Case IH 14013 – ICU (Instrument Control Unit): TRANSMISSION Off Line

This is a CAN bus communication error indicating that the main vehicle network has lost communication with the Transmission Control Unit (TCU).

• Magnum
• Steiger T4B
• Case IH Magnum 235 - 340 (Series 4)
• Case IH Steiger Series (350, 400, 450, 500, 550, 600)
• Case IH Puma Series

1. 1

   Check for associated codes (such as 14011 - Communications Lost with Vehicle Data Bus 1) to determine if multiple modules are offline, indicating a main CAN backbone failure rather than an isolated TCU issue.

2. 2

   Inspect the TCU connectors (e.g., C202 or the main transmission harness connectors) for bent pins, pushed-out terminals, corrosion, or moisture.

3. 3

   Verify power and ground to ensure the Transmission Control Unit is receiving proper operating voltage. Check for a blown fuse, open power circuit, or bad ground.

4. 4

   Test the CAN Bus by measuring the resistance across the CAN High and CAN Low pins to check for harness continuity and ensure the terminating resistors are intact.

1. 1

   Power Cycle and Clear

   Turn off the machine, wait for the modules to power down completely, and restart. Use an Electronic Service Tool (EST) to see if the code is active or stored.

2. 2

   Harness Inspection

   Trace the wiring harness from the ICU to the TCU. Look for pinch points, chafing, or melted wires, particularly near the transmission housing and articulation joints (on Steiger models).

3. 3

   Connector Repair

   If the CAN bus connector at the TCU is damaged, cut back the damaged wire and install a new connector or replacement pins.

4. 4

   Restore Power/Ground

   If the TCU is not receiving power, trace the power supply wire back to the fuse panel and replace any blown fuses or repair broken supply wires.

5. 5

   Module Replacement

   If the wiring harness is intact, the connectors are clean, and the TCU has verified power and ground but still will not communicate, the TCU has suffered an internal hardware failure. Replace the Transmission Control Unit and program it using the dealer EST tool.