Case IH 520330-14 - BCM – BCM: Communication network failure on CAN Bus B (short circuit)

A communication network failure on CAN Bus B, specifically a short circuit between the CAN_L (Low) and CAN_H (High) lines (or a short to ground). This causes the differential voltage required for data transmission to be lost, corrupting data packets and preventing communication across that specific bus segment.

• MAGNUM AFS Connect
• Case IH Magnum AFS Connect 180
• Case IH Magnum AFS Connect 200
• Case IH Magnum AFS Connect 220
• Case IH Magnum AFS Connect 240
• Case IH Magnum AFS Connect 250
• Case IH Magnum AFS Connect 280
• Case IH Magnum AFS Connect 310
• Case IH Magnum AFS Connect 340
• Case IH Magnum AFS Connect 380
• Case IH Magnum AFS Connect 400
• Case IH Steiger AFS Connect 540
• Case IH Steiger AFS Connect 550
• Case IH Steiger AFS Connect 580
• Case IH Steiger AFS Connect 600
• Case IH Steiger AFS Connect 620

1. 1

   Verify battery voltage is stable (12.4–14.6 V) and battery connections are clean and tight.

2. 2

   With the battery disconnected, measure the resistance between the CAN_L and CAN_H pins for CAN Bus B at the diagnostic port or BCM connector (should be approximately 60 ohms; near 0 ohms confirms a hard short).

3. 3

   Isolate the short by disconnecting modules on CAN Bus B one at a time and re-checking resistance. If resistance returns to normal, the last disconnected module is shorted. If all are disconnected and the short remains, the harness is shorted.

4. 4

   Physically inspect the CAN Bus B wiring harness for pinch points, chafing against the chassis, melted insulation, or water ingress/corrosion at the BCM connector pins.

1. 1

   Harness Repair

   If the short is found in the wiring harness, carefully cut out the damaged section. Splice in new twisted-pair CAN wire. You must maintain the wire twist as close to the splice as possible to prevent electromagnetic interference. Seal the repair with marine-grade heat shrink.

2. 2

   Module Replacement

   If the short is isolated internally to the BCM, remove the mounting hardware and harness connectors, and install a new BCM.

3. 3

   Reassembly

   Reconnect all modules and restore battery power.

4. 4

   Programming

   If the BCM was replaced, connect the Case IH Electronic Service Tool (EST) / CNH diagnostic software. Perform the 'WRITE CONFIGURATION' procedure to upload the specific vehicle specification file to the new BCM.

5. 5

   Clear Codes

   Clear all stored and pending DTCs using the scan tool. Cycle the key and verify that fault code 520330-14 does not return.