New Holland UCM 4741 – UCM (Universal Control Module): Left Swash Plate Angle Sensor – Pin A Short to Ground / Open Circuit

The Universal Control Module (UCM) has detected a critical electrical failure on the "Pin A" circuit of the sensor that monitors the angle of the left hydrostatic pump's swash plate. The UCM is seeing either zero voltage (a short to the chassis ground) or infinite resistance (an open circuit/broken wire), which prevents the module from knowing the position of the left ground drive pump.

• L213
• L215
• L218
• L220
• L223
• L225
• L230
• C227
• C232
• C238

1. 1

   Inspect the wiring harness and the electrical connector at the Left Swash Plate Angle Sensor (located on the tandem hydrostatic pump) for physical damage, corrosion, or pushed-out pins.

2. 2

   Perform an open circuit test: Disconnect the sensor and the UCM harness. Use a multimeter to check for continuity on the wire corresponding to Pin A between the sensor connector and the UCM. Infinite resistance indicates a broken wire.

3. 3

   Perform a short to ground test: With both ends disconnected, test the Pin A wire for continuity to the machine's chassis ground. Continuity indicates the wire is rubbing against the frame and shorting out.

4. 4

   If the wiring harness passes both continuity and ground tests, the internal circuitry of the Swash Plate Angle Sensor has failed.

1. 1

   Turn off the machine and engage the battery disconnect switch (or disconnect the negative battery cable) to prevent electrical shorts.

2. 2

   Access the tandem hydrostatic pump assembly and locate the Left Swash Plate Angle Sensor.

3. 3

   If the diagnostic checks revealed a wiring issue, repair or replace the affected section of the machine's wiring harness.

4. 4

   If the wiring is intact, disconnect the electrical connector from the sensor.

5. 5

   Remove the mounting screws holding the sensor to the pump housing.

6. 6

   Install the new Swash Plate Angle Sensor and tighten the mounting screws.

7. 7

   Reconnect the electrical harness to the sensor.

8. 8

   Reconnect the battery / turn on the disconnect switch.

9. 9

   Clear the fault codes via the instrument cluster display or the Electronic Service Tool (EST).

10. 10

    Perform a Ground Drive Calibration.

    Replacing the sensor will likely trigger code 1212 (Ground Drive Calibration Not Complete) until the UCM is recalibrated to the new sensor's baseline.