Case IH 12671 – ABS Controller / Trailer Brake Controller: Internal controller fault - number of ICC communications in 1 second out of range

A Controller Area Network (CAN bus) communication anomaly where the affected controller detects that the number of messages or connections received from the ICC within a 1-second window is either too high (data flood/short) or too low (dropped packets/timeout).

• Puma
• Magnum
• Optum
• T7
• T8

1. 1

   Check battery health and clean main chassis grounds, as low voltage at startup can cause modules to drop offline.

2. 2

   Inspect the CAN bus wiring (typically yellow and green wires) between the ABS controller and the ICC for chafing, cuts, or corrosion.

3. 3

   Inspect the housing and pins at both the ABS module and the ICC for water ingress, bent pins, or corrosion.

4. 4

   Verify the CAN bus termination resistors are intact and not pulling the bus voltage down.

5. 5

   Connect a diagnostic tool (PRO 700 display or CNH EST) to see if other modules are reporting CAN communication errors (e.g., SPN 639).

1. 1

   Power Down

   Turn off the machine and disconnect the negative battery terminal to prevent electrical shorts during repair.

2. 2

   Clean and Reseat Connectors

   Disconnect the harnesses at the ABS controller and the ICC. Clean the contacts with electronic contact cleaner. Apply a light coat of dielectric grease to prevent future moisture intrusion, and firmly reseat the connectors.

3. 3

   Repair Wiring

   If chafed or broken CAN wires were found during the diagnostic phase, splice and seal the wires using OEM-approved heat-shrink connectors.

4. 4

   Module Replacement

   If the wiring, grounds, and voltage are all within specification (CAN bus voltage should be roughly 2.4V - 2.5V on the data lines), the ABS controller has suffered an internal hardware failure and must be replaced.

5. 5

   Clear Codes and Calibrate

   Reconnect the battery. Use the diagnostic scanner to clear the 12671 fault code. Perform a test drive to ensure the ABS module communicates properly with the ICC and the code does not return.