Case IH 155 – TRANS (Transmission Controller): Front Suspension Lock Valve is stuck off (suspension will not unlock)

This code indicates a malfunction in the front axle suspension system where the lock valve (or blocking valve) is mechanically or hydraulically stuck in the 'Off' (locked) position. As a result, the system is unable to unlock the suspension, leading to a rigid front axle.

• MX Magnum
• 215
• 225
• 235
• 245
• 250
• 275
• 280
• 305
• 310
• 335
• 340
• Puma 115
• Puma 125
• Puma 140
• Puma 155
• Puma 160
• MXM120
• MXM130
• MXM140
• MXM155
• MXM175
• MXM190

1. 1

   Check for related electrical codes such as 10015 (Front suspension Lock Valve Solenoid is open circuit or is shorted to ground) or 10021 (Front Suspension lock out Solenoid over current).

2. 2

   Inspect the wiring harness leading to the front suspension control manifold for rubbed wires, corrosion in the connector, or a poor ground.

3. 3

   Use a multimeter to check the resistance of the suspension lock valve solenoid coil to see if it is open (infinite resistance) or shorted.

4. 4

   Verify the transmission controller is sending 12V to the solenoid when an 'unlock' command is requested.

1. 1

   Secure the Machine

   Park the tractor on a hard, level surface. Safely support the front chassis with heavy-duty jack stands to remove the weight and load from the front axle suspension cylinders.

2. 2

   Relieve Hydraulic Pressure

   Turn off the engine and cycle the steering and hydraulic remotes to relieve residual hydraulic pressure.

3. 3

   Locate the Valve

   Locate the front suspension hydraulic manifold block. Identify the specific lock/blocking valve cartridge (refer to your specific model's hydraulic schematic).

4. 4

   Remove the Solenoid

   Disconnect the electrical harness from the lock valve solenoid. Remove the retaining nut at the end of the stem and slide the electromagnetic coil off the valve cartridge.

5. 5

   Extract the Valve Cartridge

   Using the appropriate wrench, carefully unthread the lock valve cartridge from the manifold block. Have a catch pan ready for hydraulic fluid.

6. 6

   Inspect and Clean

   Inspect the cartridge for damaged O-rings, broken backup rings, or metal debris holding the internal spool open. While sometimes they can be cleaned with brake cleaner and compressed air, a stuck valve usually requires replacement.

7. 7

   Install the New Valve

   Lubricate the O-rings on the new valve cartridge with clean hydraulic oil. Thread it into the manifold and tighten to the OEM torque specification.

8. 8

   Reassemble

   Slide the solenoid coil back over the new cartridge stem, install the retaining nut, and reconnect the electrical harness.

9. 9

   Test and Clear Codes

   Start the tractor, allow hydraulic pressure to build, and test the suspension lock/unlock function. Use an Electronic Service Tool (EST) to clear the TRANS 155 fault code from the Transmission Controller.