Fendt 7.1.AA – A004 - ECU, control panel: Communication fault with the Active key

The system is detecting a loss of communication or a signal fault from the 'Active' button, which prevents the front PTO from being engaged normally. This specifically affects the Comfort/Enhanced Control Front PTO system.

• 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
• Farmer 400
• Favorit 700
• Favorit 900
• 300/400/700/800/900 Vario (COM III) series

1. 1

   Inspect the 'Active' key on the A004 control panel for mechanical binding or sticking

2. 2

   Check the CAN-Bus power supply voltage at the A013 printed circuit/fuse board, specifically inspecting fuses F040 and F041

3. 3

   Consult the PTO circuit diagram (Sheet 32) to test the signal lines and CAN-Bus communication harness between the A004 control panel and the main E-box

1. 1

   Inspect and replace fuses

   Turn off the tractor and locate the A013 fuse board. Inspect and replace fuses F040 or F041 if blown, as this will drop CAN communication to the console.

2. 2

   Clean the 'Active' key

   Inspect the A004 control console. Clean the area around the 'Active' key to ensure debris is not causing the button contacts to stick internally.

3. 3

   Check wiring continuity

   Using a multimeter, check the continuity of the CAN-Bus wiring harness from the A004 control panel to the single e-box to rule out an open or shorted wire.

4. 4

   Diagnose A004 control panel

   If the wiring and fuses are intact but the communication fault persists, the internal circuitry of the A004 control panel has failed.

5. 5

   Replace or repair A004 control panel

   Remove the faulty A004 control panel and install a replacement unit (or send the unit to a specialized agricultural electronics repair center, as these boards are frequently repaired rather than replaced).

6. 6

   Clear code and test

   Reconnect the battery, turn on the ignition, and use the FENDIAS diagnostic tool to clear the 7.1.AA code. Test the Front PTO engagement to verify the repair.