This guide explains a demonstrated method for reading BMS data from Mercedes-Benz EQA/EQB/EQC modules using Xhorse Multi-Prog ECU Programmer. It covers wiring, chip selection, data reading, file saving, and the use of prepared pinouts for easier module connections.
Important Wiring Differences between the Chips
The BMS contains two chips with the same name, but their wiring diagrams are different. For this reason, it is important to identify the correct chip and follow the corresponding connection diagram.
The connection uses several color-coded wires:
- VCC
- GND
- Yellow reset wire
- Green wire
- Blue wires
- Purple wire
- Brown wire on the back of the module
Each wire must be connected to its corresponding position according to the correct wiring diagram.
Step 1: Connect the Module
First, connect the front-side wires according to their colors and positions.
The yellow wire is used for reset, while the remaining colored wires are connected to their matching points.
There is also an additional wire on the back of the module.
The brown wire must be connected to the specified position shown in the wiring diagram.
After completing all connections, connect the power supply.
Step 2: Select the Chip in Xhorse Multi Prog
After the hardware connections are complete, return to the computer and open Multi Prog software.
The chip model selected in the demonstration is:
SPC564B74
There are five files in total. The first file is read initially to identify and extract the data.
Step 3: Read the First File
To begin the reading process:
Select the SPC564B74 chip model.
Open the first file.
Start the identification process.
Wait for the software to complete the reading operation.
Check the resulting file after the read is successful.
Once the reading has finished, the extracted data will be displayed in the software.
Step 4: Save the Read Data
After confirming that the data has been read successfully, save the file properly.
Use the software’s Save function and store the data in the desired location. The demonstration emphasizes saving all extracted data carefully so it can be used later if necessary.
Step 5: Check the Wiring Diagram
The software also provides a wiring diagram for the chip. Normally, this type of connection must be made directly on the chip.
However, prepared pinouts are available for the modules, making the process easier than connecting directly to individual chip pins.
The prepared diagram shows the relevant connection positions, including:
- VCC
- TMS
- TCK
- TDI
Additional connections on the rear side of the module
The TCK connection is located on the back, while TDI and TMS are connected on the indicated side. Because the two chips have different diagrams, always use the diagram that corresponds to the chip being serviced.
Step 6: Read and Write Corrupted Data
BMS data can sometimes become corrupted. In those cases, the programmer can be used to read and write the data.
The demonstrated workflow is:
Connect the BMS according to the correct diagram.
Supply power to the module.
Select the appropriate chip model in Multi-Prog.
Read the available data.
Save the extracted files.
Use the programmer’s read/write functions to address corrupted data when required.
The transcript also notes that solutions are available for repairing corrupted data.
Conclusion
Repairing and reading the BMS for Mercedes-Benz EQAEQBEQC requires careful attention to the chip type and its specific wiring diagram. Using Xhorse Multi Prog Programmer, the data can be read, saved, and—when necessary—handled through read/write operations for corrupted data. The prepared module pinouts simplify the connection process, but every wire must be placed according to the correct diagram.
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