Fendt 4.1.38 – Transmission Control / EST Module: Store forward transmission ratio' key on membrane keypad — Signal fault

The electrical signal from the 'Store forward transmission ratio' button on the tractor's membrane keypad is failing to reach the control unit, or the signal is out of the expected range, making the function unavailable.

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1. 1

   Inspect the membrane keypad on the armrest control console for physical damage, cracks, or signs of moisture ingress.

2. 2

   Check the wiring harness and connectors between the membrane keypad and the EST control module for loose pins, corrosion, or backed-out wires.

3. 3

   Use FENDIAS diagnostic software to monitor live inputs from the membrane keypad and verify if the EST module registers state changes when the key is pressed.

1. 1

   Power Down

   Turn off the tractor and disconnect the battery to prevent any electrical shorts during the repair.

2. 2

   Access the Keypad

   Remove the retaining screws and trim pieces on the armrest control console to access the underside of the membrane keypad.

3. 3

   Disconnect

   Carefully unplug the multi-pin electrical connector from the membrane keypad.

4. 4

   Clean and Test

   If corrosion is present on the harness side, clean it with electrical contact cleaner. If the harness is damaged, repair the wiring.

5. 5

   Replace Component

   If the wiring is good but the button has failed, remove the faulty membrane keypad control panel and install the new replacement unit.

6. 6

   Reassembly

   Reconnect the electrical harness, secure the keypad into the console, and reinstall all trim pieces.

7. 7

   Clear Codes

   Reconnect the battery and turn on the tractor. Use the tractor's terminal or the FENDIAS diagnostic tool to clear the stored fault code, then test the button to ensure the function has returned.