Case IH 17905 (F-3510-05) - ECU – Engine Control Module (ECM) / Engine ECU: ECM 5 volt sensor supply 2 under voltage failure only

The 5-volt reference circuit #2, which provides power to a specific group of engine sensors, has dropped below its acceptable voltage threshold. This condition is almost always caused by a short to ground in the wiring harness or an internally shorted sensor pulling the entire circuit's voltage down.

• VESTRUM CVX
• Farmall 115U Efficient Power
• Farmall 40
• Farmall 45
• Farmall 50

1. 1

   Consult your specific machine's wiring schematic to identify which sensors share '5 Volt Sensor Supply 2' (e.g., Engine Oil Rifle Pressure sensor)

2. 2

   Turn the key ON (engine OFF) and back-probe the 5V supply wire at one of the sensors on this circuit with a multimeter

3. 3

   Disconnect the sensors on Supply 2 one at a time. If the voltage jumps back up to approximately 5.0V when a specific sensor is unplugged, that sensor is internally shorted

4. 4

   If all sensors on the circuit are unplugged and the voltage remains low, inspect the wiring harness for chafing, pinched wires, or melted insulation between the sensors and the ECM

5. 5

   Disconnect the ECM harness and check the pins for corrosion, moisture, or bent terminals

1. 1

   Disconnect Power

   Turn off the ignition and disconnect the negative battery cable before performing electrical repairs.

2. 2

   Address the Short

   If a sensor failed: Replace the internally shorted sensor. If the harness failed: Locate the chafed/shorted section of the wiring harness. Splice and solder the damaged wires, then seal with heat-shrink tubing, or replace the affected harness section entirely.

3. 3

   Clean Connections

   Apply dielectric grease to the sensor and ECM connectors to prevent moisture intrusion.

4. 4

   Reassemble and Clear Codes

   Reconnect the battery, turn the key ON, and use the Case IH Electronic Service Tool (EST) to clear the inactive 17905 fault code.

5. 5

   Verify Repair

   Start the engine and verify that the 5V reference voltage remains stable and the code does not return.