Massey Ferguson A.42.1F – Vehicle Control Unit (VCU) or Transmission/Hydraulic Controller: External Hydraulic Valve 4 Issue

Malfunction in the fourth rear remote auxiliary hydraulic spool valve circuit. The underlying condition is typically an electrical connection problem (such as a short, open circuit, or faulty solenoid) or a mechanical issue where the valve spool is sticking, jamming, or failing to actuate properly due to internal wear or debris.

• 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

   Verify the hydraulic fluid (UTTO) level and condition. Dirty oil or a blocked hydraulic/transmission filter can restrict flow and cause valve faults.

2. 2

   Inspect the wiring harness and connector leading to the External Hydraulic Valve 4 solenoid. Look for frayed wires, corrosion, or loose pins, which are common causes of electronic valve codes.

3. 3

   Connect a hydraulic hand pump to the valve port and pressurize it to 2500 psi. If the port cannot hold pressure, oil is leaking around the spool, indicating a damaged spool/bore, a failed centering spring, or internal contamination.

4. 4

   Check if the valve is physically sticking or jamming. Debris in the system can prevent the spool from returning to neutral.

1. 1

   Depressurize the System

   Shut off the tractor engine, engage the parking brake, and move the hydraulic control levers back and forth to relieve all residual pressure in the system.

2. 2

   Clean the Area

   Thoroughly clean the area around the rear remote valve block to prevent dirt from entering the hydraulic system during disassembly.

3. 3

   Disconnect Electricals

   Unplug the electrical harness connector from the Valve 4 solenoid.

4. 4

   Remove Hydraulic Lines

   Disconnect the hydraulic hoses/lines attached to the valve. Cap all open lines and ports immediately to prevent fluid loss and contamination.

5. 5

   Unbolt the Valve

   Remove the mounting bolts securing the Valve 4 section to the main hydraulic valve stack or base plate.

6. 6

   Inspect / Replace

   If rebuilding, disassemble the valve to inspect the spool and centering spring. Clean with solvent. If the bore is scored or the electronic solenoid has failed, the entire valve section must be replaced.

7. 7

   Reassembly

   Install the new valve section using new O-rings between the valve slices. Apply thread locker (e.g., Loctite 262) to fasteners if specified, and torque the mounting bolts to OEM specifications.

8. 8

   Reconnect and Bleed

   Reconnect the hydraulic lines and the electrical harness. Top off the hydraulic fluid with OEM-spec UTTO fluid. Start the tractor and cycle the valve several times to bleed air from the system.

9. 9

   Clear Codes

   Use a compatible diagnostic tool to clear the 0A.42.1F code from the system.