John Deere 1231.12 – CCU, TEC, or TEI: Vehicle CAN BUS, High Error Rate / Tractor CAN Message Overflow

Communication failure or message overload on the 29-bit Tractor CAN Bus, most commonly caused by a mixture of ISO compliant and non-compliant devices connected to the implement connector.

• 6110M
• 6120M
• 6130M
• 6145M
• 6155M
• 6175M
• 6195M
• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R
• 6M Series
• 6R Series
• 6215M
• 6030 Series
• 6230
• 6330
• 6430
• 6J Series
• 7J Series
• 6145J
• 6205J
• 7185J
• 7225J
• 9030 Series
• 9230
• 9330
• 9430
• 9530
• 9630
• 4WD Loaders
• 744K Series II
• Articulated Dump Trucks
• E-Series Excavators
• E300LC
• E360

1. 1

   Verify if any new or non-OEM implements were recently connected to the ISOBUS/implement connector, looking for a mixture of ISO-compliant and non-compliant devices

2. 2

   Check for companion codes that pinpoint the issue, such as 522550.14 (Implement Connected to ISOBUS is Not Compatible) or 523652.02 (Controller Connected to Wrong Wiring Harness Connector)

3. 3

   Inspect the CAN bus wiring harness, specifically the implement connector at the rear of the tractor, for corrosion, bent pins, or moisture intrusion

4. 4

   Cycle the key switch to see if the message overflow was a temporary software glitch

1. 1

   Isolate the Implement

   Disconnect all devices and implements from the tractor's ISOBUS implement connector.

2. 2

   Reset the System

   Cycle the tractor's key switch off, wait 30 seconds, and turn it back on. Clear the stored diagnostic trouble codes using the CommandCenter or Service ADVISOR.

3. 3

   Test for Recurrence

   If the code does not return, the fault lies with the disconnected implement (likely a non-compliant ISO device). If the code returns immediately with nothing connected, the fault is on the tractor side.

4. 4

   Wiring Repair

   Use a multimeter to test the CAN bus terminating resistors (should read ~60 ohms across CAN High and CAN Low). Repair or replace any damaged sections of the CAN bus wiring harness.

5. 5

   Module Reprogramming/Replacement

   If the wiring is intact, the CCU, TEC, or TEI module may have an internal fault or corrupted software. Connect John Deere Service ADVISOR, flash the module with the latest software update, and recalibrate. If the module will not accept the flash or the internal CAN transceiver is burnt out, replace the control unit.