John Deere 2040.09 – ECU, BIF, PDU, ADU, or CLC: CAN BUS Communication Failure

A control module on the machine's Controller Area Network (CAN) has stopped receiving expected data packets from another module (often Source Address 40). The network is experiencing data transmission issues, which are most commonly caused by wiring faults, failed terminating resistors, or a module losing power/ground.

• 5085E
• 5090E
• 5090EL
• 5100E
• 5085M
• 5100M
• 5100MH
• 5100ML
• 5115ML
• 5090M
• 5115M
• 6090MC
• 6100MC
• 6230
• 6330
• 6430
• 8245R
• 8310R
• 8400R
• 624K
• 744K
• 824K
• 770G
• 772G
• 330LC-8B
• 160DLC

1. 1

   Check for other active codes across multiple modules to trace the dead branch of the network.

2. 2

   Perform a cold boot by cycling the key switch and battery disconnect switch to see if communication is restored.

3. 3

   Test CAN voltage with the key ON (CAN High should read 2.5V to 2.6V, CAN Low should read 2.4V to 2.5V).

4. 4

   Test CAN resistance with the battery disconnected (should read exactly 60 Ohms; 120 Ohms indicates a missing or failed resistor, 0 Ohms indicates a short).

5. 5

   Verify that the ECU and the Main Controller are receiving stable 12V power and have clean grounds.

1. 1

   Disconnect Power

   Turn off the machine and disconnect the negative battery cable to prevent electrical shorts during inspection.

2. 2

   Inspect the Harness

   Trace the CAN bus wiring harness (specifically the twisted Yellow and Green wires) between the ECU and the cab/main controller. Look for chafing, crushed sections, or areas where the harness rubs against the chassis.

3. 3

   Clean Connectors

   Disconnect the harness connectors at the ECU and the cab bulkhead. Inspect for pushed-back pins, corrosion, or water ingress. Clean the pins with electronic contact cleaner and apply dielectric grease before reconnecting.

4. 4

   Replace Terminating Resistors

   If your resistance test yielded 120 Ohms, locate the CAN bus terminating resistors (usually located at the extreme ends of the wiring harness, sometimes near the ECU and behind the cab display). Replace the faulty resistor.

5. 5

   Repair Wiring

   If a break or short is found in the CAN wires, repair it using approved twisted-pair splicing methods (maintaining the twist as close to the splice as possible to prevent electromagnetic interference).

6. 6

   Software Update

   Reconnect the battery. If the wiring and resistors are perfect, the issue may be a firmware bug causing message timeouts. A John Deere dealer may need to flash the ECU and Main Controller with the latest software.