Fendt 06.1.56 – A039 - MFA (Multifunction Armrest): Speed preselection button 540 pressed continuously for more than 30 seconds

The Speed preselection button 540 (for the rear PTO) on the multifunction armrest has been registered as pressed continuously for more than 30 seconds. This points to either a mechanical fault (jammed or stuck) or an electrical fault (short circuit). As a safety consequence, the system disables PTO speed preselection.

• 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) (Models 922, 924, 927, 930, 933, 936)

1. 1

   Examine the 540 PTO speed preselection button on the armrest console to see if it feels physically stuck, lacks its normal tactile click, or is jammed by dirt, spilled liquids, or debris.

2. 2

   Connect the FENDIAS diagnostic software and monitor the live input status of the A039 MFA module to see if the 540 button is actively reading as 'Closed/Pressed'.

3. 3

   If the button is not physically stuck, disassemble the armrest trim to access the switch contacts and use a multimeter to test the switch for a continuous short to ground or voltage.

4. 4

   Inspect the wiring harness and ribbon cables connecting the keypad to the main A039 MFA circuit board for chafing or pinched wires that could cause a short circuit.

1. 1

   Power Down

   Turn off the tractor ignition and disconnect the battery to prevent electrical damage during disassembly.

2. 2

   Clean the Switch

   If the button is physically sticking, use compressed air and a plastic-safe electrical contact cleaner around the edges of the 540 button to dissolve any sticky residue. Work the button up and down to free it.

3. 3

   Disassemble the Armrest

   If cleaning does not resolve the issue, remove the securing screws on the underside of the multifunction armrest to lift the top console cover.

4. 4

   Isolate the Keypad

   Disconnect the ribbon cable connecting the PTO keypad membrane to the A039 control board.

5. 5

   Replace the Faulty Component

   If the multimeter confirms the switch is internally shorted, replace the affected switch. Note: On many Fendt MFA units, the buttons are integrated into a sealed membrane keypad or a larger sub-module, meaning the specific keypad section must be replaced rather than a single button.

6. 6

   Reassembly

   Reconnect the keypad ribbon cables, secure the armrest cover, and reconnect the battery.

7. 7

   Clear Codes & Test

   Turn on the ignition. Use the tractor's terminal or FENDIAS to clear the stored 06.1.56 fault code. Test the 540 PTO button to ensure the speed preselects correctly and the code does not return.