John Deere 516123.31 – CCU (Chassis Control Unit / Rear Chassis): LIN BUS Communication Issue With Battery Cut Off Relay Rear Chassis (CCU)

Loss of communication on the LIN (Local Interconnect Network) bus between the control module and the battery cut-off relay. This failure typically results in sudden power loss, intermittent electrical issues, or a 'no-start' condition due to the relay cutting off battery power unexpectedly.

• 6110M
• 6120M
• 6130M
• 6145M
• 6155M
• 6175M
• 6195M
• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R
• 7R Series Tractors
• S700 Series Combines

1. 1

   Use a comprehensive OBD-II/John Deere diagnostic scanner to confirm 516123.31 is the active code and check for any other related communication codes.

2. 2

   Physically inspect the LIN bus wiring harness leading to the battery cut-off relay for frayed wires, physical damage, or loose connections.

3. 3

   Inspect the 5-pin relay socket and connectors for moisture, dirt, or corrosion, which can interrupt the low-voltage LIN communication signals.

1. 1

   Power Down

   Ensure the tractor is turned off and the key is removed from the ignition.

2. 2

   Locate the Relay

   Locate the battery cut-off relay connected to the rear chassis control unit (CCU) harness.

3. 3

   Remove the Faulty Relay

   Unplug the existing 5-pin battery cut-off relay from its socket.

4. 4

   Install the Replacement

   The replacement relay is a plug-and-play 5-pin design. Align the pins (OEM-precise dimensions) and press the new relay firmly into the socket until fully seated.

5. 5

   Clear Codes and Test

   Reconnect diagnostic equipment, clear the 516123.31 fault code from the CCU, and start the machine to verify that power is maintained and the code does not return.