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 rpm is determined by the throttle position sensor signal and certain sensor readings. Diagnostic codes may derate the engine. Actual engine rpm is determined by the Engine Speed/Timing signal.
Fuel Injection
The ECM controls the timing of the injectors. The ECM varies the signals to the injectors. 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 rpm.
Injection timing depends on engine rpm, 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. 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 FRC Fuel Position controls the fuel limit for exhaust smoke. The FRC Fuel Position is based on the maximum allowable air/fuel ratio. 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 for the 3508B Engine with CMS and Without 2301A Loadshare
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| Illustration 1 | g00776463 |
Engine Wiring Diagram for the 3508B Engine with EMCP II and 2301A Loadshare
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| Illustration 2 | g00638235 |
Location Of The Engine Sensors
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| Illustration 3 | g00737300 |
Left Side View (1) Coolant temperature sensor. (2) Left exhaust temperature sensor. (3) Primary engine speed/timing sensor. (4) Crankcase pressure sensor. (5) Aftercooler temperature sensor. | |
Location Of The Engine Sensors
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| Illustration 4 | g00737719 |
Right Side View (6) Right exhaust temperature sensor. (7) Filtered fuel pressure sensor. (8) Unfiltered fuel pressure sensor. (9) Filtered engine oil pressure sensor. | |
Location Of The Engine Sensors
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| Illustration 5 | g00737721 |
Rear View (10) Left turbocharger compressor inlet pressure sensor. (11) Right turbocharger compressor inlet pressure sensor. | |
Location Of The Engine Sensors
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| Illustration 6 | g00737720 |
Front View (12) Unfiltered engine oil pressure sensor. (13) Turbocharger compressor outlet pressure sensor. (14) Atmospheric pressure sensor. (15) Electronic control module. | |