New Holland UCM 4071 – UCM: Ground Drive: Solenoid Left (B) Supply Open Circuit

The control module has detected a break in the electrical circuit supplying power to the left ground drive directional solenoid (Solenoid B). This open circuit prevents the solenoid from actuating the forward pump control valve, resulting in a loss of drive function or steering control on the left side of the machine.

• New Holland 200 Series Skid Steer Loaders
• New Holland Compact Track Loaders
• L213
• L218
• L220
• L228
• C-Series CTLs
• Case Alpha Series
• SR130
• SR160
• SR175

1. 1

   Visually inspect the wiring harness leading to Solenoid B on the left ground drive pump control valve for physical damage, chafing, or severed wires.

2. 2

   Disconnect the harness at the left ground drive solenoid and check the connector for water intrusion, corrosion, or pushed-out pins.

3. 3

   Measure the resistance across the pins of the solenoid coil using a multimeter to check for an internal open circuit (infinite resistance/OL).

4. 4

   Check the continuity of the supply wire from the solenoid connector back to the UCM to locate any breaks in the harness.

1. 1

   Power Down

   Turn off the machine and engage the battery disconnect switch (if equipped) or disconnect the negative battery cable to protect the UCM.

2. 2

   Access the Pump

   Gain access to the hydrostatic drive pumps (usually requires raising the cab/operator platform safely using the mechanical lock).

3. 3

   Isolate the Fault

   Based on the diagnostic checks, determine if the fault is in the wiring harness or the solenoid itself.

4. 4

   Repair Wiring (If Applicable)

   If a wire is broken between the UCM and the solenoid, splice and repair the wire using weather-sealed heat-shrink connectors.

5. 5

   Replace Solenoid (If Applicable)

   If the solenoid coil is open, remove the retaining nut holding the solenoid coil to the directional valve stem. Slide the old coil off, slide the new coil on, and torque the retaining nut to OEM specifications.

6. 6

   Reassemble and Test

   Reconnect the electrical connector, lower the cab, reconnect the battery, and clear the UCM fault codes. Test the machine's left-side ground drive in forward and reverse to ensure the code does not return.