Fendt 01.1.7A – A039 MFA (Multifunction Armrest): A039 - MFA, multifunction armrest Cruise control button MAX (on joystick)

There is an electrical fault (open circuit, short circuit, or failed switch contact) in the cruise control button located on the Vario drive lever/joystick, causing the TMS (Tractor Management System) to switch off.

• 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 200 Vario (V/F/P)
• Fendt 300 Vario
• Fendt 400 Vario (409, 410, 411, 412, 415)
• Fendt 700 Vario (711, 712, 714, 716, 718)
• Fendt 800 Vario (815, 817, 818, 820)
• Fendt 900 Vario (916, 920, 924, 926, 930, 933, 936)

1. 1

   Check for related CAN communication fault codes (e.g., 01.1.9A or 01.1.9B) to rule out CAN bus wiring issues to the armrest

2. 2

   Inspect the internal wiring harness and connector linking the Vario joystick to the A039 multifunction armrest control board for chafing, pinched wires, or loose pins

3. 3

   Test the cruise control MAX button with a multimeter for proper continuity when pressed and released

4. 4

   Inspect the membrane keypad and the physical plastic button on the joystick for wear, sticking, or liquid ingress

1. 1

   Power Down

   Turn off the tractor and disconnect the battery to prevent short circuits while working on the armrest electronics.

2. 2

   Disassemble the Joystick

   Carefully remove the joystick cover/housing on the multifunction armrest to expose the internal switches and circuit board.

3. 3

   Component Replacement

   If the fault is isolated to a broken physical button or a damaged membrane keypad, replace them using aftermarket repair kits. If the internal microswitch or the joystick's internal circuit board has failed, replace the entire Vario joystick assembly.

4. 4

   Reassembly

   Install the new switch or joystick assembly, ensuring the wiring harness is routed correctly so it does not pinch when the joystick is moved.

5. 5

   Clear Codes and Test

   Reconnect the battery, turn on the ignition, and use the terminal to clear the stored fault codes. Start the tractor and verify that the TMS can now be successfully engaged.