CAN Bus Diagnostics: How a $20 Multimeter Saves $800 in Shop Fees (and When You Need a Scope)

The voicemail came in at 6:47 PM on a Thursday. Fleet manager in Phoenix. 2018 Kenworth T680 dead in the bay—third time that month. A dozen U-codes littering the history, intermittent dash resets, a no-start that came and went like a desert thunderstorm. He’d already swapped an ECM on suspicion—a $2,500 paperweight now, sitting on his bench. […]