Steps, methods and precautions for fault diagnosis of CAN bus system

Infineon / Mitsubishi / Fuji / Semikron / Eupec / IXYS

Steps, methods and precautions for fault diagnosis of CAN bus system

Posted Date: 2024-02-04

Steps, methods and precautions for fault diagnosis of CAN bus system

CAN bus system fault diagnosis refers to the process of analyzing, locating and troubleshooting faults in the CAN bus system. This article will introduce the steps, methods and precautions for CAN bus system fault diagnosis in a detailed, detailed and detailed manner.

1. Troubleshooting steps

1. Confirm the fault phenomenon: First, it is necessary to confirm the fault phenomenon of the CAN bus system. For example, check whether the system cannot communicate normally, whether there are data errors, etc.

2. Collect information: Collect system-related information, including fault codes, alarm information, time and location of fault occurrence, etc. You can also obtain more fault information by using fault diagnosis tools (such as fault code scanning tools).

3. Analyze the cause of the failure: Analyze the cause of the failure based on the collected information. Possible causes of failure include electrical failure, communication failure, software failure, etc. When analyzing, you can refer to the working principle and related technical information of the CAN bus system.

4. Fault location: Determine the specific location where the fault occurs. Fault location can be performed through the following methods:

- Check the physical connection: Check whether the cable connection of the CAN bus interface is loose, damaged or has poor contact.

- Test node voltage: Use a digital multimeter or oscilloscope to check whether the voltage of the node is normal.

- Check communication quality: Use a CAN bus analyzer or oscilloscope to detect the sending and receiving of data packets to determine whether the communication quality is good.

5. Troubleshooting: According to the fault location results, take corresponding measures to troubleshoot. Possible troubleshooting methods include:

- Repair physical connections: Reconnect, replace or repair damaged cables, connectors, etc.

- Fix power issues: Check the power lines to determine if the power supply is normal.

- Reset the system: Try to restart the CAN bus system to resolve possible software failures.

6. Testing and verification: After troubleshooting, perform testing and verification to ensure that the fault has been resolved. You can check whether there are other problems by repeating the previous fault symptom test or using a fault code scanning tool.

7. Recording and analysis: Record the process and results of fault diagnosis and conduct analysis. This helps understand the system's failure modes and frequencies, making future troubleshooting more efficient.

2. Fault diagnosis method

1. Use a fault code scanning tool: The fault code scanning tool is a portable device that can be connected to the CAN bus system and read out the system's fault codes and alarm information. With this information, the cause and location of the fault can be diagnosed more accurately.

2. Physical inspection and measurement: Check the physical connections of the CAN bus system, including cables, connectors, etc. Use instruments such as digital multimeters or oscilloscopes to detect the voltage, current, waveform and other parameters of the nodes to determine the working status of the hardware components.

3. Communication quality analysis: Use a CAN bus analyzer or oscilloscope to monitor and analyze the data packets on the bus. By analyzing the sending and receiving of data packets, you can determine whether the communication quality is normal and whether there are problems such as bit errors and interference.

4. Software diagnosis: Diagnose the software of the CAN bus system, including checking software version, setting parameters, debugging programs, etc. Diagnostic software tools can be used to detect and interpret CAN bus system data.


1. Ensure safety: When performing fault diagnosis, pay attention to protecting your own safety. Avoid touching high-voltage parts, hot parts or rotating parts, and be careful to avoid risks such as electric shock and burns.

2. Detailed records: During the fault diagnosis process, the operations and results of each step must be recorded in detail. This facilitates review and analysis and improves the accuracy of fault location.

3. Use the correct tools and instruments: Select appropriate tools and instruments for fault diagnosis as needed. For example, use digital multimeters, oscilloscopes, CAN bus analyzers, etc. for measurement and analysis.

4. Familiar with technical information: Before performing fault diagnosis, you must be familiar with the technical information of the CAN bus system, including hardware and software related documents. This can help to better understand the workings and failure modes of the system.

5. Combining practical experience: In addition to using fault diagnosis tools and instruments, it is also necessary to combine practical experience for fault diagnosis. Quickly locate and eliminate faults based on past fault cases and solutions.


The steps of CAN bus system fault diagnosis mainly include confirming the fault phenomenon, collecting information, analyzing the cause of the fault, fault location, troubleshooting, testing and verification, recording and analysis. Fault diagnosis methods mainly include using fault code scanning tools, physical inspection and measurement, communication quality analysis, software diagnosis, etc.

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