Fendt 1.2.70 – Engine Control Unit (ECU) / EDC / EMR / EMR2: ECU, EDC — CAN Bus controller fault

The CAN bus controller inside the engine management system has failed or is experiencing severe communication errors on the network, which may result in reduced engine running characteristics.

• 409 Vario
• 410 Vario
• 411 Vario
• 412 Vario
• 711 Vario
• 712 Vario
• 714 Vario
• 715 Vario
• 716 Vario
• 717 Vario
• 718 Vario
• 916 Vario
• 920 Vario
• 924 Vario
• 926 Vario
• 930 Vario
• all Vario tractors
• Fendt 300 Vario (COM III)
• Fendt 400 Vario / Farmer 400
• Fendt 700 Vario / Favorit 700
• Fendt 800 Vario
• Fendt 900 Vario / Favorit 900

1. 1

   Check the transmission bus terminating resistors to ensure they are preventing signal reflection

2. 2

   Test Component A013 (terminating resistor located on the circuit board)

3. 3

   Test Component A009 (terminating resistor located at the actuator unit / positioner)

4. 4

   Check the ECU EMR2 for power, ground, and connector pin integrity

1. 1

   Power Down

   Turn off the tractor and disconnect the battery to safely test the CAN network resistance.

2. 2

   Measure CAN Resistance

   Using a multimeter, measure the resistance across the CAN High and CAN Low pins at a diagnostic port. A healthy CAN bus should read approximately 60 ohms (two 120-ohm resistors in parallel).

3. 3

   Inspect Terminating Resistors

   If the reading is 120 ohms or higher, the network is missing a resistor. Locate the A013 circuit board and the A009 actuator unit. Unplug them and test their internal resistance. Replace whichever component has a burnt or open resistor circuit.

4. 4

   Inspect Wiring

   Check the twisted-pair CAN wiring between the EDC/EMR2 module and the transmission bus for chafing, corrosion, or breaks.

5. 5

   ECU Replacement

   If the terminating resistors are intact (60 ohms on the network) and the wiring harness passes a continuity test, the CAN controller internal to the EDC/EMR2 ECU has failed. The engine control unit will need to be replaced and reprogrammed (EOL programming) to match the tractor.