Massey Ferguson 0A.21.21 – Mid Mount Valve Module or Tractor Control Unit (TCU): External Hydraulic Valve 2 Issue

Fault within the circuit of the second external hydraulic remote valve (spool valve). The underlying condition is typically a connection problem on the hydraulic valve, an electrical short/open circuit, or an implausible reading from the spool position sensor.

• 7724S
• 5712SL
• 7722
• 7722S
• 5713SL
• 7720S
• 7716
• 7718
• T4
• 7715
• 5710SL
• 7726
• 7726S
• 5711SL
• 7718S
• 7719
• 7714
• 7716S
• 7720
• Tier 4 (2015-2021)
• 7715S
• 7724
• 4707
• 4708
• 4709
• 4710
• 5608
• 5609
• 5610
• 5611
• 5612
• 5613
• 7614
• 7615
• 7616
• 7618
• 7619
• 7620
• 7622
• 7624
• 7626

1. 1

   Use a compatible diagnostic tool to retrieve the exact 0A.21.xx code to determine if the issue is a short to ground, open circuit, or mechanical bind.

2. 2

   Inspect the wiring harness leading to External Hydraulic Valve 2 for broken cables, corrosion in the connector pins, or a short circuit.

3. 3

   Check the spool position sensor for plausible values to ensure it is not returning a value outside the nominal range.

4. 4

   Verify proper CAN-bus communication between the Dash and the Mid Mount Valve Module.

1. 1

   Isolate the Valve

   Locate External Hydraulic Valve 2 (usually the second slice on the rear remote valve stack or mid-mount block).

2. 2

   Clean and Reseat Connectors

   Disconnect the electrical connector to the valve's solenoid and spool position sensor. Clean the contacts with electrical contact cleaner, apply dielectric grease, and reseat the connector.

3. 3

   Test the Solenoid/Sensor

   If the code persists, use a multimeter to check the resistance of the valve solenoid and the voltage sweep of the position sensor.

4. 4

   Replace Faulty Components

   If the sensor or solenoid fails the electrical test, replace the electronic control head or the spool valve assembly as dictated by the specific model's parts breakdown.

5. 5

   Clear Codes and Calibrate

   Reconnect the diagnostic tool, clear the 0A.21.21 fault code, and run a hydraulic valve calibration procedure (often required when a new spool valve or sensor is installed).