Fendt 18.2.40 – A050 - ECU, basic control unit: A050 - ECU, basic control unit

Warning message when attempting to fully activate — no BSAC connection. The tractor is attempting to fully activate the Auto-Guide / ISO bus steering system, but the main control unit cannot establish communication with the BSAC (Base Station Antenna Controller / GPS ECU).

• 922 Vario COM III
• 924 Vario COM III
• 927 Vario COM III
• 930 Vario COM III
• 933 Vario COM III
• 936 Vario COM III
• FENDT 300 Vario (COM III)
• FENDT 400 Vario (COM III)
• FENDT 700 Vario (COM III)
• FENDT 800 Vario (COM III)
• FENDT 900 Vario (COM III)
• Fendt 700-900 SCR series
• Fendt 900 Vario S4 series

1. 1

   Switch on the ignition and switch the Auto-Guide to standby mode to verify if the A058 Auto-Guide TopDock is energized (the LED on the standby switch should flash)

2. 2

   Check the CAN bus wiring harness and connectors between the A050 Basic Control Unit and the A058 Auto-Guide TopDock / BSAC receiver for breaks, corrosion, or loose pins

3. 3

   Ensure the GPS ECU (BSAC receiver) is securely attached to the TopDock, as it cannot be removed independently

4. 4

   Verify if the Auto-Guide software is up to date, as corrupted software can cause communication drops

1. 1

   Resolve Wiring Faults

   If physical damage is found in the harness between the A050 ECU and the TopDock, repair or replace the affected wiring sections.

2. 2

   Software Flash

   If the connection issue is software-related, extract the latest Auto-Guide firmware from AGCOnet to a predefined directory and program the tractor's Auto-Guide Terminal, GPS ECU, and steering valve block ECU.

3. 3

   Control Unit Replacement/Repair

   If the wiring is intact and software updates fail, the A050 Basic Control Unit or the TopDock receiver may have suffered an internal hardware failure. The A050 unit can often be sent to specialized agricultural electronics repair centers for board-level repair, or replaced.

4. 4

   Clear Fault Codes

   After the repair, clear the fault memory via the Instrument Panel (press buttons A, B, and C simultaneously) or using FENDIAS diagnostic software.

5. 5

   EOL Programming

   If the A050 Basic Control Unit is replaced with a new or refurbished unit, End-Of-Line (EOL) programming must be performed using FENDIAS to match the ECU to the tractor's specific configuration.