John Deere 523694.19 – SCC (Rear Chassis Control Unit) / SCU: SV II (or SCV II) External Control Fault Message Received

This is a CAN BUS communication error indicating that the controller has received a message with a failure indication regarding the external control command for Selective Control Valve #2 (SCV II). This typically happens when the external SCV control lever, fender switch, or a connected implement's external control sends corrupted data, fails, or experiences a wiring issue on the CAN bus network.

• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R
• 9230
• 9330
• 9430
• 9530
• 9630
• 9360R
• 9410R
• 9460R
• 9510R
• 9560R
• 8310RT
• 8335RT
• 8360RT
• 7720
• 7820
• 7920
• 7810

1. 1

   Restart the tractor to verify if the active Service Code reappears, as the code can sometimes be corrected by resetting communication messages during a power cycle.

2. 2

   Disconnect any implement connected to the tractor that utilizes external SCV II control to determine if the fault originates from the implement's wiring.

3. 3

   Visually inspect the external SCV II control switch (often located on the rear fender) and its wiring harness for physical damage, accumulated debris, or moisture.

4. 4

   Check for other related SCC/SCU codes (such as missing messages or voltage supply faults) which might indicate a broader chassis harness failure rather than an isolated switch failure.

1. 1

   Isolate the Implement

   Disconnect any implement wiring harnesses from the rear of the tractor. Clear the codes and cycle the key. If the code does not return, repair the implement's external control wiring.

2. 2

   Inspect the Chassis Harness

   If the code persists on the bare tractor, trace the wiring harness from the SCV II external control switch (fender switch) back to the Rear Chassis Control Unit (SCC).

3. 3

   Test the External Switch

   Check the SCV II external control switch for proper resistance/continuity. If the switch has failed internally and is broadcasting a corrupted CAN message, replace the switch.

4. 4

   Repair Wiring

   If the switch tests good, look for chafed wires or corroded pins at the SCC connectors. Repair any damaged CAN bus wiring between the switch and the SCC.

5. 5

   Module Replacement/Reprogramming

   If the wiring and switches are perfectly intact and the code remains active, the SCC module itself may have an internal fault. Have a John Deere dealer test the SCC; it may require a software reflash or complete replacement.