Case IH 19262 (F-3363-03) - ECU – DCU (Dosing Control Unit) or Engine ECU: DEF/AdBlue tank heater actuator short circuit to battery failure

The system's monitoring logic has detected that the circuit controlling the DEF tank heater coolant valve solenoid is shorted to a high voltage source (battery voltage). When this occurs, the valve cannot be properly controlled, which can lead to the DEF tank overheating or failing to thaw in freezing conditions.

• VESTRUM CVX
• 240 Series Axial-Flow Combines
• Magnum (235-340 Series 4, 290, 310)
• Steiger
• Puma
• Maxxum
• Farmall

1. 1

   Inspect the wiring harness between the DCU/ECU and the DEF tank heater coolant valve solenoid for rubbed, melted, or pinched wires causing a short to a high-voltage source (battery).

2. 2

   Test the DEF heater control valve solenoid for an internal short circuit.

3. 3

   Check the mechanical operation of the heating valve to ensure it is not stuck open.

4. 4

   Verify DEF tank coolant hose routing. Ensure hoses are not installed backward (on Fargo-built tractors, the red band line must connect to the top tube running to the front of the engine head).

1. 1

   Power Down

   Turn off the machine and disconnect the battery before performing service on the electrical system.

2. 2

   Repair Wiring

   If the diagnostic checks revealed a short to battery in the wiring harness, repair or replace the damaged section of the harness.

3. 3

   Replace the Valve

   If the wiring is intact but the fault is active, the solenoid valve is defective. Drain the necessary amount of engine coolant to prevent spills.

4. 4

   Remove the Old Valve

   Disconnect the electrical connector and the coolant hoses from the DEF tank heater control valve.

5. 5

   Install the New Valve

   Install the replacement valve. Crucial Note: This is a directional valve. If assembled in the opposite direction, the valve cannot cut off coolant flow, which will cause high-temperature coolant to constantly flow to the DEF tank.

6. 6

   Reassemble and Refill

   Reconnect the hoses (ensuring correct flow direction) and the electrical connector. Refill the coolant.

7. 7

   Clear Codes

   Reconnect the battery, turn the key on, and use the diagnostic display or service tool to erase the fault code and verify normal operation.