Case IH 518653-20 - ICM – ICM: Resistance fuel level sensor short to VCC or open circuit or not configured.

The control module is detecting that the electrical resistance from the fuel tank sending unit is either infinite (an open circuit/broken wire), shorted to a voltage source (VCC), or the sensor parameter has lost its configuration in the system software.

• MAGNUM AFS Connect
• Magnum 380
• Magnum 400
• MX180
• MX200
• MX220
• MX240
• MX270

1. 1

   Visual Inspection: Locate the fuel level sensor on the fuel tank. Inspect the sensor's electrical connector for corrosion, backed-out pins, or moisture, which commonly cause open circuits.

2. 2

   Wiring Harness Test: Disconnect the sensor and use a multimeter to check the wiring harness going back to the ICM. Test for continuity (to rule out a broken wire) and test for voltage on the signal wire (to rule out a short to VCC).

3. 3

   Sensor Resistance Test: Measure the resistance across the terminals of the fuel level sensor itself. If the multimeter reads 'OL' (infinite resistance), the internal resistor board of the sending unit has failed.

4. 4

   Ground Check: Verify that the sensor's ground wire is clean and securely fastened. A bad ground will mimic an open circuit.

5. 5

   Configuration Check: If the machine recently had a software update or module replacement, verify through the diagnostic menu that the fuel level sensor is properly configured in the ICM.

1. 1

   Prep the Machine

   Park the tractor on a level surface, turn off the engine, and disconnect the battery to prevent electrical spikes.

2. 2

   Access the Sensor

   Clean the area around the fuel level sensor on top of the fuel tank to prevent dirt from falling into the tank during removal.

3. 3

   Disconnect and Remove

   Unplug the electrical connector. Remove the retaining screws or locking ring holding the sensor in place.

4. 4

   Extract the Sensor

   Carefully pull the sending unit assembly straight up and out of the tank, being careful not to bend the float arm.

5. 5

   Install the New Part

   Insert the new fuel level sensor using a new OEM gasket or O-ring to prevent fuel leaks. Secure the retaining screws/ring.

6. 6

   Repair Wiring (If Applicable)

   If the diagnostic checks pointed to a harness issue rather than the sensor, splice and heat-shrink any broken wires, or replace the damaged connector pigtail.

7. 7

   Reassemble and Clear Codes

   Reconnect the electrical plug and the battery. Turn the ignition on to verify the fuel gauge registers the correct fuel level. Clear the 518653-20 fault code from the ICM using the tractor's diagnostic interface.