Fendt A004 – Operating Console: Control Console CAN-Bus Fault

Fault code A004 indicates a problem originating from or related to the A004 Control Console (side console). This represents a category of faults rather than a single issue, encompassing internal electronic failures (RAM/EEPROM), general bus communication loss on the Enhanced Control Bus (K-Bus/Comfort-BUS), specific CAN bus communication failures between the A002 ECU and A004 console, component signal faults from console switches, or power supply issues. These failures can result in a loss of console functions, blank displays, or restricted operating modes.

• Farmer 400 Vario
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• Farmer 412 Vario
• Favorit 700 Vario
• Favorit 900 Vario
• 300 Vario
• 700 Vario
• 800 Vario
• 900 Vario
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• COM III
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• 716 Vario TMS
• 818 Vario TMS
• 820 Vario TMS
• Farmer 300 Series

1. 1

   Check fuses F040 and F041 on the A013 circuit board, which supply power to the control console's CAN bus

2. 2

   Ensure the battery voltage is stable and strong, as low voltage can cause intermittent communication errors, and check for clean, tight connections at the battery terminals

3. 3

   Carefully inspect the wiring harnesses connected to the control console for chafing, pinching, or heat damage

4. 4

   Check for corroded or loose electrical connectors at the back of the console and on the A013 fuse board

5. 5

   Verify that the main chassis and cab grounding points are clean, tight, and free of corrosion

1. 1

   Disconnect battery

   Disconnect the vehicle's battery to prevent short circuits and ensure accurate resistance readings.

2. 2

   Access the CAN Bus

   Locate an accessible point in the CAN bus network. The diagnostic port (OBD) is often easiest (CAN High on Pin 6, CAN Low on Pin 14), or access the wiring at the A004 control console connector.

3. 3

   Check termination resistance

   Set multimeter to resistance (Ω). With all modules connected, measure resistance between CAN High and CAN Low wires. A healthy network reads approximately 60 Ω. A reading of 120 Ω indicates a missing terminating resistor, broken wire, or a fault within a module. A reading near 0 Ω indicates a short circuit between the two wires.

4. 4

   Check for shorts to ground

   Measure resistance between the CAN High wire and a clean chassis ground, then repeat for the CAN Low wire. Both should read very high (MΩ or open circuit). A low reading indicates a short to ground in that specific wire.

5. 5

   Check CAN line voltages

   Reconnect the battery and turn the ignition on. Set multimeter to DC voltage. Measure between CAN High and chassis ground (should be 2.5V - 3.0V) and CAN Low and chassis ground (should be 2.0V - 2.5V). Incorrect voltages point to a short to power, short to ground, or a faulty transceiver in one of the control modules.

6. 6

   Isolate the fault

   If a wiring fault is suspected (e.g., 120 Ω reading or a short), isolate the problem by disconnecting modules one by one from the CAN network and re-testing. When the reading returns to normal, the disconnected module (likely the A004 operating console) or its wiring is the source.