Fendt 7.1.0A – A004 Control Console: A004 - "Active" key (only NA version) — Key / A004 signal fault

This fault code indicates a signal error or communication failure originating from the "Active" key located on the tractor's main control console. The system detects that the key's signal is either implausible, stuck, or failing to communicate over the CAN bus. When this code is active, the Front PTO (and in some configurations, the Rear PTO) cannot be engaged, and enhanced control functions may be restricted.

• 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 Farmer 400 Vario
• Fendt Favorit 700 / 900 Vario
• Fendt 300, 400, 700, 800, and 900 Vario series (including COM III generations)

1. 1

   Inspect the 'Active' key on the A004 control console to see if it is physically stuck, damaged, or jammed by dirt/debris.

2. 2

   Verify the voltage supply for the CAN bus by checking fuses F040 and F041 on fuse board A013.

3. 3

   Inspect the wiring harness and connectors between the A004 Control Console and the A002 Enhanced Control ECU for corrosion, loose pins, or wire chafing.

4. 4

   Test the switch's electrical continuity to determine if the contacts are permanently closed (shorted) or open.

1. 1

   Power Down

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

2. 2

   Clear Debris

   If the "Active" key is physically sticking, use electrical contact cleaner and compressed air to clear out any debris around the button housing.

3. 3

   Replace Fuses

   If fuses F040 or F041 on board A013 are blown, replace them and test the system. If they blow again immediately, there is a short in the console or harness.

4. 4

   Console Replacement/Repair

   If the key itself has failed internally or the A004 internal ECU is damaged (RAM/EEPROM failure), remove the right-hand mudguard panel to access and remove the A004 console. The unit must be sent to a specialized agricultural electronics repair shop or replaced with a new OEM unit.

5. 5

   EOL Programming

   If a new A004 Control Console is installed, you must use the FENDIAS diagnostic tool to perform EOL (End of Line) reprogramming so the new console can communicate properly with the tractor's CAN bus system.