Case IH 519014-05 - UCM – UCM: Current Below Normal or Open Circuit

The system has detected that the electrical current flowing to the front suspension lock solenoid valve is lower than the required operational threshold. This typically means there is an open circuit, a disconnected wire, a blown fuse, or a completely failed (open) solenoid coil. When this occurs, the front suspension automatic damping may be deactivated, and the suspension will default to a locked or rigid state.

• MAGNUM AFS Connect
• Puma Series (e.g., 150, 165, 175, 180, 260 CVT)
• Maxxum Series
• Magnum Series (e.g., 340)

1. 1

   Check Fuses: Verify the fuses supplying power to the front suspension system (often labeled as 12VM or 12VF3 supply voltage). A blown fuse will cut power to the circuit, resulting in a low current/open circuit code.

2. 2

   Inspect Wiring and Connectors: Trace the wiring harness from the UCM to the front suspension lock solenoid. Look for disconnected plugs, chafed wires, or broken lines.

3. 3

   Test the Solenoid Coil: Disconnect the solenoid and use a multimeter to measure the resistance across the coil pins. If the reading shows infinite resistance (OL), the coil is internally broken (open) and must be replaced.

4. 4

   Check for Corrosion: Inspect the electrical connector at the solenoid for water intrusion, dirt, or green corrosion, which can cause high resistance and trigger an open circuit fault.

1. 1

   Safety First

   Park the tractor on a level surface, turn off the engine, and engage the parking brake. Ensure the front suspension is fully lowered or mechanically supported to relieve any residual hydraulic pressure.

2. 2

   Locate the Solenoid

   Locate the front suspension control valve block (usually mounted near the front axle). Identify the specific lock solenoid valve.

3. 3

   Disconnect Power

   Unplug the electrical wiring harness connector from the faulty solenoid.

4. 4

   Remove the Coil

   Remove the retaining nut at the top of the solenoid valve stem. Slide the faulty electromagnetic coil off the valve cartridge. (Note: You usually do not need to remove the hydraulic valve cartridge itself, which prevents fluid loss).

5. 5

   Install the New Coil

   Slide the replacement solenoid coil over the valve stem and secure it with the retaining nut. Do not overtighten.

6. 6

   Reconnect and Test

   Plug the electrical connector back in. Turn on the tractor, clear the UCM fault codes via the armrest display or diagnostic tool, and test the front suspension lock/auto modes to ensure the code does not return.