Case IH 1920-02 - UCM – UCM: Vehicle controller loss of communication with rear pilot head #1

The vehicle's controller (UCM) has lost CAN bus communication with the electronic pilot actuator (solenoid head) on Rear Remote Valve #1 (Auxiliary Valve 1). The FMI 02 designation indicates data that is erratic, intermittent, or incorrect.

• MAGNUM AFS Connect
• Magnum
• Steiger
• Puma
• Optum

1. 1

   Inspect the wiring harness at the rear of the tractor leading to Rear Remote #1 for obvious cuts, unplugged connectors, or crushed wires.

2. 2

   Unplug the connector at the UCM and at the rear remote valve to check for water ingress, dirt, or corroded pins.

3. 3

   Check the CAN High and CAN Low voltages to ensure the circuit is not shorted, and measure the CAN termination resistance at the UCM.

4. 4

   Verify that the UCM is sending the correct reference voltage (typically 5V or 12V) and has a solid ground to the valve actuator.

1. 1

   Power Down

   Turn off the tractor and disconnect the battery to prevent electrical spikes.

2. 2

   Clean and Reconnect

   If moisture or dirt was found in the connector for Remote Valve #1, clean the pins with electronic contact cleaner, apply dielectric grease, and reconnect.

3. 3

   Harness Repair

   If the CAN bus wiring is damaged between the UCM and the valve, splice and heat-shrink the damaged section or replace the remote valve harness pigtail.

4. 4

   Actuator Replacement

   If the wiring and UCM outputs test good but communication is still lost, the electronic pilot head (actuator) on Rear Remote #1 has failed internally and must be replaced.

5. 5

   Clear Codes

   Reconnect the battery, cycle the key, and use the Case IH Electronic Service Tool (EST) to clear the UCM fault codes and verify that Aux Valve 1 responds to in-cab commands.