Medium and Heavy Trucks
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Hi my name is***** will be glad to help. J1939 is the datalink harness that the ECM uses for communication. Inspect the ECM harness and connector pins for damage or corrosion and check the ECM power and grounds for loose connections. Check the ECM power wiring between the battery box and ECM as well for loose connections. there should be more numbers for your fault code. J1939 is a description and not the actual fault. Let me know the full code number or the flash codes you have in the ECM memory.
Here is a diagram that will help Identify your connector pins and wiring.