Case IH 19895 – Engine ECU: Water pump inlet pressure sensor voltage is higher than expected

The Engine ECU is receiving a voltage signal from the water pump inlet pressure sensor that exceeds the normal operating range (FMI 3), indicating that the sensor's signal wire is shorted to a power source or the sensor has failed internally.

• Tier 4b
• 240 Series Axial-Flow® Combines

1. 1

   Visually inspect the wiring harness leading to the water pump inlet pressure sensor for chafing, melting, or pinched wires that could cause a short to a voltage source.

2. 2

   Disconnect the sensor and inspect the pins on both the sensor and the harness side for corrosion, moisture, or bent pins.

3. 3

   With the key ON and the sensor disconnected, use a multimeter to check the signal wire on the harness side. If it reads a full 5V or 12V, the wiring harness is shorted to power.

4. 4

   Check if other 5V reference sensors are throwing similar 'voltage high' codes, which would indicate a shared 5V supply circuit is shorted to the battery.

1. 1

   Power Down

   Turn off the machine and turn the battery disconnect switch to the OFF position.

2. 2

   Isolate the Fault

   Disconnect the water pump inlet pressure sensor.

3. 3

   Harness Repair

   If the diagnostic voltage test revealed a short to a high voltage source in the harness, trace the wiring back to the Engine ECU. Locate the damaged section of the harness, repair the shorted wires, and seal them with heat-shrink tubing.

4. 4

   Sensor Replacement

   If the wiring harness tests good (no shorts to power), the sensor itself has an internal short. Unthread the old water pump inlet pressure sensor from the water pump housing and install the new sensor.

5. 5

   Reassembly & Clearing Codes

   Reconnect the sensor harness. Turn the battery disconnect switch back ON. Connect your Case IH diagnostic tool (or use the in-cab display) to clear the inactive fault codes.

6. 6

   Verification

   Start the engine and verify that the warning lights remain off and the machine does not default to low idle.