Service Technicians vs. Auto Mechanics

a cool trick I learned is to use a graphing multimeter for me or can I pick and roll if you don't see a fast and rapid square sine wave there is a problem if does signal is flat or has spikes is a job primary voltage to a secondary voltage would indicate on an oscilloscope for example that would be an indication of noise on your can or data line using this method has helped me find faulty individual issues in the past . a flatline usually indicates a shorted or dead can bus