Case IH 518653-21 - ICM – ICM: Fuel level sensor resistance short to VCC (power), open circuit or not configured

Critical failure in the fuel level sending unit circuit, preventing the module from reading the fuel level.

• MAGNUM AFS Connect
• Magnum 400 AFS Connect
• Steiger
• Puma

1. 1

   Verify ICM Configuration: Check through the diagnostic display that the fuel level sensor is properly enabled in the ICM software, as the code can trigger if not configured.

2. 2

   Inspect the Wiring Harness: Check the wiring from the ICM to the fuel tank sending unit. Look for chafed wires causing a short to power (VCC) or a severed wire causing an open circuit.

3. 3

   Bypass/Short Test: Disconnect the sensor plug at the top of the fuel tank and short the sensing wire to the ground wire. If the fuel gauge on the dash flashes empty or changes its reading, the wiring to the cab and the ICM are functioning correctly, confirming the sensor itself is the point of failure.

4. 4

   Multimeter Resistance Test: Measure the resistance across the pins of the fuel level sensor. If it reads out of limits (O.L.) or shows infinite resistance, the internal potentiometer of the sending unit is broken (open circuit).

1. 1

   Disconnect Power

   Disconnect the tractor's battery to prevent electrical sparks while working around the fuel tank.

2. 2

   Locate the Sensor

   Access the top of the main fuel tank where the fuel level sending unit is mounted.

3. 3

   Disconnect Harness

   Unplug the electrical connector from the fuel level sensor.

4. 4

   Remove Mounting Hardware

   Remove the mounting screws (typically 5 hex washer head screws) securing the sensor to the tank.

5. 5

   Extract the Sensor

   Carefully pull the old fuel level sensor assembly out of the tank. Remove and discard the old rubber gasket.

6. 6

   Install New Parts

   Place a new gasket (do not reuse the old one, as it will leak) and insert the new fuel level sensor into the tank.

7. 7

   Secure and Reconnect

   Tighten the mounting screws in a star pattern to ensure an even seal. Reconnect the electrical harness.

8. 8

   Test

   Reconnect the battery, turn the ignition key to the ON position, and verify that the fuel gauge registers the correct fuel level and the 518653-21 / 518653-20 fault code changes to inactive or clears from the ICM.