CABLE 3792765 - Caterpillar

Electronic Controls
Electronic Control Module
The ECM supplies signals to the Electronic Unit Injectors. The ECM signals control the engine operation. The ECM consists of two main components, the control computer (hardware) and the Personality Module (software). The control computer consists of a microprocessor and electronic circuitry. The Personality Module is the software for the control computer which contains operating maps that define power and torque curves.The ECM governs engine speed. Desired engine speed is determined by the throttle position sensor signal and certain sensor readings. Diagnostic codes may derate the engine. Actual engine speed is determined by the Engine Speed/Timing signal.Fuel Injection
The ECM controls the timing of the fuel injectors. The ECM varies the signals to the fuel injectors. Fuel is injected ONLY while the fuel injector solenoid is energized by a 105 volt signal from the ECM. By controlling the timing and duration of the 105 volt signal, the ECM controls the fuel injection timing, the quantity of fuel and the desired engine speed.Injection timing depends on engine speed, load, and other operational factors. The ECM detects the top center of each cylinder. The ECM sends an injection signal at the desired time. The ECM limits engine power during cold mode operation. The ECM modifies the injection timing and the ECM cuts out the cylinders during Cold Mode operation. This will increase startability and this 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.The ECM is programmed at the factory which limits the quantity of fuel that can be injected. The Fuel Ratio Control (FRC) limits the amount of fuel in order to control exhaust smoke. The FRC is based on the maximum allowable ratio between fuel and air. The FRC Fuel Position is increased when the ECM senses a higher Turbocharger Compressor Outlet Pressure. This will allow more fuel into the cylinder.The Rated Fuel Position is a limit that is based on the engine power rating. This is similar to the rack stops and the torque spring on a mechanically governed engine. The Rated Fuel Position provides power. The Rated Fuel Position provides the power curves and the torque curves for a specific engine family.Engine Wiring Diagram
Illustration 1 g00810505
Typical schematicLocation Of The Engine Sensors
Illustration 2 g00800304
Typical left side view (1) Secondary ECM (2) Left turbocharger compressor inlet pressure sensor (3) Primary engine speed/timing sensor (4) Secondary engine speed/timing sensor (5) Electric starting motorLocation Of The Engine Sensors
Illustration 3 g00800305
Typical left side inset (6) Unfiltered fuel pressure sensor (7) Filtered fuel pressure sensor (8) Filtered engine oil pressure sensor (9) Unfiltered engine oil pressure sensor (10) Coolant temperature sensor (11) Primary ECM (12) Atmospheric pressure sensorLocation Of The Engine Sensors
Illustration 4 g00903202
Typical right side view (13) Right turbocharger compressor inlet pressure sensor (14) Air shutoff (15) Instrument panel (16) Alternator (17) Permanent timing calibration sensor (18) Air start solenoid (19) Air starting motor (20) Prelube oil