Massey Ferguson A.42.1A – Tractor Control Unit (TCU) / Hydraulic Control Unit: External Hydraulic Valve 4 Issue

Indicates an electrical or connection problem with the 4th rear hydraulic remote valve (spool valve). The system has detected a signal that is out of range, an open circuit, or a short to ground/power at the solenoid controlling this specific 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

   Locate External Hydraulic Valve 4 at the rear remote stack and inspect the solenoid connector for moisture, corrosion, or loose pins.

2. 2

   Trace the wiring harness back from the valve. Look for rub points, frayed wires, or pinched lines that could cause a short to ground or an open circuit.

3. 3

   Use a multimeter to measure the resistance across the pins of the valve's solenoid coil. Compare the reading to OEM specs to ensure the coil is not internally shorted or open.

4. 4

   Verify that the hydraulic valve block and the wiring harness have a solid, clean ground connection.

1. 1

   Depressurize the System

   Turn off the tractor engine. Cycle the hydraulic remote levers/buttons to relieve any residual hydraulic pressure in the system.

2. 2

   Access the Valve

   Locate the 4th external hydraulic spool valve at the rear of the tractor.

3. 3

   Disconnect Wiring

   Carefully unplug the electrical harness connector from the faulty solenoid.

4. 4

   Remove the Solenoid

   If the diagnostic tests proved the solenoid coil is dead, remove the retaining nut or bolt at the end of the spool valve stem and slide the old solenoid coil off.

5. 5

   Install New Parts

   Slide the replacement solenoid coil onto the valve stem and secure it with the retaining hardware. (If the mechanical spool valve itself is leaking or sticking, the entire valve section or seals may need to be replaced using a spool valve repair kit).

6. 6

   Reconnect and Clear Codes

   Reconnect the electrical harness. Turn the tractor on and use a compatible Massey Ferguson diagnostic interface tool to clear the 0A.42.1A DTC from the system.

7. 7

   Test

   Actuate the 4th hydraulic remote to ensure proper operation and verify the code does not return.