Case IH 4375 – Engine ECU / DCU / UCM / Ground Drive Controller: DEF Pump Motor Control Signal / Swashplate Angle Sensor Plausibility

Code 4375 indicates the electrical signal to the DEF pump motor is out of range. It is often conflated with Swashplate Plausibility (Code 4752/4754), where the controller commands a specific hydraulic pump flow but the swashplate angle sensor reports a mismatched physical position.

• Steiger T4B
• TV380
• TR270
• SR series
• SV series
• Steiger
• Magnum
• Optum

1. 1

   For DEF Pump (Code 4375): Check the electrical signal to the DEF pump motor for an open circuit, short to ground, short to power, or over-temperature condition.

2. 2

   For Swashplate Plausibility (Code 4752/4754): Perform a mechanical pump isolation test by marking and removing the servo control coils from the pump stems (leaving them plugged in) to see if the machine still creeps.

3. 3

   For Swashplate Plausibility: With cluster power ON and engine OFF, back-probe pins 3 and 4 of the swashplate angle sensor connector to verify the 5V reference power supply (should read approximately 2.5V in neutral).

4. 4

   For Swashplate Plausibility: Perform a sweep test by slowly rotating the sensor and monitoring the multimeter for smooth voltage changes without dead spots.

1. 1

   Turn the machine's cluster power ON

   Do not start the engine.

2. 2

   Locate the swashplate angle sensors

   Mounted on the bottom of the hydrostatic pump (often protected by steel covers).

3. 3

   Back-probe Pin 3 and Pin 4

   Use a multimeter on the sensor connector.

4. 4

   Slightly loosen the sensor mounting bolts

   Expect minimal oil loss, as the only pressure present is head pressure from the hydraulic tank.

5. 5

   Carefully rotate the sensor

   Rotate until the multimeter reads 2.5V across both pins (e.g., a reading of 2.4V on pin 3 and 2.6V on pin 4 is considered normal and balanced).

6. 6

   Tighten the sensor mounting bolts

   Tighten to 27.4 in.-lb (3.1 N.m).

7. 7

   Restart the machine and verify

   Verify that the pump neutralizes properly and the 4752 code clears. If the sensor cannot be adjusted to 2.5V, it must be replaced.