testing And Adjusting, "Fuel System" for a complete explanation of the fuel injection process.The engine uses the following three types of electronic components:
Input component
Control component
Output componentAn input component is one that sends an electrical signal to the ECM. The signal that is sent varies in either of the following ways:
Voltage
Frequency
Pulse widthThe variation of the signal is in response to a change in some specific system of the engine. Some specific examples of an input component are the engine speed-timing sensors, and the coolant temperature sensor. The ECM interprets the signal from the input component as information about the condition, environment, or operation of the engine.An ECM receives the input signals from the input components. Electronic circuits inside the control component evaluate the signals from the input components. These electronic circuits also supply electrical energy to the output components of the system. The electrical energy that is supplied to the output components is based on predetermined combinations of input signal values.An output component is one that is operated by a control module. The output component receives electrical energy from the control group. The output component uses electrical energy to make an adjustment in one of the engine's systems. An output component may also provide information to the operator.As an example, a moving solenoid plunger will perform work. By performing work, the component has functioned in order to regulate the engine.As an example, a control panel light or an alarm will provide information to the operator of the engine.These electronic components provide the ability to electronically control the engine operation. Engines with electronic controls offer the following advantages:
Improvement in performance
Improvement in fuel consumption
Reduction in emissions levelsVarious sensors feed data to the ECM. The following sensors are used by the ECM for data:
Engine coolant temperature
Engine oil pressure
Atmospheric pressure
Primary speed/timing sensor
Secondary speed/timing sensor
Intake manifold air pressure
Intake manifold air temperatureThe ECM processes the data. Then, the ECM sends an electronic signal to the fuel injector. The signal will control the amount of fuel that is injected into the cylinder. This will optimize the efficiency and the performance of the engine.Data Link
A data