How to Diagnose J1939 ground offset Issues: The Silent Network Killer That Multimeters Miss

Author Note: I’m writing this because last month I watched a fleet operator replace four engine ECUs in two weeks. Every one of them failed the same way. The multimeter said the ground was fine. It wasn’t. This article is what I wish someone had handed me fifteen years ago. If you work with J1939 long enough, you […]