ROD AS 7Y4914 - Caterpillar

The engine is designed for electronic control of most engine operating functions. The electronic system consists of the following components: Electronic Control Module (ECM), wiring harness, switches, sensors and fuel injectors. The engine ECM receives information from the sensors and from the switches on the engine. The engine ECM processes the information that is collected in order to decide on the control of the engine. By altering the fuel delivery to the fuel injectors, the engine ECM controls the speed and the power that is produced by the engine.Electronic Controls
Electronic Control Module
The ECM consists of two main components, the control computer (hardware) and the flash file. The control computer consists of a microprocessor and of electronic circuitry. The flash file contains the engines operational characteristics. The operating maps influence the engines performance.Engine Governor
The engine ECM governs engine speed. The engine ECM and the flash file work together by controlling the amount of fuel that is delivered by the injectors. Desired engine rpm is determined by the throttle position sensor signal and by certain sensor readings. Diagnostic codes may derate the engine. Actual engine rpm is measured by the engine speed/timing sensor.Fuel Injection
The engine ECM controls the timing, the duration, and the pressure of the fuel that is injected. The engine ECM varies the signals to the fuel injectors. Fuel is injected only while an injector solenoid is energized by a 105 V signal from the engine ECM. The timing of the injection signal determines the engine timing. The length of the injection signal determines engine speed. By controlling the timing and duration of the 105 V signal, the ECM controls the engine speed.Cold Mode Operation
The engine ECM uses cold mode operation in order to reduce white smoke during engine warm-up. The engine ECM cuts out the injectors one at a time in order to determine if the cylinder is firing. If the cylinder is firing correctly, the engine ECM leaves the injector on. If the cylinder is not firing, the engine ECM will leave the injector turned off. This action will increase startability and this action will reduce warm-up time.Cold mode is activated whenever the engine coolant temperature falls below a predetermined value. Cold mode remains active until the engine has warmed or a time limit is exceeded.Rated Fuel Position
The rated fuel position is a limit that is based on the power rating of the engine. The rated fuel position is similar to the rack stops and the torque spring on a mechanically governed engine. The rated fuel position determines maximum power and torque values for a specific engine family and for a specific rating. The rated fuel position is programmed into the flash file.Block Diagram of Electronic Governor
Illustration 1 g00928043
Typical exampleEngine Wiring Diagram
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Typical exampleLocation Of The Engine Sensors
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Left side view (1) Exhaust temperature sensor (LH) (2) Engine speed/timing sensor (3) Engine ECM (4) ECM connector J2/P2 (5) ECM connector J1/P1 (6) Atmospheric pressure sensor (7) Unfiltered engine oil pressure sensor (8) Low oil level sensor (9)