John Deere 002000.09 – ECU: CAN BUS Message Fault

A communication failure has been detected on the Controller Area Network (CAN) bus within the Main Control Module (TIQ) or Engine Control Unit (ECU). The ECU is not properly sending or receiving data messages to and from other control modules on the machine's network. This disruption affects the proper exchange of data between systems and can lead to operational disruptions, including a no-start condition where the engine cranks but receives no fuel, or the machine stopping unexpectedly during operation.

• 3033R
• 3046R
• 2038R
• 7330
• 323D
• 326D
• S690
• 850J

1. 1

   Inspect the ECU fuse, often a 20-amp fuse. On some models like the 3033R, check the 20-amp mini fuse located in a black holder near the battery

2. 2

   Check the small red wire attached to the positive battery cable clamp to ensure it is secure, not corroded, and has a solid connection

3. 3

   Examine all CAN bus wiring and connectors for damage, corrosion, loose/pushed pins, or rodent damage (pay close attention to connectors behind the monitor, at the rear of the cab, and at the main ECU)

4. 4

   Test CAN bus voltage using a multimeter; the CAN High wire (yellow) and CAN Low wire (green) should both read approximately 2.5 volts

5. 5

   Check for active versus stored codes, as the issue can be intermittent and sometimes clears after a restart

6. 6

   Access the controller information via the machine's display to verify if the correct ECU software information is present

1. 1

   Address immediate wiring or fuse issues

   If diagnostic checks reveal a blown fuse, corroded connector, or loose wire, rectify it first. Replace the fuse, clean connector pins with a wire brush and apply dielectric grease, or repair damaged wires. If the small red battery wire is loose, cut it, fit a new eyelet, and reattach firmly.

2. 2

   Perform a system reset

   Attempt to clear the fault code and perform a system reset or a cold boot to see if the intermittent issue is resolved.

3. 3

   Perform CAN circuit continuity test

   If the code persists, check for continuity on the CAN High and Low wires between the ECU and other modules to locate any open circuits or shorts.

4. 4

   Reprogram controller

   If wiring and connections are confirmed to be good, the issue may be software-related. Reprogram the CAN monitor unit (CMU) or the ECU with the latest software.

5. 5

   Replace faulty components

   If tests point to a specific sensor (e.g., crankshaft or throttle position sensor) sending faulty data, replace it. If CAN bus wiring is intact and reprogramming fails, the ECU or CMU itself may be faulty and will need to be replaced or rebuilt.