Case IH 4745 – UCM (Universal Control Module): Left Swash Plate Angle Sensor Pin B Shorted To Power

The control module is receiving a voltage signal on Pin B of the left sensor's circuit that is higher than the expected maximum range, meaning the circuit is shorted to a power source (such as a 5V reference or 12V battery voltage).

• skid steer
• Skid Steer Loaders (SSL)
• Compact Track Loaders (CTL)
• TR270
• TR320
• TV380
• SR210
• SR220
• SV250
• SV300

1. 1

   Confirm that the joysticks are returning to the neutral position and that there are no electrical issues with the joystick harness.

2. 2

   Inspect the wiring harness and connectors between the Left Swash Plate Angle Sensor and the UCM for rubbed, chafed, or melted wires bridging Pin B to power.

3. 3

   Disconnect the sensor, turn the key ON, and probe Pin B on the harness side to check for voltage indicating a short in the machine's wiring harness.

4. 4

   Verify that the pins at the UCM connector are not bent, corroded, or bridged by moisture/debris.

5. 5

   Use the Electronic Service Tool (EST) 'monitor' function to view the live parameters of the Left Hand Pump Angle Sensor to see if the voltage is pegged high.

1. 1

   Prepare the Machine

   Park the machine on a level surface, lower the loader arms (or engage the mechanical loader arm lock), turn off the engine, and disconnect the battery.

2. 2

   Locate the Sensor

   Access the hydrostatic drive pump assembly (commonly a Bosch Rexroth tandem pump). Locate the Left Swash Plate Angle Sensor on the left pump housing.

3. 3

   Harness Repair

   If the diagnostic checks revealed a short in the wiring, repair or replace the damaged section of the harness.

4. 4

   Sensor Replacement

   If the harness tests good, the sensor is internally shorted. Disconnect the electrical connector, remove the mounting screws, and remove the faulty sensor.

5. 5

   Install New Sensor

   Install the replacement sensor. (Note: OEM documentation states that mounting screws are not serviced with the sensor and must be procured locally or reused if in good condition).

6. 6

   Reassembly

   Reconnect the electrical connector and the battery.

7. 7

   Calibration

   Connect the Electronic Service Tool (EST). Clear the inactive fault codes. You must perform a swash plate angle sensor centering/calibration procedure using the EST to ensure the UCM learns the true neutral position of the new sensor.