The vehicle control unit (DDEC-VCU) communicates between the DDEC-ECU and other electronic control units installed on the vehicle over the J1587 datalink. See Figure 43384 . Within the DDEC-VCU, sets of data for specific applications are stored. These include idle speed, maximum running speed, and speed limitation.
Vehicle Control Unit (DDEC-VCU)
The DDEC-VCU receives data from the following sources:
From this 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. If the engine control system detects a fault, the appropriate fault code is broadcast on the datalink and can be read using minidiag2. When there is a fault, the code for the control unit reporting the fault can be read directly on the ICU display.