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Home >> Dodge and Ram >> 2009 >> Durango Base, 3.7 K >> Repair and Diagnosis >> Transmission >> Transmission Control Systems >> Final Drive Control Module (FDCM) - Electrical Diagnostics >> DTC Troubleshooting >> U0121-Lost Communication With Abs >> Theory Of Operation
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Theory Of Operation

The Anti-Lock Brake System (ABS) Module communicates with other controllers over the CAN C bus. The Final Drive Control Module (FDCM) continuously monitors the bus activity and receives the messages it needs. If the FDCM does not receive messages from the ABS Module , then this fault will set and the service 4WD is illuminated.