Case IH 4055 – UCM (Universal Control Module): Park Brake Valve (On / Off) Solenoid Supply Open Circuit

This code indicates that the control module has detected a break (open circuit) in the electrical circuit that supplies power to the parking brake solenoid valve. Because the circuit is open, the controller cannot actuate the solenoid to release or engage the parking brake properly.

• skid steer
• Skid Steer Loaders (SSL)
• Compact Track Loaders (CTL)
• Steiger
• Magnum
• Puma
• Farmall
• Case 695ST
• Wheel Loaders

1. 1

   Inspect the Solenoid Connector: Locate the park brake solenoid and disconnect the wiring harness. Check the pins for corrosion, moisture, or pushed-out terminals.

2. 2

   Test the Solenoid Coil: Using a multimeter, measure the resistance across the pins of the park brake solenoid coil. If the reading shows infinite resistance (OL), the coil itself is internally broken (open) and must be replaced.

3. 3

   Check the Wiring Harness: If the coil tests good, check the wiring harness between the solenoid connector and the UCM. Look for chafed, pinched, or broken wires. Perform a continuity test on the power and ground wires from the UCM to the solenoid plug.

4. 4

   Check Fuses/Relays: Verify that the fuses and relays supplying power to the UCM and the park brake circuit are intact.

1. 1

   Safety First

   Park the machine on a level surface, lower any attachments to the ground, turn off the engine, and remove the key. Chock the wheels or tracks since you will be working on the parking brake system.

2. 2

   Locate the Valve

   Locate the park brake solenoid valve. Depending on the machine, this is typically mounted on the transmission housing, the hydraulic control valve block, or near the hydrostatic drive pumps.

3. 3

   Disconnect and Isolate

   Unplug the electrical connector from the solenoid.

4. 4

   Repair the Circuit

   If the wiring is broken: Splice and repair the broken wire in the chassis harness using weather-sealed connectors, or replace the damaged harness section. If the solenoid is faulty: Clean the area around the valve to prevent dirt from entering the hydraulic system. Unbolt or unscrew the faulty solenoid coil/valve assembly from the hydraulic block.

5. 5

   Install New Parts

   Install the new solenoid coil or valve assembly. Torque to OEM specifications and reconnect the electrical plug.

6. 6

   Clear Codes and Test

   Turn the key to the ON position. Use the machine's diagnostic display or an electronic service tool (EST) to clear the inactive 4055 fault code. Start the machine and cycle the park brake switch to verify proper operation and ensure the code does not return.