New Holland UCM 4734 – UCM: Right Swash Plate Angle Sensor - Pin B Short to Ground / Open Circuit

The controller detects that the signal circuit on Pin B of the right-hand pump's sensor is either completely broken (open circuit) or has chafed and is touching bare metal (short to ground), which typically disables the ground drive for safety.

• New Holland L-Series Skid Steer Loaders (L218, L220, L228)
• New Holland C-Series Compact Track Loaders
• Case SR Series
• Case SV Series
• Case TR Series
• Case TV Series
• Case TR270
• Case SV250

1. 1

   Visually inspect the wiring harness leading to the Right Swash Plate Angle Sensor for pinched wires, chafing against the chassis, or rodent damage.

2. 2

   Disconnect the sensor harness and inspect the connector for water intrusion, corrosion, or pushed-out pins.

3. 3

   Perform a continuity test on the Pin B wire from the sensor connector back to the UCM harness connector to check for an open circuit.

4. 4

   Test the Pin B wire for continuity to the machine's chassis ground with the UCM and sensor unplugged to check for a short to ground.

1. 1

   Prepare machine

   Park the machine on a level surface, lower the boom, turn off the engine, and disconnect the negative battery cable.

2. 2

   Access pumps

   Gain access to the hydrostatic drive pumps (usually requires lifting the cab or accessing through the belly/rear panels depending on the model).

3. 3

   Locate sensor

   Locate the Right Swash Plate Angle Sensor on the right-side drive pump.

4. 4

   Repair wiring

   If wiring failed the diagnostic tests: Repair the broken or shorted wire on the Pin B circuit. Splice and heat-shrink the repair, then secure it in protective loom away from vibration points.

5. 5

   Disconnect sensor

   If wiring passed the diagnostic tests: The sensor has failed internally. Disconnect the sensor's electrical connector.

6. 6

   Remove sensor

   Remove the mounting screws securing the swash plate angle sensor to the pump housing.

7. 7

   Install new sensor

   Install the new sensor and tighten the mounting screws (note: OEM screws are often procured locally if damaged).

8. 8

   Reconnect harness

   Reconnect the electrical harness.

9. 9

   Clear codes

   Reconnect the battery, power on the machine, and use an Electronic Service Tool (EST) to clear the UCM codes.

10. 10

    Test drive

    Test drive the machine to verify that the ground drive functions normally and the code does not return.