New Holland UCM 4371 – UCM: Ground Drive: Solenoid Left (B) Supply Open Circuit

The control module has detected an open circuit in the electrical supply line to the left ground drive solenoid (B), meaning the electrical path is broken due to a severed wire, disconnected or corroded harness plug, or an internal failure (burned-out coil) within the solenoid itself. The module cannot send the required electrical current to control the left ground drive pump, resulting in a loss of drive function or steering control on the left side.

• L213
• L215
• L218
• L220
• L223
• L225
• L230
• L316
• L318
• L320
• C227
• C232
• C238

1. 1

   Visual Inspection: Inspect the wiring harness running from the UCM to the left ground drive pump. Look for obvious signs of chafing, pinched wires, or rodent damage.

2. 2

   Connector Check: Disconnect the plug at the left ground drive solenoid (B). Inspect the pins for corrosion, pushed-back terminals, or moisture ingress.

3. 3

   Coil Resistance Test: Using a multimeter, measure the resistance across the two pins of the left ground drive solenoid. If the multimeter reads 'OL' (Open Loop) or infinite resistance, the solenoid coil has failed internally and must be replaced.

4. 4

   Harness Continuity Test: If the solenoid tests good, check the continuity of the supply and ground wires from the UCM harness connector to the solenoid connector to locate the break in the wiring.

1. 1

   Safety First

   Park the machine on level ground, lower the loader arms (or engage the cylinder lock), engage the parking brake, and turn off the engine.

2. 2

   Disconnect Power

   Disconnect the negative battery cable to prevent electrical shorts during the repair.

3. 3

   Access the Pump

   Tilt the cab or open the rear access panels as required by your specific model to gain access to the hydrostatic drive pumps.

4. 4

   Locate the Solenoid

   Locate the left ground drive pump (often a Sauer Danfoss unit) and identify Solenoid B.

5. 5

   Remove the Faulty Component

   If the wiring is broken: Splice and repair the broken wire using weather-sealed heat-shrink connectors, or replace the damaged harness section. If the solenoid is faulty: Unplug the electrical connector. Remove the retaining nut at the end of the solenoid valve stem. Slide the faulty solenoid coil off the cartridge valve.

6. 6

   Install the New Part

   Slide the new solenoid coil onto the valve stem and tighten the retaining nut to the OEM torque specification. Reconnect the electrical harness plug securely.

7. 7

   Reassemble and Test

   Lower the cab/close panels, reconnect the negative battery cable, and turn the key on. Clear the UCM fault codes using the instrument cluster or a diagnostic service tool. Start the machine and test the ground drive to ensure the code does not return and the machine tracks straight.