Fendt 01.1.9A – A039 / A100 Multifunction Armrest (MFA): A039 - MFA, multifunction armrest. Communication fault with cruise control button MIN. TMS is switched off. CAN bus.

CAN bus communication failure specifically isolated to the "MIN" cruise control button located on the Vario joystick. As a safety consequence, the Tractor Management System (TMS) is automatically disabled and will not function until the fault is resolved or the engine is restarted.

• 922 Vario COM III
• 924 Vario COM III
• 927 Vario COM III
• 930 Vario COM III
• 933 Vario COM III
• 936 Vario COM III
• 311
• 312
• 409
• 410
• 411
• 412
• 711
• 712
• 714
• 715
• 716
• 717
• 815
• 817
• 818
• 916
• 920
• 922
• 924
• 926
• 927
• 930
• 933
• 936

1. 1

   Check for related active codes (such as 01.1.9B for MAX button or 01.1.9C for TMS button) to determine if multiple joystick buttons are failing simultaneously, which indicates a broader CAN bus failure, disconnected harness, or total joystick failure rather than a single bad button.

2. 2

   Inspect the cruise control MIN button on the Vario joystick for physical damage, sticking, or debris preventing proper contact.

3. 3

   Test the A039 multifunction armrest using a 160-pin adapter box to verify voltage supply and CAN bus continuity.

1. 1

   Power down the tractor and disconnect the battery to prevent electrical shorts on the CAN bus.

2. 2

   Access the A039 / A100 Multifunction Armrest assembly.

3. 3

   Carefully disassemble the Vario joystick handle to access the internal button contacts.

4. 4

   Clean the contacts for the cruise control MIN button. If the button microswitch or the joystick's internal circuit board is damaged, replace the faulty button using a joystick repair kit. If the internal board is unserviceable, the entire Vario joystick/MFA unit must be replaced.

5. 5

   Reassemble the joystick and armrest housing.

6. 6

   Reconnect the battery and turn the ignition on.

7. 7

   Clear the stored fault codes via the tractor's terminal.

8. 8

   Test the cruise control MIN button and verify that the Tractor Management System (TMS) engages without switching off.