Case IH 4371 – UCM (Universal Control Module): Reverse Pump Control Valves (Directional) Solenoid Left (B) Supply Open Circuit

The control module has detected an open circuit in the electrical supply line to the left-side reverse directional control solenoid on the hydrostatic drive pump, usually due to a broken wire, disconnected plug, or a burned-out solenoid coil.

• skid steer
• Skid Steer Loaders (SSL)
• Compact Track Loaders (CTL)
• SR Series
• SV Series
• TR Series
• TV Series
• SR175
• SV185
• TR270
• TR320

1. 1

   Locate the left reverse pump control valve on the hydrostatic drive pump assembly and inspect the wiring harness leading to the 'B' (Left) solenoid for obvious signs of damage, chafing, or rodent chewing.

2. 2

   Disconnect the electrical connector at the solenoid and check for loose, pushed-back, or corroded pins. Do the same at the UCM harness connector.

3. 3

   Using a digital multimeter, measure the resistance across the two pins of the left reverse solenoid. If the reading shows infinite resistance (OL), the internal coil is broken (open circuit) and the solenoid must be replaced.

4. 4

   If the solenoid tests good, check the continuity of the power and ground wires from the solenoid connector back to the UCM. An open line here indicates a wiring harness failure rather than a bad solenoid.

1. 1

   Preparation

   Park the machine on a level surface, lower the loader arms (or engage the lift cylinder lock), turn off the engine, and disconnect the negative battery cable.

2. 2

   Access the Pump

   Tilt the cab or open the rear/top access panels as required by your specific SSL/CTL model to gain access to the hydrostatic drive pumps.

3. 3

   Remove the Faulty Solenoid

   Disconnect the electrical harness from the left reverse directional solenoid. Clean the area around the valve to prevent dirt from entering the hydraulic system. Unscrew the retaining nut holding the solenoid coil to the valve stem. Slide the faulty solenoid coil off the valve cartridge.

4. 4

   Install the New Solenoid

   Slide the new OEM solenoid coil over the valve stem. Install and tighten the retaining nut to the manufacturer's torque specification (do not overtighten, as this can distort the valve).

5. 5

   Reassembly

   Reconnect the electrical harness, ensuring the locking tab clicks into place.

6. 6

   Testing

   Reconnect the battery, turn the key on, and use the Electronic Service Tool (EST) or the machine's display to clear the inactive 4371 fault code. Start the machine and test the ground drive in reverse to ensure proper operation and that the code does not return.