What are the characteristics of faults that may occur in the CAN bus system? Chengdu Panfeng Technology

What are the characteristics of bus system failures? Chengdu Panfeng Technology
Today, let’s take a look at the common phenomena of bus system failures. When a car network system fails, there are usually some obvious symptoms. feature. However, the fault phenomena are often rather strange. For example, the fault phenomenon is similar to the superposition of multiple single faults, the voltages of multiple electronic control units are abnormal, and the control units in the data bus LAN cannot communicate with each other through the bus, making the vehicle multiple This kind of functional abnormality sometimes even causes the fault reader to be unable to communicate with the system and perform fault diagnosis.
Dupanfeng Technology Engineer introduced that when a car network system fails, the common failure phenomena can be summarized into the following aspects.
The entire system is paralyzed
The entire bus control system is paralyzed, or multiple electronic control units in the system work abnormally or cannot enter normal working status.
Multiple different fault phenomena occur at the same time
Multiple different fault phenomena occur at the same time in different systems and different parts, and there is often no direct connection between these fault phenomena.
Unable to perform data communication with the fault diagnosis instrument
After an electronic control unit or multiple electronic control units are connected to a dedicated fault diagnosis instrument, data communication with the fault diagnosis instrument cannot be performed.
What are the types and characteristics of line system faults? Let’s follow the editor of Chengdu Panfeng Technology to learn about it
Common types of vehicle network system failures mainly include vehicle power supply system failures, vehicle network transmission system link failures, and vehicle network transmission system link contact failures.
Vehicle power supply system failure
The control core part of the automobile on-board network system is the electronic control module assembly containing the interface communication integrated circuit chip. This type of control module is usually referred to as "." on the circuit. The operating voltage is generally between.
If the normal working voltage provided by the vehicle power system is lower than . , some electronic control module components that are sensitive to the power supply voltage or have higher requirements will be unstable or unable to work, which will cause The communication of the car's in-vehicle network system is unstable or cannot communicate. This will inevitably cause the vehicle to fail to work or work abnormally.
In-vehicle network transmission system link failure
In-vehicle network transmission system link failure is also called communication line failure. Common failures are short circuit, open circuit or changes in the physical characteristics of the line that cause communication Signal interruption, distortion, attenuation, etc. will cause multiple control systems in the vehicle network transmission system to fail to work or the electronic control system to act incorrectly.
When troubleshooting vehicle network transmission system link failures, it is more intuitive to use an oscilloscope or a special automotive fiber optic repair instrument to observe the communication data signal, and compare the detected data signal waveform with the data signal waveform during normal communication. By comparison, the cause of the failure can usually be determined quickly.
In addition, for system instability caused by link failures in the vehicle network transmission system, during maintenance, a fault diagnosis instrument can be used to read bus fault codes to determine the cause of the failure.