J1939 Communication Faults Explained: Wiring, Termination and Module Checks
Multiple truck warning lights can come from one communication problem. Learn what J1939 faults mean, how termination works, and why module power checks matter.
Detroit Diesel
SPN and FMI Codes Explained: Why a Fault Code Doesn’t Identify a Bad Part
A diesel truck fault code identifies a detected condition, but it may not identify the failed part. Learn how to read SPN and FMI codes and approach diagnosis.