Case IH 4744 – UCM: Left Swash Plate Angle Sensor Pin B Open Or Shorted To Ground

The controller has detected an open circuit or a short to ground on Pin B of the left pump's sensor circuit. When this signal is lost, the controller cannot verify the pump's displacement and will typically disable the drive system (tracks or wheels will not move) as a safety precaution to prevent uncommanded movement.

• skid steer
• Skid Steer Loaders (SSL)
• Compact Track Loaders (CTL)
• TR270
• TV380
• SR200
• SR220
• SV250
• SV300
• C227
• C232
• C234
• C238
• L213
• L223

1. 1

   Check hydraulic fluid condition and temperature — cold or water-contaminated (milky) fluid can cause sluggish swash plate movement and trigger false codes

2. 2

   Visually inspect the left hydrostatic travel pump and locate the swash plate angle sensor mounted on the bottom

3. 3

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

4. 4

   Using a multimeter, check Pin B on the machine-side harness for continuity to ground (short to ground) or a broken wire leading back to the UCM (open circuit)

5. 5

   If the wiring harness tests good from the sensor connector back to the UCM, the internal circuitry of the sensor itself has likely failed

1. 1

   Preparation

   Park the machine on a level surface, lower the loader arms (or engage the cylinder lock), turn off the engine, and disconnect the battery to prevent electrical shorts.

2. 2

   Access the Pump

   Lift the cab or open the necessary access panels to reach the hydrostatic drive pumps.

3. 3

   Remove the Sensor

   Locate the left swash plate angle sensor on the pump housing. Disconnect the electrical pigtail. Remove the retaining screws holding the sensor to the pump body.

4. 4

   Install the New Sensor

   Clean the mounting surface on the pump. Install the new OEM angle sensor and secure it with the retaining screws (screws are often not supplied with the sensor and must be reused or procured locally).

5. 5

   Reconnect and Reassemble

   Plug the electrical connector back into the sensor harness. Ensure the wire is routed safely away from moving parts or high-heat sources. Lower the cab/replace access panels.

6. 6

   Clear Codes and Test

   Reconnect the battery. Use the Case IH Electronic Service Tool (EST) to clear the stored UCM fault codes. Start the machine, allow the hydraulic fluid to warm up, and test the left drive function in both forward and reverse to ensure the code does not return.