Fendt B.1.22 – A002 / A008: CAN Bus communication fault between the A008 Terminal and the Teach-in (program run)

The Variotronic TI (Tractor Management System "Teach-in" function) will not function or is completely non-operational.

• 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
• 411 Vario COM III
• 412 Vario COM III
• 413 Vario COM III
• 414 Vario COM III
• 415 Vario COM III
• 712 Vario COM III
• 714 Vario COM III
• 716 Vario COM III
• 718 Vario COM III
• 818 Vario COM III
• 820 Vario COM III
• FENDT 300 Vario (COM III)
• FENDT 400 Vario (COM III) (e.g., 409, 410, 411, 412)
• FENDT 700 Vario (COM III) (e.g., 711, 712, 714, 715, 716, 717)
• FENDT 800 Vario (COM III) (e.g., 815, 817, 818)
• FENDT 900 Vario (COM III) (e.g., 916, 920, 924, 926, 930)

1. 1

   Review Fendt workshop manual Chapter 9700, Reg. A - Principle of Variotronic TI operation to understand the expected data flow

2. 2

   Consult Wiring Diagram Sheet 22 / 6 and test the CAN bus lines between the A008 Terminal and the A002 Enhanced Control ECU for continuity, shorts to ground, or shorts to power

3. 3

   Inspect the physical pins and connectors at both the A008 Terminal and the A002 ECU for corrosion, backed-out pins, or moisture ingress

1. 1

   Disconnect Battery

   Always disconnect the tractor's battery before unplugging ECUs to prevent voltage spikes.

2. 2

   Repair Wiring

   If the diagnostic checks reveal a break or high resistance in the CAN bus wiring between A002 and A008, repair or replace the affected harness section according to Wiring Diagram Sheet 22 / 6.

3. 3

   Module Replacement

   If the wiring harness is intact and passes all load tests, the fault lies internally within either the A008 Terminal or the A002 ECU. Swap the terminal with a known-good unit (if available) to isolate the failure.

4. 4

   Reprogramming

   If the A002 ECU or A008 Terminal is replaced, the new module will likely require EOL (End of Line) programming via FENDIAS (Fendt's diagnostic software) to pair it with the tractor's CAN network.

5. 5

   Clear Codes

   Reconnect the battery, turn the ignition on, and use the terminal or FENDIAS to clear the stored B.1.22 fault code. Test the Variotronic TI system to ensure the Teach-in function is operational.