Case IH 19748 (F-5435-06) - ECU – DCU (Dosing Control Unit): DEF/AdBlue supply module pump motor ECU driver over temperature failure

The system has detected that the urea temperature in the pump module is too high, or a leakage test has failed, triggering an emergency shut-off. The internal temperature sensor of the pump module is reading out of range, or the pump motor's driver circuit inside the control unit has overheated. This is typically caused by an electrical short in the pump wiring, a blocked DEF line causing the pump to overwork, or an internal failure of the pump motor itself.

• VESTRUM CVX
• Case IH Steiger & Quadtrac Series: 350, 370, 400, 420, 450, 470, 500, 540, 550, 580, 600, 620
• Case IH Magnum Series: 235 - 340 (Series 4), 385, 400
• Case IH Axial-Flow Combines: 240 Series (7240, 8240, 9240) and newer 250/260 series
• Case IH Farmall Tractors: 40, 45, 50 (CVT models)

1. 1

   Verify Active Status: Check if the fault is currently active or stored. If the fault is active, the machine may enter an SCR Inducement derate (Torque reduction or creep mode).

2. 2

   Wiring Harness Inspection: Check the wiring of the DEF/AdBlue supply pump (often designated as component A-030) to see if there is a short circuit to the battery supply or ground. Specifically, release and inspect connector X-028C1 for melted pins or corrosion.

3. 3

   Temperature Plausibility Check: Use an electronic service tool to read the DEF tank temperature and the module box temperature. The DCU will flag this code if the module box temperature reads out of plausible bounds (e.g., below 16°F or above 167°F) due to a failed sensor.

4. 4

   Line Inspection: Inspect the DEF lines and the dosing valve for blockages or crystallization. A blocked line can cause the pump motor to draw excessive current, overheating the ECU driver.

1. 1

   Safety First

   Turn off the machine, remove the key, and disconnect the battery to prevent electrical arcing.

2. 2

   Isolate the Wiring

   Disconnect the wiring harness at the DEF supply module. Use a multimeter to test the harness between the DCU and the pump for continuity and shorts to ground/power. Repair any damaged wiring.

3. 3

   Replace the Module (If wiring is intact)

   If the wiring tests good and the lines are not blocked, the internal ECU driver for the pump motor or the internal temperature sensor has failed. The DEF/AdBlue supply module cannot be serviced internally and must be replaced as a complete unit.

4. 4

   Remove the Old Pump

   Disconnect the DEF fluid hoses (be prepared for minor fluid spillage) and remove the mounting hardware securing the DEF supply module to the tank/frame.

5. 5

   Install the New Pump

   Mount the replacement DEF supply module, reconnect the fluid lines securely, and plug in the electrical connector.

6. 6

   Fluid Check

   Ensure the DEF fluid in the tank is clean and free from contamination. Contaminated fluid is a leading cause of premature pump failure.

7. 7

   System Prime and Clear Codes

   Reconnect the battery. Use a diagnostic service tool to clear the 19748 fault code. Run a dynamic DEF leakage test or system prime command via the service tool to ensure the new pump builds pressure and has no leaks.