Case Fault Code

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U1001

Dash is "Dark."

System

Electrical (CAN)

Symptom

Dash is "Dark."

Diagnosis & fix steps

LOGIC: CAN Communication timeout between the Monitor and Engine ECM. ACTION: Check the J1939 backbone resistance (should be 60 Ohms with power off).

Red Seal field insights

Pro-Tip: Check the Bulkhead Connector behind the cab. It's the #1 spot for vibration-induced pin wear. A tiny wiggle here kills the whole data link.

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