New Holland UCM 5382 – UCM: Enhanced High-Flow Auxiliary Option: Reverse Solenoid (B) Supply Short to Ground

The control module has detected that the electrical supply circuit providing power to the Reverse Solenoid (B)—which controls the proportional relief valve (PRV) for the Enhanced High-Flow (EHF) auxiliary hydraulic pump—is shorted directly to the machine's chassis ground. This prevents the module from properly controlling the reverse flow of the high-flow auxiliary hydraulics.

• L218
• L220
• L223
• L225
• L230
• L234
• C227
• C232
• C238
• L318-L330
• C327-C338
• SR220
• SV250
• TR270
• TR320

1. 1

   Visual Harness Inspection: Inspect the wiring harness routing from the UCM to the EHF pump control valve block. Look for chafed insulation, pinched wires, or exposed copper touching the metal chassis, particularly where the harness routes near the loader arms or hydraulic lines.

2. 2

   Connector Check: Locate the Reverse Solenoid (B) on the EHF pump control block. Disconnect its Deutsch DT series connector. Inspect the pins for corrosion, pushed-back terminals, or water intrusion.

3. 3

   Solenoid Coil Test: With the connector unplugged, use a multimeter to measure the resistance between the solenoid's power terminal and the solenoid housing/ground. If there is continuity to ground, the solenoid coil is internally shorted.

4. 4

   Harness Short Test: With the solenoid unplugged and the battery disconnected, test the supply wire on the harness side for continuity to chassis ground. If continuity exists, the short is in the wiring harness between the UCM and the connector.

1. 1

   Safely Park the Machine

   Lower the loader arms completely (or engage the safety strut if they must be raised for access). Turn off the engine and disconnect the negative battery cable.

2. 2

   Relieve Hydraulic Pressure

   Turn the ignition ON (engine OFF) and cycle the hydraulic controls to relieve any residual pressure in the auxiliary circuit.

3. 3

   Isolate the Fault

   Based on the diagnostic checks, determine if the short is in the wiring harness or internal to the solenoid.

4. 4

   Repair Shorted Harness

   If the harness is shorted: Trace the supply wire back to the UCM. Locate the damaged section of the wire. Cut out the damaged section and splice in a new wire using weather-sealed heat-shrink butt connectors, or replace that section of the EHF jumper harness.

5. 5

   Replace Shorted Solenoid

   If the solenoid is shorted: Clean the area around the EHF pump control valve block to prevent dirt from entering the hydraulic system. Unscrew the retaining nut holding the Reverse Solenoid (B) coil to the proportional relief valve (PRV) cartridge. Slide the old solenoid coil off the cartridge. (If the cartridge itself is damaged or leaking, unthread the entire PRV cartridge and install a new one). Slide the new solenoid coil onto the valve cartridge and tighten the retaining nut to OEM torque specs.

6. 6

   Reassembly and Testing

   Reconnect the Deutsch DT connector. Reconnect the battery. Power on the machine, clear the UCM fault codes using the instrument cluster or an Electronic Service Tool (EST), and test the Enhanced High-Flow auxiliary hydraulics in both forward and reverse to verify the repair.