New Holland UCM 5381 – UCM: Enhanced High-Flow Auxiliary Option: Reverse Solenoid (B) Supply Open Circuit

The control module is attempting to send a 12V signal to the solenoid that controls the reverse flow of the Enhanced High-Flow (EHF) auxiliary hydraulic circuit, but it detects no electrical current. An "Open Circuit" (OC) typically indicates a disconnected plug, a severed wire in the harness, or a burned-out solenoid coil.

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• L230
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• SR130
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• SV185
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1. 1

   Locate the EHF directional control valve block and visually inspect the wiring harness leading to the Reverse Solenoid (B) for pinched, rubbed, or broken wires.

2. 2

   Disconnect the solenoid's Deutsch DT connector and check for pushed-back pins, moisture, or corrosion inside the plug.

3. 3

   Measure the resistance across the two pins on the solenoid coil using a multimeter. If it reads 'OL' (Open Line) or infinite resistance, the internal coil is broken/burned out.

4. 4

   Check the continuity of the supply wire from the UCM harness down to the solenoid connector to isolate a break in the wiring if the coil tests good.

1. 1

   Power Down

   Turn off the machine, lower the boom (or engage the boom lock), and disconnect the battery to prevent short circuits.

2. 2

   Locate the Valve

   Access the hydraulic control area and locate the EHF pump control PRV (Proportional Relief Valve) block. Identify the specific solenoid designated for "Reverse (B)".

3. 3

   Remove the Faulty Component

   Disconnect the Deutsch DT electrical connector. If the coil failed the resistance test, remove the retaining nut at the end of the cartridge valve and slide the faulty solenoid coil off the valve stem.

4. 4

   Install the New Part

   Slide the new solenoid coil onto the cartridge valve and tighten the retaining nut (do not over-tighten, as this can distort the cartridge).

5. 5

   Repair Wiring (If Applicable)

   If the diagnostic test pointed to a broken wire rather than a bad coil, splice and repair the wire using weather-sealed (heat-shrink) connectors.

6. 6

   Reassemble and Test

   Reconnect the electrical plug. Reconnect the battery. Start the machine, engage the hydraulic enable switch, and test the EHF auxiliary hydraulics in reverse to ensure the fault code goes inactive and the attachment receives flow.