Massey Ferguson 0A.21.29 – Tractor Control Unit or Hydraulic ECU: External Hydraulic Valve 2 Issue

Malfunction associated with the second external hydraulic remote valve. Typically flagged as a 'Connection problem on a hydraulic valve' or an 'Issue With Spool Position Sensor Value'.

• 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

   Retrieve and Verify Codes: Use a compatible diagnostic tool or interface device to confirm code 0A.21.29 is active.

2. 2

   Inspect Connections: Physically inspect the wiring harness and the electrical connector at External Hydraulic Valve 2 for corrosion, backed-out pins, or wire chafing.

3. 3

   Check Sensor Values: Using the diagnostic tool, monitor the live data for the 'Spool Position Sensor Value' on Valve 2. Verify if the voltage is out of range (a typical healthy spool position sensor operates on a 5V supply and reads around 2.5V in neutral).

1. 1

   Disconnect Power

   Turn off the tractor and disconnect the battery before servicing electrical hydraulic components.

2. 2

   Clean and Re-seat Connector

   Disconnect the plug at External Hydraulic Valve 2. Clean the contacts with electrical contact cleaner, apply dielectric grease, and securely reconnect it.

3. 3

   Test Operation

   Reconnect the battery, clear the DTCs using the diagnostic tool, and operate the hydraulic valve to see if the code returns.

4. 4

   Replace Faulty Component

   If the code returns and the spool position sensor value remains erratic, the electric spool slice or its pilot pressure control unit is likely internally failed. Remove the hydraulic lines and mounting bolts to extract the faulty spool slice.

5. 5

   Install New Spool Slice

   Mount the replacement electric spool slice and torque the tie-rod bolts to manufacturer specifications. Reconnect the hydraulic lines and electrical harness.

6. 6

   Programming

   If replacing the entire Electric Spool Slice unit, the new module needs to be programmed to the tractor using a dealer-level diagnostic tool before it will function correctly.