Massey Ferguson A.3X.28 – Vehicle Control Unit (VCU) or Auxiliary Hydraulic Control Module: External Hydraulic Valve 3 Issue

Indicates a malfunction, electrical connection problem, or performance restriction associated with the 3rd rear auxiliary/remote hydraulic spool valve.

• 5710SL
• 5711SL
• 5712SL
• 5713SL
• T4
• 4707
• 4708
• 4709
• 4710
• 5608
• 5609
• 5610
• 5611
• 5612
• 5613
• 7614
• 7615
• 7616
• 7618
• 7619
• 7620
• 7622
• 7624
• 7626
• 7714
• 7715
• 7715S
• 7716
• 7716S
• 7718
• 7718S
• 7719
• 7720
• 7720S
• 7722
• 7722S
• 7724
• 7724S
• 7726
• 7726S

1. 1

   Check the hydraulic fluid (UTTO) level and condition. Look for contaminated or dirty oil.

2. 2

   Inspect the hydraulic/transmission filter for blockages, which can restrict flow and trigger valve faults.

3. 3

   Inspect the wiring harness and electrical connector going to External Valve 3. Look for damaged wires, corrosion, or loose connections that would cause a communication drop to the solenoid.

4. 4

   Inspect the rear hydraulic couplers for damage, blockages, or worn hoses that might be causing a pressure-related fault.

5. 5

   Determine if the spool valve is physically sticking or if the issue is purely electrical. A dead hydraulic response often points to a stuck valve or a failed solenoid.

1. 1

   Relieve Pressure

   Park the tractor on a level surface, lower all implements to the ground, turn off the engine, and cycle the hydraulic controls to relieve all internal system pressure.

2. 2

   Access the Valve Stack

   Locate the rear external hydraulic valve block (spool valve assembly) at the rear of the tractor. Identify Valve 3.

3. 3

   Disconnect Electricals

   Unplug the electrical wiring harness from the Valve 3 solenoid.

4. 4

   Remove Hydraulic Lines

   Disconnect the hydraulic hoses/lines connected to the valve. Cap all open lines and ports immediately to prevent dirt from entering the hydraulic system.

5. 5

   Unbolt the Valve

   Remove the mounting bolts securing the spool valve to the valve stack or lift cover.

6. 6

   Replace or Rebuild

   Install the new replacement spool valve assembly (or replace the faulty solenoid/seals if rebuilding). Ensure all O-rings between the valve slices are seated correctly.

7. 7

   Reassembly

   Bolt the valve back into place, torque to OEM specifications, and reconnect the hydraulic lines and electrical harness.

8. 8

   Fluid Top-Up and Bleed

   Top up the hydraulic fluid (UTTO) to replace any lost during the repair. Start the tractor and operate Valve 3 several times to bleed air from the system.

9. 9

   Clear Codes

   Use a compatible diagnostic tool to clear the A.3X.28 DTC from the tractor's memory. Check for leaks around the new valve.