2 OPERATION Section Page 2.1 DDEC BENEFITS .................................................................................... 2-3 2.2 FEATURES .............................................................................................. 2-4 2.3 DDEC SYSTEM--HOW IT WORKS ......................................................... 2-5 2.4 DDEC RELATED PUBLICATIONS ........................................................... 2-23
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1-SECM-03-02.PDF - OPERATION - DDCSN - Detroit Diesel ... · PDF fileThe major components of the DDEC system consist of the electronic control module (ECM), ... 1-SECM-03-02.PDF -
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All Detroit Diesel On-Highway engines come standard with Detroit Diesel Electronic Controls(DDEC®). The state of the art Electronic Control Module (ECM) allows precise control of theengine management system that provides:
Excellent engine performanceOptimum fuel economyEmissions to meet current laws without after treatmentEngine diagnosticsSimple programming
All information subject to change without notice. (Rev. 2/03)
The major components of the DDEC system consist of the electronic control module (ECM),the electronic unit injectors (EUI) and the various system sensors. The purpose of the sensors isto provide information to the ECM regarding various engine performance characteristics. Theinformation sent to the ECM is used to instantaneously regulate engine and vehicle performance.
2.3.1 Electronic Unit Injector
An electronic unit injector incorporates a solenoid operated poppet valve which performs theinjection timing and metering functions. When the solenoid valve is closed, pressurization andfuel injection is initiated. Opening the solenoid valve releases injection pressure, ending injection.The duration of valve closure determines the quantity of fuel injected. See Figure 2-1.
Figure 2-1 Electronic Unit Injector
2.3.2 Electrical Connectors
Provide water-tight connections for the harnesses between the sensors and the ECM.
All information subject to change without notice. (Rev. 2/03)
The air temperature sensor is located in the air intake manifold and monitors the air temperatureentering the engine. The ECM adjusts the engine timing to reduce white smoke, improve coldstarts, and provide engine protection. See Figure 2-2. For EGR sensor, see Figure 2-3.
Figure 2-2 Air Temperature Sensor
Figure 2-3 Air Temperature Sensor With EGR
(Rev. 2/03) All information subject to change without notice.
The CTS is located on the right side of the engine. The engine protection feature will be triggeredif the coolant temperature exceeds the specified limits. See Figure 2-4. See Figure 2-5 for sensorwith EGR.
Figure 2-4 Coolant Temperature Sensor
Figure 2-5 Coolant Temperature Sensor With EGR
All information subject to change without notice. (Rev. 2/03)
The fire truck pump pressure sensor is used to monitor water pressure for the Pressure GovernorSystem in the DDEC system. The signal back to the ECM changes r/min which allows the firetruck water pump to maintain a steady water pressure during pumping operation in fire trucks.See Figure 2-6.
Figure 2-6 Fire Truck Pump Pressure Sensor
(Rev. 2/03) All information subject to change without notice.
2.3.6 The Synchronous Reference Sensor (SRS) and Timing ReferenceSensor (TRS)
These sensors control the timing of the engine. The SRS sensor provides a "once per camrevolution" signal and the TRS sensor provides a "36 per crankshaft revolution" signal. Workingtogether, these sensors tell the ECM which cylinder is at top-dead-center for cylinder firing.Precise monitoring of piston position allows for optimum injection timing, resulting in excellentfuel economy and performance with low emissions. See Figure 2-7 for the SRS and the TRS.
Figure 2-7 Timing Reference Sensor and Synchronous Reference Sensor
All information subject to change without notice. (Rev. 2/03)
The oil temperature sensor optimizes idle speed and injection timing to improve cold startingability and reduce white smoke. This sensor will activate the engine protection system if the oiltemperature is higher than normal.
The fuel temperature sensor provides a signal to the ECM. The ECM utilizes the fuel temperaturesignal to adjust the fueling for changes in the fuel density as a function of temperature to maintainhorsepower. See Figure 2-8. For sensors with EGR, see Figure 2-9.
Figure 2-8 Oil and Fuel Temperature Sensors
Figure 2-9 Oil and Fuel Temperature Sensors With EGR
(Rev. 2/03) All information subject to change without notice.
The ECM is the brain of the computer system, receiving electronic inputs from the operator aswell as from the engine and vehicle mounted sensors. See Figure 2-10.
Figure 2-10 Electronic Control Module
All information subject to change without notice. (Rev. 2/03)
The electronic foot pedal assembly instantaneously converts the operator’s throttle input into asignal to the ECM. The throttle response is fast and accurate. The TPS is self-calibrated, andrequires no maintenance. See Figure 2-12.
Figure 2-12 Throttle Position Sensor
All information subject to change without notice. (Rev. 2/03)
In monitoring turbocharger compressor discharge, the TBS provides air pressure data to theECM for smoke control during engine acceleration. See Figure 2-14. For sensor with EGR,see Figure 2-15.
Figure 2-14 Turbocharger Boost Sensor
Figure 2-15 Turbocharger Boost Sensor With EGR
All information subject to change without notice. (Rev. 2/03)
The OPS will activate the engine protection system when the oil pressure falls below a normal oilpressure at a given engine r/min. See Figure 2-16. For sensor with EGR, see Figure 2-17.
Figure 2-16 Oil Pressure Sensor
Figure 2-17 Oil Pressure Sensor With EGR
(Rev. 2/03) All information subject to change without notice.
The FPS monitors fuel pressure to warn the operator of impending power loss. This feature isoptional. It is not used in international applications. See Figure 2-18.
Figure 2-18 Fuel Pressure Sensor
2.3.15 Turbo Compressor Outlet (TCO) Temperature Sensor
The TCO sensor is located in the outlet of the turbocharger, compressor side, and measurestemperature. If the temperature gets too high, the ECM can derate the power. See Figure 2-19.
Figure 2-19 Turbo Compressor Outlet Temperature Sensor
All information subject to change without notice. (Rev. 2/03)
This sensor is located in the engine harness, tie-wrapped on the right side under the manifold.See Figure 2-24.
Figure 2-24 Barometric Pressure Sensor
2.3.21 EGR Delta Pressure Sensor (DPS)
The EGR Delta-P sensor measures the difference in pressure across the venturi in the cold pipe. Itis used with the EGR temperature sensor to determine exhaust gas flow. See Figure 2-25.
Figure 2-25 EGR Delta Pressure Sensor
All information subject to change without notice. (Rev. 2/03)
The EGR temperature sensor is located in the cold side EGR piping and monitors temperature.This sensor and the Delta-P sensor data are used to calculate the exhaust gas flow. See Figure 2-26.
Figure 2-26 EGR Temperature Sensor
2.3.23 Oil Level Sensor (OLS)
The OLS is part of the Maintenance Alert System (MAS) and monitors the oil level.See Figure 2-27.
Figure 2-27 Oil Level Sensor
(Rev. 2/03) All information subject to change without notice.