Fendt 4.1.35 – EST Control Module: "Store reverse transmission ratio" key on membrane keypad — Signal fault.

This code indicates that the electronic control unit is receiving an invalid, missing, or continuous (stuck) signal from the specific button on the side console's membrane keypad used to memorize the reverse transmission ratio. When this fault is active, the function is disabled and unavailable to the operator.

• 409 Vario
• 410 Vario
• 411 Vario
• 412 Vario
• 711 Vario
• 712 Vario
• 714 Vario
• 715 Vario
• 716 Vario
• 717 Vario
• 718 Vario
• 916 Vario
• 920 Vario
• 924 Vario
• 926 Vario
• 930 Vario
• Favorit 900 Vario series

1. 1

   Inspect the membrane keypad on the right-hand side console/armrest for tears, heavy wear, or a collapsed/stuck button dome over the 'Store reverse transmission ratio' key.

2. 2

   Determine if other keypad buttons are throwing similar signal faults (e.g., 4.1.34, 4.1.36). If multiple keys are failing, the entire Side Console (A004) may have an 8.5V supply failure, a CAN-bus communication issue, or an internal RAM/EEPROM failure.

3. 3

   Access the underside of the armrest console and inspect the wiring harness and connector plugging into the membrane keypad for loose pins, corrosion, or wire chafing.

4. 4

   Use the FENDIAS or SERDIA service diagnostics program to monitor live inputs from the side console. Press the button to see if the state changes in the software. If the state is stuck 'ON' or reads as an open circuit, the keypad is internally faulty.

1. 1

   Disconnect Power

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

2. 2

   Disassemble the Armrest/Console

   Remove the retaining screws holding the side console cover/bezel in place to access the electronic control modules.

3. 3

   Disconnect the Keypad

   Carefully unplug the ribbon cable or electrical connector linking the membrane keypad to the console's circuit board.

4. 4

   Remove the Old Keypad

   If using a membrane keypad repair sticker/overlay, use a heat gun on a low setting to gently warm the old membrane. Peel the defective membrane keypad off the plastic housing.

5. 5

   Clean the Surface

   Thoroughly clean the plastic mounting surface with isopropyl alcohol to remove all old adhesive residue. The surface must be completely smooth and dry.

6. 6

   Install the New Keypad

   Peel the backing off the new membrane keypad and carefully align it with the housing. Press it down firmly to ensure a good adhesive seal.

7. 7

   Reassembly

   Route the new ribbon cable through the housing slot and plug it securely into the circuit board connector. Reinstall the console covers and tighten the screws.

8. 8

   Test

   Reconnect the battery, turn on the ignition, and clear the stored fault codes using the FENDIAS tool. Test the "Store reverse transmission ratio" button to ensure the function is restored and the fault code does not return.