Case IH F-3363-05 - ECU – Engine Control Unit (ECU): DEF/AdBlue tank heater actuator open load failure / DEF Tank Heater Solenoid Current Low

The control module has detected an open circuit, a disconnected wire, or an abnormally low current draw in the drive circuit that commands the DEF (urea) tank coolant heating valve/solenoid.

• MAGNUM AFS Connect
• Case IH Steiger & Quadtrac Tractors (e.g., Steiger 580 Quad)
• Case IH Magnum Tractors (e.g., 235, 260, 290, 315, 340)
• Case IH Axial-Flow Combines (e.g., 240 and 250 Series)
• Case IH Puma and Maxxum Tractors

1. 1

   Inspect the Wiring and Connectors: Locate the DEF tank heater solenoid (often located at the back of the engine block or inline with the coolant hoses running to the DEF tank).

2. 2

   Check for Pushed-Back Pins: Disconnect the plug and ensure all pins are fully seated and locked into the connector housing.

3. 3

   Test the DEF Heater Main Relay: The EEM4 monitoring system will throw an open load fault if the DEF heater main relay or its wiring is defective.

4. 4

   Check Valve Orientation and Operation: Ensure the heater control valve is not mechanically stuck open. Furthermore, verify the coolant hoses are routed correctly; if the directional valve was previously installed backward, it cannot cut off coolant flow, which leads to continuous hot coolant circulating and overheating the DEF tank.

1. 1

   Verify fault code

   Pull the machine into the shop and hook up the Case IH EST (Electronic Service Tool) laptop to verify the active 3363-05 code.

2. 2

   Access solenoid valve

   Safely access the DEF heater solenoid valve at the back of the motor.

3. 3

   Inspect wiring and pins

   Disconnect the wiring plug to the solenoid. Inspect the harness side and the component side for corrosion, broken wires, or pushed-back pins.

4. 4

   Reseat pins

   If a pin is pushed back, reseat it properly into the connector until it clicks.

5. 5

   Test solenoid resistance

   If the wiring is intact but the solenoid has an internal open circuit (test for infinite resistance with a multimeter), the heater control valve must be replaced.

6. 6

   Replace heater control valve

   To replace the valve, clamp off the engine coolant lines to prevent fluid loss, remove the defective actuator/valve assembly, and install the new one. Note: On Fargo-built tractors, ensure the DEF heater line with the 'red' band is connected to the top tube running to the front part of the engine head.

7. 7

   Reconnect components

   Reconnect the electrical plug and remove the coolant line clamps.

8. 8

   Clear fault codes

   Using the EST laptop, clear the fault codes.

9. 9

   Run verification test

   Run a fault verification test and start the tractor, allowing it to reach normal operating temperature to ensure the code does not return and there are no coolant leaks.