HUB AS 1171732 - Caterpillar

Electronic Controls
Electronic Control Module
The ECM consists of two main components, the control computer (hardware) and the flash file (software). The ECM consists of a microprocessor and electronic circuitry. The flash file is the software for the control computer which contains operating maps that define power and torque curves. The ECM monitors the engine parameters during operation. The ECM supplies signals to the injector solenoids.The ECM governs engine speed. Desired engine speed is determined by the throttle signal and by certain sensor readings. Actual engine speed is supplied to the ECM by the engine speed/timing sensor.Fuel Injection
The ECM controls the timing of the engine by varying the signals to the electronic solenoids that control fuel injection. Fuel is injected only while an 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 desired engine speed, load, and other operational factors.The ECM limits engine power during cold mode operation. The ECM may modify the injection timing and the ECM may cut out certain engine cylinders in 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 coolant temperature has risen above a set temperature. The ECM is programmed at the factory to limit the quantity of fuel that can be injected. The position of the Fuel Ratio Control (FRC) controls the fuel limit for exhaust smoke. The FRC is based on the maximum allowable ratio of fuel to 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 limits the power curve and the torque curve for a specific engine family.Illustration 1 is a block diagram of the engine's electrical system.
Illustration 1 g01239935
Block diagram of engine components
Location of the Engine Components
Illustration 2 g01312507
Left side view
(1) Aftercooler temperature sensor
(2) Engine coolant temperature sensor
(3) Engine speed/timing sensor
(4) Left exhaust temperature sensor Location of the Engine Components
Illustration 3 g01312508
Right side view
(5) Right exhaust temperature sensor
(6) Timing calibration sensor
(7) Crankcase pressure sensor Location of the Engine Components
Illustration 4 g01312509
Front and back view
(2) Coolant temperature sensor
(1) Aftercooler temperature sensor
(8) Turbocharger compressor outlet pressure sensor
(9) Atmospheric pressure sensor
(10) Left turbocharger compressor inlet pressure sensor
(4) Left exhaust temperature sensor
(5) Right exhaust temperature sensor
(11) Right turbocharger compressor inlet pressure sensor
(12) ECM connector J1
(13) ECM
(14) ECM connector J2 Location of the Engine Components
Illustration 5 g01241242
Right front
(15) Filtered engine oil pressure sensor
(16) Unfiltered fuel pressure sensor
(17) Filtered fuel pressure sensor
(18) Unfiltered engine oil pressure sensor