In this paper, a study was conducted on the analysis of communication circuit faults using oscilloscope waveform analysis. Circuit resistance was calculated based on voltage and operating current values using a simple equation, and it was confirmed that the increase in resistance of the communication circuit could be analyzed by analyzing the voltage level during transmitter operation. By combining information of the controller ID, the location of the fault was identified and it was concluded that the location of the fault can be quickly found by analyzing the oscilloscope waveform and the controller ID information. Additionally, the value of communication line contact resistance can be calculated using a simple equation, and the location of the fault can be found by analyzing the communication voltage level and ID information.

In this study, when a communication wire harness is defective due to long-term operation of a vehicle with a high-speed CAN communication network, the unique ID information of each controller and the oscilloscope waveform are analyzed to find defects. As a result of the experiment, it was possible to know whether the circuit of the main wiring was disconnected by the differential voltage analysis, and it was possible to confirm whether the sub-wiring was disconnected due to the generation of saw blade waveforms in the bus idle part. In addition, the fault location could be found with controller ID information and communication circuit analysis.

In the event of an defective wire in the low-speed CAN communication of vehicle, the problem had to be solved by relying on fault codes or using expensive measuring equipment. An experiment was conducted to analyze waveforms of communication circuits with wire conditions such as normal, short circuits in the main body, and mutual short circuits. When the controller drives the CAN transceiver and transmits a message, the voltage and current waveforms were measured using an OEM oscilloscope to check for abnormalities in the circuit. As a result, it was confirmed that when a defective wire occurs in low-speed CAN communication, the CAN driver can switch to the fail-safe mode to exchange normal messages.

In order to identify the CAN message sent from the ECU, the CAN waveform and operating current were measured during the operation of the CAN driver.CAN ID was identified in the same phase as the measured voltage waveform and operating current, and reverse engineering was performed .And, by measuring CAN bus wire EMI noise, it was tested whether CAN ID was identified.CAN ID verified ECU data using CAN analyzer.

In this paper, each controller's unique ID and PICO oscilloscope were used to measure the voltage waveform of each CAN communication line, and compare and analyze the serial decoding results. Using the voltage change level of the CAN communication line, it was possible to check whether the CAN-High line and the Low line were disconnected. And it was possible to infer the circuit disconnection point between the controller and the controller only with the unique ID information of each controller. And when the CAN-High circuit was disconnected, the voltage of the high line was measured at the same voltage level as the Low line.