Fendt 01.1.7B – Multifunction Armrest (MFA) module (A039 or A100): Electrical fault with the cruise control buttons (MIN or MAX) on the joystick

Indicates an electrical fault with the cruise control buttons located on the joystick of the multifunction armrest. The Tractor Management System (TMS) is immediately switched off and disabled until the next time the engine starts.

• 922 Vario COM III
• 924 Vario COM III
• 927 Vario COM III
• 930 Vario COM III
• 933 Vario COM III
• 936 Vario COM III
• 300 Vario (COM III)
• 400 Vario (COM III)
• 700 Vario (COM III, SCR, S4)
• 800 Vario (COM III, SCR, S4)
• 900 Vario (COM III, SCR, S4)

1. 1

   Check the cruise control buttons (MIN/MAX) on the joystick for physical damage, sticking, or lack of tactile feedback.

2. 2

   Use the Fendt 160-pin adapter box to test the A039 / A100 MFA module inputs and outputs to verify if the signal fault is originating from the joystick switch itself or the MFA circuit board.

3. 3

   Check the internal wiring harness and connectors between the joystick/drive lever and the main MFA board for continuity or pin damage.

4. 4

   Ensure there are no underlying CAN bus communication faults (such as 00.0.03 or 00.0.04) that might be interrupting the MFA's ability to report to the basic control unit (A050).

1. 1

   Power Down

   Turn off the tractor and disconnect the battery power.

2. 2

   Remove the Joystick

   Carefully dismantle the multifunction armrest housing to access the base of the joystick/drive lever. Disconnect the wiring harness connecting the joystick to the MFA board.

3. 3

   Repair or Replace

   Option A (OEM Replacement): Install a brand-new Fendt joystick assembly. Option B (Remanufacture): Send the defective joystick to a specialized agricultural electronics repair center (such as Ilgenfritz Mechatronics). They can replace the defective microswitches, repair the internal circuit board, and stabilize the mechanical components.

4. 4

   Reinstallation

   Connect the new or repaired joystick to the MFA harness and reassemble the armrest.

5. 5

   Calibration

   Turn on the tractor. You may need to perform End of Line (EOL) programming or run transmission/joystick calibrations (e.g., calibration code 4003 for the travel range selector) via the Varioterminal to ensure the new lever is recognized and functioning correctly.