Case IH 3877 – Vehicle Controller and ECU: CAN communication failure between vehicle controller and ECU - BC2ECU1 message

The primary Controller Area Network (CAN) bus circuit has lost communication or timed out when attempting to exchange the BC2ECU1 data message between the vehicle's main management computer and the engine controller.

• Steiger T4B
• 240 Series Axial-Flow® Combines

1. 1

   Verify that the fault code is currently active before tearing down components.

2. 2

   Check battery condition and charging system voltage, as low voltage can trigger false CAN bus codes.

3. 3

   Inspect the primary CAN bus wiring and connectors for moisture intrusion or aging.

4. 4

   Check for a failed terminating resistor on the CAN network.

1. 1

   Confirm the fault

   Turn on the machine and verify if DTC 936B is currently active.

2. 2

   Test the power supply

   Test the battery and charging system to ensure proper voltage is reaching the electronic control units.

3. 3

   Perform a visual and physical inspection

   Conduct a thorough inspection of the connector housings, especially if operating in humid climates. Look for moisture, corrosion, or backed-out pins in the wiring harness between the vehicle controller and the ECU. Clean and dry any affected connectors.

4. 4

   Test the CAN bus circuit

   Use a multimeter to test the CAN bus circuit for wiring continuity problems or a failed terminating resistor.

5. 5

   Module Replacement (Last Resort)

   Do not replace the ECU or vehicle controller until you have fully verified the battery condition, charging voltage, wiring integrity, and CAN bus communication. If all wiring and resistors pass inspection, the fault lies within the internal transceiver of the ECU or Vehicle Controller.