Today, I’d like to explain the differences between the ECU systems of SDLG and Volvo.
Many people used to think that SDLG and Volvo’s systems are identical. It’s true that the two companies had a close and successful cooperation for a period before 2021, and their products rolled off the same production line. This led to the common misconception that the two systems are more or less the same. However, that is not the case.
Around 2021, SDLG embarked on independent R&D and started developing its own supporting products. This included the main ECU of its electronic control system, which was independently designed and developed by SDLG and is known in the industry as the Beigu Electronic Control System.
Let’s take a brief look at the main board of the Beigu system. It retains some features of the Volvo system. For example, its interface is identical to Volvo’s, but the relevant definitions have been modified. Additionally, it has eliminated the function of one 1587 communication line found in the Volvo system, retaining only the CAN bus function.
This is why many customers and excavator operators report that they cannot view engine voltage data or engine alarm information on-site—it is a direct result of SDLG removing the 1587 fault alarm line. This has also left many repair technicians confused and struggling to troubleshoot faults, which is an inherent drawback of this modification.
Therefore, a reminder for repair work: always first identify the SDLG model and the type of system it uses. Models manufactured before 2021 are likely equipped with the Volvo system. For models made after 2021, or even some produced after 2018 or 2019, a portion may already use the Beigu system. You can distinguish them by looking at the outer casing—there are significant differences between the Volvo and Beigu ECUs. Different systems require different troubleshooting methods.
Let’s take an example: suppose a 400 Plus model has an issue where the proportional valve has no output. The testing method for this differs from that of Kawasaki proportional valves. With the Beigu system, you can disconnect the proportional valve component and test it directly. Under normal conditions for this model, you should be able to measure a 24V voltage at the interface. Once the proportional valve is connected, the voltage will drop to within 10V. If there is a fault, the voltage measured at the interface will not be 24V—it may be around a dozen volts. This is exactly what you would detect in an open-circuit test.
There are also other common faults. For instance, if the hour meter reading of a 600 model suddenly resets to 0, or jumps to one hundred thousand or several hundred thousand hours, the problem is most likely with the control unit.
Other issues like inability to rev up the engine or failure to start normally may also be caused by ECU malfunctions. In such cases, the ECU needs to be removed for testing.
These are some common faults associated with the Beigu system. I hope this information is helpful to friends in the industry.
