Case IH 4072 – UCM (Universal Control Module): Forward Pump Control Valves (Directional) Solenoid Left (B) Supply Shorted To Ground

The electrical supply circuit providing power to the left-side forward directional solenoid on the hydrostatic drive pump has a short to ground. The control module has detected that the voltage intended to actuate the solenoid is finding an unintended path to the chassis/ground. This condition will typically disable the left-side forward drive, as the valve cannot be electronically actuated to stroke the pump.

• skid steer
• Skid Steer Loaders (SSL)
• Compact Track Loaders (CTL)
• SR130
• SR150
• SR175
• SV185
• SR200
• SR220
• SR250
• SV250
• SV300
• TR270
• TR320
• TV380

1. 1

   Inspect the wiring harness routing from the UCM to the hydrostatic pump control valves for chafed wire insulation, pinched wires, or melted loom

2. 2

   Disconnect the electrical connector at the Left (B) Forward Pump Control Solenoid to isolate it

3. 3

   Using a digital multimeter, measure the resistance between the solenoid's supply pin and its metal housing to check for an internal short to ground

4. 4

   With the solenoid and the UCM disconnected, test the supply wire in the harness for continuity to ground to check for a harness short

5. 5

   Inspect the UCM and solenoid connectors for water intrusion, corrosion, or bent pins.

1. 1

   Prepare the Machine

   Park the loader on a level surface, lower the loader arms completely (or engage the cylinder lock if they must be raised), turn off the engine, and disconnect the negative battery cable to prevent electrical spikes.

2. 2

   Access the Hydrostatic Pumps

   Depending on your specific model, access the hydrostatic drive pumps by either raising the cab or removing the rear/belly access panels.

3. 3

   Locate the Solenoid

   Locate the Forward Pump Control Valve block on the left side of the hydrostatic pump assembly. Identify the Left (B) directional solenoid.

4. 4

   Harness Repair (If applicable)

   If the diagnostic checks revealed a harness short, trace the wire back from the solenoid to the UCM. Cut out the damaged section of the wire, solder in a new section of appropriately gauged wire, and seal it with marine-grade heat shrink tubing.

5. 5

   Solenoid Replacement (If applicable)

   If the solenoid coil is internally shorted, remove the retaining nut or bolt holding the coil to the valve stem. Slide the old coil off. Clean the valve stem, slide the new solenoid coil into place, and torque the retaining nut to OEM specifications.

6. 6

   Reassembly

   Reconnect the electrical connector to the solenoid, ensuring the weather-pack seal is seated correctly. Secure any loose wiring with zip ties to prevent future chafing.

7. 7

   Clear Codes and Test

   Reconnect the battery. Turn the ignition on and use a diagnostic tool (or the machine's display panel) to clear the UCM fault codes. Start the machine and test the left-side forward drive function to confirm the repair.