John Deere 522578.09 – Rear Chassis Control Unit (CCU): CAN BUS Message Issue With Communication Between the Modules. Check for Other Codes Rear Chassis (CCU)

Communication failure or abnormal update rate (FMI 09) on the Controller Area Network (CAN BUS). Expected data messages are not being successfully transmitted or received between the cab modules and the Rear Chassis Control Unit.

• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R
• 6110M
• 6120M
• 6130M
• 6145M
• 6155M
• 6175M
• 6195M

1. 1

   Check for other active codes — a single failed sensor or secondary module can crash the CAN BUS; resolving other codes often clears the communication issue

2. 2

   Perform the Rear Chassis Control Unit Sensor Supply (1, 2, 3, and 4) Power and Ground Circuit Tests to ensure the CCU is receiving adequate voltage

3. 3

   Inspect the CAN BUS network by checking the CAN High and CAN Low lines for proper voltage and testing the CAN BUS terminating resistors

4. 4

   Visually inspect the Rear Chassis Harness for chafing, pinched wires, or loose connections

5. 5

   Check the main ground connections near the battery and the 250-amp fuse

1. 1

   Disconnect Power

   Disconnect the battery before servicing the electrical system or unplugging modules.

2. 2

   Clean CCU Contacts

   Locate the Rear Chassis Control Unit (CCU). Unplug the harness connectors and inspect the pins for moisture, corrosion, or damage. Clean the contacts on the CCU thoroughly.

3. 3

   Test the Rear Chassis Harness

   Using a multimeter, check for continuity on the CAN High and CAN Low wires between the CCU and the cab interface. If resistance is out of spec or a short to ground is found, locate the break in the Rear Chassis Harness and repair the wiring.

4. 4

   Check Terminating Resistors

   If the wiring is intact, locate and test the CAN BUS terminating resistors. If a resistor has failed (open circuit), replace it.

5. 5

   Module Replacement/Reprogramming

   If the wiring harness, grounds, and terminating resistors all test good, the CCU itself may have suffered an internal failure. At this stage, the CCU must be replaced or reprogrammed, which requires a John Deere dealer.

6. 6

   Clear Codes

   Reconnect the battery, cycle the key, and clear the stored fault codes to verify the repair.