John Deere 523769.31 – CCU (Chassis Control Unit) / BCU (Basic Control Unit): CAN BUS Message Fault Rear Chassis / Front-Wheel Drive Switch Fault

Depending on the tractor series, this code indicates either a communication failure on the CAN bus receiving incorrect or missing messages from the rear chassis module, or an electrical fault in the switch circuit that engages the Mechanical Front-Wheel Drive (MFWD).

• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R
• 6090MC
• 6100MC
• 6110MC
• 6090RC
• 6100RC
• 6110RC
• 6145J
• 6165J
• 6180J
• 6205J

1. 1

   Check for companion codes on the display, as CAN bus faults are frequently accompanied by other module communication errors or wheel speed sensor faults

2. 2

   For 6R Series (CAN fault cause): Inspect the CAN bus wiring harness and connectors at the rear chassis and the CCU for chafing, corrosion, or loose pins

3. 3

   For 6MC/6RC/6J Series (MFWD switch cause): Test the front-wheel drive rocker switch on the console for proper continuity and verify the wiring integrity between the switch and the CCU/BCU

4. 4

   Verify the CCU/BCU software version, as logic-based faults may be resolved by reprogramming

1. 1

   Power Down

   Turn off the ignition and disconnect the battery before servicing the electrical system or CAN bus network to prevent module damage.

2. 2

   Address the CAN Bus (6R Series)

   Locate the rear chassis harness connectors and the CCU. Disconnect, inspect, clean with contact cleaner, and securely reconnect them. Repair any damaged CAN wiring (CAN High / CAN Low) in the rear chassis harness.

3. 3

   Address the MFWD Switch (6MC/6RC/6J Series)

   Remove the console trim to access the MFWD switch. Perform a multimeter continuity test on the switch pins while toggling it. If the switch fails the continuity test, replace it.

4. 4

   Software Flash

   If the physical wiring and switches are intact, connect the John Deere Service ADVISOR diagnostic tool. Reprogram the CCU/BCU using the latest software file and perform any necessary configurations and calibrations.

5. 5

   Clear Codes

   Delete the diagnostic trouble codes (DTCs) from the system memory.

6. 6

   Verify Repair

   Restart the tractor, test drive it, and verify that the code does not return and that the rear chassis modules/MFWD operate correctly.