John Deere 002000.09 – CMU, EMU, ACU, or MCZ: CAN BUS Message Issue With Communication Between the Engine Module and the Main Controller

The fault code 002000.09 indicates a critical communication failure on the Controller Area Network (CAN) bus where a primary controller has not received expected data messages from the Engine Control Unit (ECU). This loss of communication prevents the exchange of essential operational data, which can lead to symptoms like a no-start condition, engine shutdown, or loss of power.

• 3033R
• 2038R
• 3046R
• 4044M
• 6170R
• 7330
• 7530
• 323D
• 323E
• 326D
• S690
• 640H
• 648H
• 850J
• 130G
• 200D
• 200DLC
• 870GLC

1. 1

   Inspect and test fuses related to the ECU and controllers (e.g., the 20-amp mini fuse located near the battery, or F3 on a 323D)

2. 2

   Inspect battery and ground connections, ensuring terminals are clean and tight. Specifically check the small red wire attached to the positive battery cable for a solid connection

3. 3

   Visually inspect the CAN bus wiring harness and connectors on the ECU, monitoring controller, and inline connectors for cuts, abrasions, rodent damage, corrosion, pushed-back pins, or loose connections

4. 4

   Test CAN bus voltages using a multimeter. With the key on, measure approximately 2.5 volts on both the CAN High (yellow) and CAN Low (green) wires relative to a good ground

5. 5

   Check CAN bus termination resistors. With the machine powered off, measure resistance between the CAN High and CAN Low pins; a healthy bus should read approximately 60 ohms

6. 6

   Use John Deere Service ADVISOR (if available) to check the ECU software version and controller status

1. 1

   Address basic power issues

   Replace any blown fuses and clean or tighten any loose battery or ground connections identified during the initial checks.

2. 2

   Repair wiring and connectors

   If any damaged wiring or corroded connectors are found, repair or replace them. Ensure all connector pins are properly seated and making good contact. Clear the codes and see if the fault returns.

3. 3

   Reprogram controller

   If diagnostic checks on wiring and power are inconclusive, use the John Deere Service ADVISOR software to reprogram the controller that logged the code (e.g., the CMU).

4. 4

   Isolate and test controllers

   If the problem persists, swap the suspect ECU or monitoring controller with a known good unit from an identical machine, if possible, to see if the problem follows the controller.

5. 5

   Replace the faulty controller

   If reprogramming fails or if a controller is identified as faulty during isolation testing, replace it. In many cases, the ultimate failure lies with the ECU itself.