Case IH 518406-09 - UCM – UCM: Vehicle controller communication fault with display

The Universal Control Module (UCM) has lost Controller Area Network (CAN) bus communication with the tractor's primary cab display.

• MAGNUM AFS Connect
• Case IH Magnum AFS Connect Series (Models 180, 200, 220, 240, 250, 280, 310, 340, 380, and 400)
• Case IH Steiger / Quadtrac AFS Connect Series

1. 1

   Verify that the tractor's battery voltage is within the normal operating range, as low voltage can cause initialization failures.

2. 2

   Inspect the implement/vehicle CAN bus lines between the UCM and the AFS Pro 1200 display for loose, intermittent, or corroded connections.

3. 3

   Verify that the CAN bus is properly terminated by measuring resistance across CAN High and CAN Low with the battery disconnected (should be approximately 60 ohms).

4. 4

   Use the Case IH Electronic Service Tool (EST) to check for mismatched or outdated software versions on the UCM and the AFS Pro 1200 display.

1. 1

   Disconnect Power

   Turn off the machine and disconnect the battery to prevent electrical spikes during harness inspection.

2. 2

   Inspect Harness Connections

   Locate the UCM (often mounted under the cab or near the transmission housing, depending on the exact model) and the back of the AFS Pro 1200 display. Disconnect the main harness connectors.

3. 3

   Clean and Reseat

   Inspect the pins for pushed-back terminals, moisture, or corrosion. Clean the contacts with electronic contact cleaner and firmly reseat the connectors.

4. 4

   Test Wiring Continuity

   If the fault persists, use a multimeter to perform a continuity test on the CAN High and CAN Low wires from the UCM interface harness to the display harness. Repair any breaks or shorts to ground.

5. 5

   Update Software

   Reconnect the battery. Connect the Case IH EST and flash the UCM and the display to the latest software versions (e.g., UCM software version 15.2.0.0 or newer, depending on the specific Magnum/Steiger tier).

6. 6

   Clear and Retest

   Clear the fault code via the EST. Cycle the key. If the code returns immediately and the wiring harness is 100% verified, the UCM or the display itself has suffered an internal hardware failure and must be replaced.