MBE 900 OPERATOR'S GUIDE These data are evaluated together with the data from the sensors on the engine, such as coolant and fuel temperature and oil and charge pressure. The data is then compared to the characteristic maps or lines stored in the DDEC-ECU. From these data, quantity and timing of injection are calculated and the unit pumps are actuated accordingly through the solenoid valves. Figure 18 DDEC-VCU NOTE: To obtain a replacement DDEC-ECU, all the data given on the DDEC-ECU label are required. The DDEC-VCU receives data from the following sources:
The operator (accelerator pedal position, engine brake switch) The DDEC-ECU data label has the 10 digit engine serial number (see Figure 14), the engine horse power and torque. Other electronic control units (for example, the anti-lock brake system) The DDEC—ECU (oil pressure and coolant temperature) DDEC-VCU The DDEC-VCU communicates with any other electronic control unit installed on the vehicle over the J1587 data link. See Figure 18. From these data, instructions are computed for controlling the engine and transmitted to the DDEC-ECU via the proprietary datalink.
The DDEC-VCU controls various systems, for example, communications with the datalink, the engine brake, and the constant-throttle valves. Data for specific applications is stored in the DDEC-VCU. These include idle speed, maximum running speed, and speed limitation. All information subject to change without notice. (Rev. 04/08) 27 DDC-SVC-MAN-0055 04/08 Copyright © 2008 DETROIT DIESEL CORPORATION