Fendt 01.1.7E – A039 - MFA (Multifunction Armrest) / A100: A039 - MFA, multifunction armrest. Potentiometer, hand throttle. Electrical fault.

This code indicates an electrical failure, signal out of range, or communication loss regarding the hand throttle potentiometer (Component B035). The tractor's ECU cannot determine the position of the hand throttle, causing the Tractor Management System (TMS) to be automatically switched off until the next cold start, and the engine speed can only be controlled via the foot throttle.

• 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 series
• Fendt 300 Vario series
• Fendt 400 Vario series
• Fendt 500 Vario series
• Fendt 700 Vario series
• Fendt 800 Vario series
• Fendt 900 Vario series

1. 1

   Inspect the mechanical linkage between the hand throttle lever and the potentiometer to ensure plastic components are intact and the shaft is turning the sensor.

2. 2

   Check the wiring harness and connector (X183) at the potentiometer (B035) for continuity, short circuits, or corrosion.

3. 3

   Test the voltage supply to the sensor using a multimeter and breakout box (should read a steady 5V or 8-8.5V depending on generation).

4. 4

   Read the potentiometer signal using FENDIAS or a multimeter (expected: 16mA-22mA at idle, 2mA-8mA at full power). A signal < 2mA or > 22mA indicates a defective potentiometer.

1. 1

   Preparation

   Park the tractor on a level surface, apply the handbrake, turn off the ignition, and disconnect the battery.

2. 2

   Access the MFA

   Remove the retaining screws for the top cover/side console of the multifunction armrest to expose the internal circuit boards and controls.

3. 3

   Remove the Faulty Sensor

   Locate the hand throttle potentiometer (B035) mounted beneath the hand throttle lever. Disconnect its electrical connector.

4. 4

   Replacement

   Unbolt the potentiometer (or the integrated hand throttle lever assembly, depending on the specific part revision for your chassis) and install the new OEM replacement part.

5. 5

   Reassembly

   Reconnect the wiring harness and carefully reassemble the multifunction armrest console.

6. 6

   Clear Faults

   Reconnect the battery and turn on the ignition. Call up the fault memory on the instrument panel and clear the stored codes (often done by pressing the ESC button sequence or using FENDIAS).

7. 7

   Calibration

   The new potentiometer must be taught its minimum and maximum limits. Access the tractor's terminal calibration menu and enter Calibration Code 4002 (Hand throttle calibration). Follow the on-screen prompts to move the lever from idle to full throttle to save the new values.