Massey Ferguson 13.00.0C – TRANS1: Hydraulic Trailer Brake Solenoid Issue Dyna VT

The transmission controller has detected an electrical fault (such as an open circuit, short to +12V, short to ground, or abnormal amp draw) or a functional anomaly in the solenoid responsible for actuating the hydraulic trailer brakes.

• 7714
• 7715
• 7715S
• 7716
• 7716S
• 7718
• 7718S
• 7719
• 7720
• 7720S
• 7722
• 7722S
• 7724
• 7724S
• 7726
• 7726S
• Tier 4 (2015-2021)
• 6614
• 6615
• 6616
• 7614
• 7615
• 7616
• 7618
• 7619
• 7620
• 7622
• 7624
• 7626
• 8S.205
• 8S.225
• 8S.245
• 8S.265

1. 1

   Check the main fuse box for the specific fuse assigned to the trailer brake solenoid (often a 7.5A or 10A fuse)

2. 2

   Inspect the wiring harness leading to the hydraulic trailer brake valve block for chafed wires, melted insulation, or debris that could cause a short circuit to the chassis or an open circuit

3. 3

   Disconnect the plug at the solenoid and use a multimeter to check for proper voltage from the TRANS1 controller when the brakes are applied

4. 4

   Measure the resistance across the pins of the solenoid coil to check for an internal failure (infinite resistance/open or zero resistance/shorted)

5. 5

   Check the transmission/hydraulic oil level and ensure it is free of heavy contamination that could jam the mechanical spool valve the solenoid operates.

1. 1

   Preparation

   Park the tractor on a flat, level surface, engage the parking brake, and turn off the engine. Relieve any residual hydraulic pressure by pumping the brake pedals a few times.

2. 2

   Locate the Valve

   Locate the hydraulic trailer brake valve assembly. On Dyna VT models, this is typically mounted on the rear transmission housing or accessed through a side panel on the back end.

3. 3

   Clean the Area

   Thoroughly clean the area around the valve block with brake cleaner to prevent dirt from entering the hydrostatic loop during removal.

4. 4

   Disconnect Electricals

   Unplug the electrical harness connector from the trailer brake solenoid.

5. 5

   Catch Fluid

   Place a drain pan underneath the valve block to catch residual transmission/hydraulic oil.

6. 6

   Remove the Solenoid/Valve

   Depending on the exact failure and model, you may be able to unbolt just the solenoid coil. If the entire valve is being replaced, loosen the retaining bolts (usually hex heads) and carefully pull the valve assembly away from the transmission housing.

7. 7

   Replace O-Rings

   Remove the old O-rings. Never reuse old O-rings. Lubricate the new O-rings with clean transmission oil and fit them to the new valve/solenoid. Note: Do not move or adjust the thrust collars on the valve spools during installation.

8. 8

   Installation

   Insert the new solenoid/valve assembly into the housing. Torque the mounting bolts to OEM specifications (refer to your specific model's torque chart, often around 25-30 Nm for hydraulic block bolts).

9. 9

   Reassembly

   Reconnect the electrical harness.

10. 10

    Fluid and Testing

    Top up the transmission oil at the external filling station if a significant amount was lost. Start the tractor, test the trailer brake function, check for leaks, and use a diagnostic tool to clear the 13.00.0C fault code from the TRANS1 module.