Case IH 2290 (520329.02) - DEC – ECCU, ARU, Engine ECU (EDC), or FMGR: CAN 1 - Bus Off

A severe physical disruption or communication failure on the Controller Area Network (CAN) 1 bus lines. The CAN controller has detected excessive transmission errors and forced itself into a "Bus Off" state to prevent sending corrupted data.

• MAXXUM T4E
• VESTRUM CVX
• Case IH tractors

1. 1

   Visually inspect the CAN 1 cables and wiring harnesses at the reporting ECU (e.g., Armrest module or ECCU) for chafing, severed wires, or physical damage

2. 2

   Verify the J1939 network backbone and stub connections to each ECU, ensuring connectors are fully seated and free of corrosion or water intrusion

3. 3

   Verify that the terminating resistors on the CAN network are correct and intact

4. 4

   Check the CAN bus for short circuits and verify the shielding of the cables to ensure strong magnetic fields are not disrupting the bus

5. 5

   Verify that the engine, display, and other modules are powering up and attempting to communicate on the J1939 network

1. 1

   Power Down

   Turn off the machine's ignition and disconnect the battery to prevent electrical shorts during testing.

2. 2

   Isolate the Fault

   Disconnect the CAN 1 trunk connections one at a time to isolate which half of the system or which specific stub is causing the bus to short.

3. 3

   Test Wiring

   Using a multimeter, check for continuity on the CAN High and CAN Low lines. Test for a short to ground, a short to power, or a short between the two CAN lines.

4. 4

   Repair Harness

   If a wire is broken or shorted, repair the wiring harness using an approved CAN wiring repair kit, ensuring the twisted pair configuration is maintained to prevent interference.

5. 5

   Replace Terminating Resistors

   If the network resistance is out of spec (it should typically read ~60 ohms with both 120-ohm resistors in place), replace the faulty terminating resistor.

6. 6

   Reassemble and Clear

   Reconnect all ECU connectors securely. Reconnect the battery, turn the ignition on, and use the CNH Electronic Service Tool (EASY) to clear the fault codes and verify that CAN 1 communication has been restored.