Case IH 17648 (F-5394-31) - ECU – Engine Control Unit (ECU): DEF/AdBlue dosing valve ECU driver open circuit.

The Engine Control Unit (ECU) has detected an open circuit in the driver circuit for the DEF (Diesel Exhaust Fluid) / AdBlue dosing valve. This means the electrical connection between the ECU and the dosing valve is broken, disconnected, or the internal driver inside the ECU has failed. As a result, the valve cannot be actuated to inject DEF into the Selective Catalytic Reduction (SCR) system, which will lead to an emissions failure and engine derate (inducement).

• VESTRUM CVX
• Case IH Austoft 9900 Sugarcane Harvesters
• Case IH Magnum AFS Connect Tractors

1. 1

   Visual Wiring Inspection: Check the wiring harness and connectors between the ECU and the DEF dosing valve for chafed wires, broken connections, pushed-out pins, or corrosion.

2. 2

   Continuity/Resistance Test: Disconnect the DEF dosing valve and test the internal solenoid for continuity. Infinite resistance (OL) indicates an open internal coil.

3. 3

   Electronic Service Tool Testing: Use a diagnostic tool (Case IH EST, Jaltest, or TEXA) to perform an 'AdBlue Dosing Valve Solenoid test' (UDVC/UDST) to verify if the ECU is sending the signal and if the valve mechanically responds.

4. 4

   Check for Related Codes: Look for related SPN 3361 codes (FMI 3, 4, 5, or 31) which indicate short circuits, open loads, or over-temperature conditions on the DEF dosing valve driver.

1. 1

   Safety First

   Turn off the machine, remove the key, and disconnect the battery to prevent electrical shorts while working on the ECU harness.

2. 2

   Harness Repair (If Applicable)

   If the diagnostic checks revealed a broken wire or corroded connector between the ECU and the dosing valve, repair the wiring harness or replace the pigtail connector.

3. 3

   Valve Replacement (If Applicable)

   If the dosing valve solenoid is internally open, remove the faulty DEF dosing valve from the exhaust aftertreatment system. (Note: Ensure the DEF system is purged/depressurized if required by the specific engine manual before removal).

4. 4

   Installation

   Install the new DEF dosing valve and securely reconnect the electrical harness.

5. 5

   Reassembly

   Reconnect the battery.

6. 6

   System Reset and Testing

   Connect your diagnostic service tool. Clear the inactive fault codes. Because this fault causes an emissions inducement (engine derate), you must perform an 'Inducement Unlock / Counter Reset' via the diagnostic tool once the physical repair is complete.

7. 7

   Verification

   Run a forced DEF dosing system control test to verify the new valve operates correctly and the open circuit code does not return.