Case IH 4071 – UCM (Universal Control Module): Forward Pump Control Valves (Directional) Solenoid Left (B) Supply Open Circuit

The control module has detected a break in the electrical circuit supplying power to the left-side forward directional solenoid on the hydrostatic drive pump. Because the circuit is open, electrical current cannot flow, meaning the solenoid cannot actuate. This typically results in a loss of left-side forward drive or a complete ground drive lockout for safety.

• skid steer
• Skid Steer Loaders (SR130, SR160, SR175, SV250)
• Compact Track Loaders (TR270, TR320)
• Tractors

1. 1

   Visually inspect the wiring harness leading to the Left (B) Forward Pump Control Solenoid for obvious breaks, rodent damage, or chafing against the chassis.

2. 2

   Unplug the connector at the left solenoid and check for water intrusion, severe corrosion, or pins pushed back into the plastic housing.

3. 3

   Perform a coil resistance test using a digital multimeter across the two pins of the solenoid coil. An infinite (OL) reading indicates a broken internal coil, while normal resistance points to a wiring fault.

4. 4

   Perform a harness continuity test on the supply wire between the UCM and the solenoid. An infinite reading confirms a broken wire in the harness.

1. 1

   Disconnect battery (If wiring is broken)

   Disconnect the machine's battery.

2. 2

   Trace open wire

   Trace the open wire to the point of the break.

3. 3

   Splice wire

   Cut out the damaged section and splice in a new section of wire using marine-grade, heat-shrink butt connectors to prevent future moisture intrusion.

4. 4

   Secure harness

   Secure the harness with zip ties away from moving parts or high-heat areas.

5. 5

   Disconnect battery and depressurize (If solenoid coil is faulty)

   Disconnect the battery and ensure the hydraulic system is depressurized.

6. 6

   Unplug connector

   Unplug the electrical connector from the Left (B) Forward Pump Control Solenoid.

7. 7

   Remove retaining nut

   Remove the retaining nut at the end of the solenoid valve stem.

8. 8

   Remove faulty coil

   Slide the faulty electromagnetic coil off the valve cartridge (you usually do not need to open the hydraulic system or remove the cartridge valve itself just to replace the coil).

9. 9

   Install new coil

   Slide the new solenoid coil onto the stem and secure it with the retaining nut (do not overtighten, or you may distort the cartridge).

10. 10

    Reconnect connector

    Plug the electrical connector back in.

11. 11

    Test and clear codes

    Reconnect the battery, clear the UCM fault codes using a diagnostic tool, and test the ground drive functions.