New Holland UCM 4383 – UCM: Ground Drive: Solenoids Return Open Circuit

The controller has detected a break in electrical continuity (an open circuit) on the common return (ground) side of the wiring circuit that operates the directional solenoids responsible for the reverse function of the hydrostatic ground drive pumps.

• L213
• L215
• L218
• L220
• L223
• L225
• L228
• L230
• C227
• C232
• C238
• SR175
• C185
• C190
• L180
• L185
• L190

1. 1

   Turn the battery quick-disconnect switch to the OFF position or disconnect the negative battery cable before probing sensitive UCM circuits

2. 2

   Inspect the wiring harness between the UCM and the ground drive pump control valves. Look for chafed wires, broken lines, or disconnected plugs, specifically focusing on the common return/ground wire for the reverse solenoids

3. 3

   Disconnect the UCM and the reverse pump control valve solenoids. Check for pushed-back pins, corrosion, or moisture inside the connectors

4. 4

   Use a multimeter to measure the resistance across the reverse pump control solenoid coils. An infinite reading (OL) indicates the solenoid coil itself has failed open and requires replacement

5. 5

   Verify the condition of the UCM unswitched fuse, UCM battery fuse, and UCM 2SPD fuse in the electrical distribution box

1. 1

   Secure the Machine

   Park the skid steer on level ground. Raise the boom and rest it securely on the boom locks. Engage the parking brake and put the Service/Run switch in the "SERVICE" position.

2. 2

   Isolate Power

   Disconnect the negative battery cable.

3. 3

   Locate the Solenoids

   Access the primary hydrostatic ground drive pump assembly. Locate the directional control valve block (often referred to as the reverse pump control valves).

4. 4

   Repair Wiring (If Applicable)

   If the diagnostic checks revealed a broken return wire in the harness, splice and seal the wire using OEM-approved heat-shrink connectors.

5. 5

   Replace Solenoid (If Applicable)

   If the solenoid coil tested open, disconnect the electrical plug. Remove the retaining nut holding the solenoid coil to the valve stem and slide the old coil off. Slide the new solenoid coil onto the stem and torque the retaining nut to OEM specifications.

6. 6

   Reassembly

   Reconnect the electrical harness to the solenoid. Reconnect the negative battery cable.

7. 7

   Clear Codes and Calibrate

   Use a diagnostic tool or DTC eraser to clear the UCM 4383 code. You may need to perform a "Ground Drive Calibration" (associated with calibration function code 1212) to ensure the UCM properly recognizes the new solenoid parameters.

8. 8

   Test Operation

   Start the machine and slowly move the ground drive control lever into the REVERSE position under load to verify that the hydrostatic piston pumps engage smoothly without throwing the code.