Fendt A.1.22 – Tractor ECU / Hydraulic Control Module: Spool valve fault, valve 2

The supply voltage in the valve has dropped below 8 volts, forcing the auxiliary control valve to automatically move into the neutral position.

• 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 series
• Fendt Favorit 700 Vario series
• Fendt Favorit 900 Vario series
• Fendt 900 Vario series (916, 920, 924, 926, 930)

1. 1

   Use a multimeter to measure the supply voltage directly at the electrical connector for Spool Valve 2 (Y016) while the tractor is keyed on. Verify if the voltage is actually below 8V.

2. 2

   Trace the wiring harness from the valve back to the ECU. Look for chafed wires, pinched lines, or melted insulation that could be causing a high-resistance short to ground.

3. 3

   Disconnect the Y016 valve and inspect the pins for water ingress, bent pins, or green corrosion, which commonly causes voltage drops in agricultural environments.

4. 4

   Verify the tractor's overall battery and alternator voltage to ensure the low voltage isn't a symptom of a failing charging system.

5. 5

   Test the resistance of the valve's solenoid/actuator. An internal failure in the actuator can draw excessive current, pulling the reference voltage down below the 8-volt threshold.

1. 1

   Power Down

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

2. 2

   Locate the Valve

   Locate the rear hydraulic valve stack. Identify Spool Valve 2 (Y016).

3. 3

   Clean and Repair Wiring

   If the diagnostic checks revealed corrosion at the connector, clean the pins thoroughly with contact cleaner and apply dielectric grease. If the wiring harness is damaged, cut out the damaged section and solder/heat-shrink a new wire segment.

4. 4

   Replace the Actuator/Valve

   If the wiring is sound and the voltage at the connector is correct when unplugged (but drops when plugged in), the valve actuator has failed internally. Unbolt the electronic actuator head from the spool valve slice (or replace the entire spool valve slice depending on the specific Bosch Rexroth block design on your model) and install the replacement.

5. 5

   Reassemble and Clear Codes

   Reconnect the electrical harness and the battery. Turn on the tractor and use the Fendt terminal or the FENDIAS diagnostic software to clear the A.1.22 fault code.

6. 6

   Functional Test

   Actuate Spool Valve 2 manually and via the joystick to ensure it reaches full flow without defaulting to neutral.