Fendt 4.1.FF – Transmission e-box / EST (A001 or A002): Transmission e-box — Internal fault (RAM / EEPROM) / Error in transmission EST control unit

The tractor will experience a loss of standard transmission control, but continuation in emergency mode (auxiliary operation) is possible.

• 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
• Fendt Farmer 400 Vario series (409, 410, 411, 412)
• Fendt Favorit 700 Vario series (711, 712, 714, 716)
• Fendt 800 Vario series (815, 817, 818)
• Fendt Favorit 900 Vario series (916, 920, 924, 926, 928, 930)
• Fendt 300, 400, 700, 800, and 900 Vario (COM III) generations

1. 1

   Verify that the tractor can still drive using the emergency/auxiliary operation mode

2. 2

   Check the voltage supply for the CAN-Bus on fuse board A013, specifically inspecting fuses F040 and F041

3. 3

   Turn the ignition off and listen closely to the transmission e-box; the release of the relay must be audible. If it does not release, the relay or wiring may be sticking

4. 4

   Test the plug connections to the transmission actuator unit and the EST module to ensure there is no corrosion or loose pins causing data transfer interruptions

1. 1

   Attempt EOL Programming

   If the EEPROM has simply corrupted (sometimes throwing a checksum error alongside the internal fault), connect the FENDIAS diagnostic tool and attempt to run a new EOL (End of Line) programming sequence.

2. 2

   Replace the EST Unit

   If EOL programming fails or the RAM is physically damaged, the Transmission e-box (A001/A002) must be replaced.

3. 3

   Install the New Module

   Disconnect the battery, remove the faulty EST main unit, and plug in the replacement module.

4. 4

   Calibrate the System

   After installing a new transmission e-box, you must use the FENDIAS system to perform EOL programming and run the transmission calibration codes (e.g., calibration code 4007 for transmission ratio and code 4003 for travel range detection) to sync the new module with the tractor's actuator unit and sensors.