Fendt A.1.FB – Enhanced Control ECU (A002 E-box): S068 - Switch (external), valve actuation, lower. Button faulty, signal line faulty.

The external push button located on the rear fender, used to lower the rear hydraulic spool valve/power lift, is sending an incorrect signal. The system detects either a mechanical failure within the button (e.g., stuck or internally shorted) or a fault in the signal wiring (break or short circuit). The external valve actuation is disabled for safety.

• 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
• 413 Vario
• 414 Vario
• 415 Vario
• 815 Vario
• 817 Vario
• 818 Vario
• 819 Vario
• 820 Vario
• 918 Vario
• 922 Vario
• 927 Vario
• 933 Vario
• 936 Vario

1. 1

   Measure Signal Voltage: Check the signal voltage at pin 2 and pin 1 of the S068 switch connector with the ignition ON.

2. 2

   Switch Open (Not Actuated): Resistance (R) should be infinite. Signal voltage should read 6.1 V DC (or 8.0 V DC depending on the specific A002/A050 controller version).

3. 3

   Switch Closed (Actuated): Resistance (R) should be approximately 0 ohms. Signal voltage should drop to 0 V DC.

4. 4

   Wiring Inspection: If the voltage readings at the connector are missing entirely, trace the wiring harness back to the ECU to check for breaks, chafing, or a short circuit to earth.

1. 1

   Disconnect battery

   Turn off the tractor, remove the key, and disconnect the negative battery terminal to prevent electrical spikes.

2. 2

   Locate button

   Locate the S068 external lower valve actuation button on the rear fender.

3. 3

   Inspect button

   Inspect the button for physical damage, dirt ingress, or a stuck mechanism (a common cause for the 'double actuation' or stuck signal fault).

4. 4

   Disconnect switch plug

   Disconnect the AMP Superseal plug connection at the back of the switch.

5. 5

   Perform diagnostic checks

   Perform the diagnostic voltage and resistance checks outlined above.

6. 6

   Replace faulty switch

   If the wiring is intact but the switch fails the resistance test, pop the faulty switch out of the fender housing and install the replacement button.

7. 7

   Reconnect wiring and battery

   Reconnect the wiring harness and the battery.

8. 8

   Clear fault codes and restart

   Clear the stored fault codes. The system locks out the button when a fault is detected; it will remain inoperable until you perform a complete, trouble-free cold start of the tractor.