Using an oscilloscope on a vehicle's CAN bus, Technician A claims it can show message content while Technician B believes it can only monitor bus activity. Who is correct?

In this scenario, Technician B is correct because an oscilloscope can effectively monitor bus activity but does not typically show detailed message content on a Controller Area Network (CAN) bus. The primary function of an oscilloscope is to visualize electrical signals, making it capable of displaying waveforms and signal integrity. However, while it can indicate whether signals are present and provide information about the timing of the signals (i.e., showing data bits being sent over the bus), the oscilloscope does not decode or interpret the digital messaging content—this requires specialized tools such as a CAN bus analyzer or decoder.

Technician A's claim about the oscilloscope showing message content is misleading, as that would require a deeper level of protocol understanding and decoding capability that oscilloscopes lack. Thus, while both technicians have valid points about different aspects of what an oscilloscope can do, Technician B accurately recognizes the limitation regarding the decoding of message content.