Massey Ferguson A.50.20 – ECU or Autotronic 5: External Hydraulic Valve 5 Issue

The tractor's onboard diagnostic system has detected a malfunction in the circuit or operation of the 5th external hydraulic remote valve (spool valve). This is typically an electrical fault such as an open circuit, a short to ground, a short to power, or a signal out of range at the valve's solenoid.

• 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 the 5th external hydraulic valve at the rear remote stack and check the electrical connector at the solenoid for dirt, moisture, or corrosion.

2. 2

   Inspect the wiring harness leading to the 5th valve for rub points, pinched wires, or breaks that could cause an open circuit or short to ground.

3. 3

   Use a multimeter to test the solenoid coil resistance, verify ground integrity, and check for proper voltage reaching the connector when the valve is commanded from the cab.

4. 4

   Ensure the valve is not mechanically stuck or binding due to hydraulic fluid contamination, which can sometimes throw out-of-range position errors.

1. 1

   Safety Prep

   Park the tractor on a level surface, lower all hydraulic implements, turn off the engine, and relieve all hydraulic pressure by cycling the remote levers/buttons.

2. 2

   Clean the Area

   Thoroughly clean the rear hydraulic valve stack to prevent dirt from entering the hydraulic system during disassembly.

3. 3

   Address Electrical Faults

   If diagnostic tests revealed a failed solenoid coil (open or shorted), disconnect the wiring harness, remove the retaining nut on the end of the spool valve, and slide the old solenoid off. Install the new solenoid and torque the retaining nut to spec.

4. 4

   Address Mechanical/Seal Faults

   If the electrical circuit is intact but the valve is leaking or mechanically binding, the spool valve must be rebuilt or replaced. Remove the hydraulic lines connected to the 5th valve.

5. 5

   Valve Rebuild

   Unbolt the 5th valve section from the hydraulic stack. Disassemble the spool valve and inspect the internal bore for heavy scoring. If the bore is in good condition, rebuild the valve using an OEM spool valve repair kit (replacing all O-rings, seals, and springs).

6. 6

   Reassembly

   Reinstall the valve section into the stack, ensuring the mating O-rings between valve slices are properly seated. Reconnect hydraulic lines and the electrical harness.

7. 7

   Clear Codes

   Use a compatible Massey Ferguson diagnostic interface tool to clear the 0A.50.20 code from the ECU/Autotronic module.

8. 8

   Test

   Start the tractor, allow hydraulic pressure to build, and test the 5th remote valve for proper operation and leak-free performance.