Case IH F-639-31 - ECU – Engine Control Unit (ECU A-095): CAN A Bus off failure

CAN communication has been interrupted and the CAN controller has been forced into a "bus off" state. This is typically caused by erroneous behavior of a participant on the network, or a short circuit in the CAN A Bus circuits (short to an external power source, short to ground, or short to CAN High).

• MAGNUM AFS Connect
• Magnum MX210
• Magnum MX230
• Magnum MX255
• Magnum MX285
• Axial-Flow 240 Series

1. 1

   Check the presence and correct connection of the ECU to the network, ensuring all connectors are completely seated.

2. 2

   Visually inspect the wiring harnesses and connectors for damaged, bent, or displaced pins, corroded terminals, or broken wires.

3. 3

   Test the CAN A Bus circuits for shorts to an external source, shorts to ground, or shorts to CAN High.

4. 4

   Check the CAN termination resistors to ensure proper resistance (ECU A-095 provides a termination resistor for the CAN Node A Bus).

5. 5

   Flex the involved harnesses while operating the machine and observing the monitor to reveal intermittent breaks or shorts in the wiring.

1. 1

   Resolve Wiring Issues

   If the diagnostic checks reveal any damaged wiring, corroded pins, or short circuits in the CAN A Bus lines, repair or replace the affected section of the wiring harness.

2. 2

   Software Verification

   If the wiring and connections are intact but the fault has not been resolved, verify that the appropriate software for ECU A-095 is present. Reinstall or flash the ECU software if necessary.

3. 3

   Module Replacement

   If the wiring is verified good, the termination resistors are within spec, and software updates do not resolve the "bus off" state, the ECU A-095 itself has likely suffered an internal hardware failure and must be replaced.