John Deere 1231.14 – TEC, RLC, VCU, or CCU: CAN Bus High Error Rate, Error Limit Exceeded, or "Bus Off" condition

The control software has detected too many incorrect or dropped CAN Bus messages (often on CAN Bus 2, the Implement CAN Bus, or the Drive Train CAN Bus). When the error rate exceeds the programmed threshold, the controller shuts down communication on that bus to prevent network corruption, resulting in limited or no functionality for the affected systems.

• 6110M
• 6120M
• 6130M
• 6145M
• 6155M
• 6175M
• 6195M
• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R
• 6230
• 6330
• 6430
• 7230
• 8R/8RT Series (8245R–8400R)
• 9030 Series (9330, 9430, 9530, 9630)
• 744K
• 204L
• 304L
• 260E
• 310E
• 370E
• 410E
• 460E

1. 1

   Isolate the Implement: Disconnect any ISOBUS implements from the tractor. If the code goes to an inactive state, the fault is in the implement's wiring or an incompatible non-ISO device is crashing the bus.

2. 2

   Inspect CAN Bus Wiring: Visually inspect the CAN Bus wiring harness (specifically CAN 2 / Implement Bus) for chafing, pinched wires, or corrosion at the connectors.

3. 3

   Check Terminating Resistors: With the battery disconnected, measure the resistance across the CAN High and CAN Low pins at the diagnostic connector. A healthy CAN bus should read approximately 60 ohms. If it reads 120 ohms, one terminating resistor is missing or broken. If it reads 0 ohms, there is a short circuit.

4. 4

   Check Module Power/Ground: Verify that the TEC (or logging module) is receiving proper battery voltage and has a clean ground connection.

1. 1

   Disconnect Power

   Turn off the key switch and disconnect the negative battery cable.

2. 2

   Clean Connections

   Disconnect the main harness to the TEC (or the specific module logging the fault, such as the RLC). Spray the pins with electrical contact cleaner and check for pushed-back pins or moisture intrusion.

3. 3

   Repair Harness

   If the multimeter test revealed a short or open circuit in the CAN lines, trace the harness along the chassis (or up the cab pillars if it's the RLC) and splice/repair the damaged CAN High (usually yellow) or CAN Low (usually green) wires using OEM-approved weather-sealed connectors.

4. 4

   Replace Terminating Resistor

   If the bus resistance was incorrect and wiring is intact, locate and replace the faulty CAN terminating resistor.

5. 5

   Clear Codes and Test

   Reconnect the battery, turn the key on, and use John Deere Service ADVISOR (or a compatible diagnostic tool) to clear the inactive 001231.14 code. Run the machine to verify the code does not return.

6. 6

   Module Replacement (Last Resort)

   If the wiring, resistors, and implement are all in perfect condition but the module continues to drop off the bus, the TEC or RLC itself has an internal hardware failure and must be replaced and reprogrammed by a dealer.