New Holland ENG 3870 – Engine Control Module (ECM): CAN Bus Communication: CAN message not received from Vehicle Controller (BC2EDC1)

The Engine Control Module (ECM) has stopped receiving the expected BC2EDC1 data packet from the main vehicle controller over the CAN bus network.

• Skid Steer Loaders (SSL)
• Compact Track Loaders (CTL)
• Wheel Loaders (W190B, 721F, 821F, 921F)
• New Holland T6
• New Holland T7
• New Holland T8
• Boomer series

1. 1

   Connect the CNH Electronic Service Tool (EST) to confirm the fault code is currently active, not just a stored historical code.

2. 2

   Check power and ground to ensure the Vehicle Controller (UCM/Instrument Cluster) is powering up correctly.

3. 3

   Inspect the CAN High and CAN Low wires between the Vehicle Controller and the Engine ECM for open circuits, short circuits to ground, or short circuits to battery voltage.

4. 4

   Measure the CAN bus network resistance with a multimeter (should read approximately 60 ohms; 120 ohms indicates a broken/missing terminating resistor, 0 ohms indicates shorted CAN wires).

5. 5

   Check the harness connectors at both the ECM and the Vehicle Controller for pushed-out pins, corrosion, or water intrusion.

1. 1

   Disconnect Power

   Turn off the machine and disconnect the negative battery cable to prevent electrical spikes.

2. 2

   Access the Modules

   Locate the Engine ECM (usually mounted on the side of the engine block) and the Vehicle Controller/UCM (usually located in the cab console or under the dash).

3. 3

   Clean and Reseat Connectors

   Disconnect the wiring harnesses from both modules. Spray the pins with electrical contact cleaner, ensure no pins are bent, and firmly reseat the connectors. Sometimes, fretting corrosion causes temporary CAN timeouts.

4. 4

   Repair Wiring

   If the diagnostic continuity tests revealed an open or shorted CAN wire, splice and repair the damaged section of the wiring harness using OEM-approved heat-shrink connectors, or replace the harness section.

5. 5

   Clear Codes and Test

   Reconnect the battery, turn the key to the ON position, and use the CNH EST diagnostic tool to clear the 3870 fault code. Start the engine and operate the machine to see if the code returns.

6. 6

   Module Replacement

   If the wiring and terminating resistors are perfectly intact but the ECM still cannot see the Vehicle Controller, the Vehicle Controller (UCM) or the Engine ECM has suffered an internal hardware failure and must be replaced.