Massey Ferguson A.21.27 – Hydraulic Control Module / Mid Mount Valve Module: External Hydraulic Valve 2 Issue

Failure or communication error involving the secondary auxiliary remote spool valve (External Hydraulic Valve 2) located at the rear of the tractor. The issue is typically caused by a failure of the spool position sensor, a loss of communication between the dash and the valve module, or internal/external fluid leaks causing a pressure drop in the Bosch Rexroth SB23 valve block.

• 5710SL
• 5711SL
• 5712SL
• 5713SL
• T4
• 5608
• 5609
• 5610
• 5611
• 5612
• 5613
• 7614
• 7615
• 7616
• 7618
• 7619
• 7620
• 7622
• 7624
• 7626
• 5400 Series
• 6200 Series
• 6400 Series
• 7400 Series
• 8200 Series
• 8400 Series

1. 1

   Verify the UTTO (Universal Tractor Transmission Oil) hydraulic fluid level and condition. Dark, burnt, or milky fluid can cause valve sticking.

2. 2

   Inspect the Bosch SB23 valve block at the rear of the tractor for external leaks, which are highly common and lead to pressure loss.

3. 3

   Check the wiring harness for the spool position sensor and verify communication between the dash and the mid-mount valve module.

4. 4

   Determine if the valve is failing to actuate due to a dead electronic control unit (ECU on the valve) or if it is a mechanical seal failure.

1. 1

   Clean valve area

   If the issue is a mechanical leak: Clean the rear remote valve area thoroughly to prevent contamination.

2. 2

   Relieve pressure

   Relieve all hydraulic system pressure.

3. 3

   Use reseal kit

   Instead of replacing the entire valve, use a specialized Spool Valve Replacement/Reseal Kit (e.g., K-Line AT20010).

4. 4

   Replace seals

   Remove the valve spool, replace the internal O-rings and seals provided in the kit, and reassemble.

5. 5

   Bleed system

   Bleed the hydraulic system carefully, as aerated fluid can cause spontaneous cylinder action and vibrations.

6. 6

   Replace ECU

   If the issue is an electronic failure (Valve ECU): Replace the specific Bosch EHR control unit.

7. 7

   Convert to joystick control

   Alternatively, perform a conversion that removes the unreliable CAN Bus/ECU technology from the valve entirely, replacing it with a direct electrical joystick control wired to the valve solenoids.