Case IH 19106 – Engine Control Unit (ECU) or SCR/DEF Control Module (DCU): DEF/AdBlue tank heater actuator short circuit to ground failure

The control module has detected that the electrical circuit controlling the DEF (Diesel Exhaust Fluid) tank heater coolant valve solenoid is shorted to ground. When this occurs, the valve cannot properly regulate the flow of engine coolant to the DEF tank heater, which is critical for preventing the DEF fluid from freezing in cold weather.

• Tier 4b
• 240 Series Axial-Flow Combines
• Magnum series
• Steiger series
• Farmall series
• Maxxum
• Puma

1. 1

   Visual Wiring Inspection: Inspect the wiring harness and connectors leading to the DEF tank heater coolant valve solenoid. Look for chafed insulation, melted wires, or pinched harnesses that could be shorting directly to the machine's chassis (ground).

2. 2

   Solenoid Resistance Test: Disconnect the electrical connector at the DEF tank heater actuator. Use a multimeter to check the resistance across the solenoid pins and from the pins to the actuator housing.

3. 3

   Hose Routing Verification: Verify that the DEF tank coolant hoses are installed correctly (e.g., the DEF heater line with the 'red' band must be connected to the top tube running to the front part of the engine head).

4. 4

   Circuit Testing: Turn the key ON (engine OFF) and test the harness side of the connector for proper voltage supply and ground to ensure the short is not located deeper in the main engine harness.

1. 1

   Preparation

   Turn off the machine, remove the key, and disconnect the battery cables. Ensure the engine is cool before beginning to prevent burns from hot engine coolant.

2. 2

   Locate the Valve

   Locate the DEF tank heater coolant control valve. Depending on the model, it is typically mounted near the rear of the engine block or inline near the DEF tank.

3. 3

   Disconnect Hoses

   Loosen the hose clamps and disconnect the DEF tank heater coolant hoses from the valve. Cap and plug all hose openings immediately to prevent coolant loss and system contamination.

4. 4

   Remove the Actuator

   Disconnect the electrical connector from the DEF tank heater valve. Remove the retaining bolts or mounting bracket holding the valve in place and remove the faulty unit.

5. 5

   Install the New Part

   Mount the replacement DEF tank heater valve and secure the retaining hardware.

6. 6

   Reconnect Hoses and Wiring

   Reconnect the coolant hoses, ensuring they are installed in the correct orientation (e.g., red banded hose to the correct port). Tighten the hose clamps and plug in the electrical connector.

7. 7

   Refill and Test

   Reconnect the battery. Top off the engine coolant if any was lost during the procedure.

8. 8

   Clear Codes

   Connect a diagnostic scan tool to clear fault code 19106 (and any related inducement codes). Run the engine, check for coolant leaks at the valve, and verify that the code does not return.