Case IH 19872 (F-519294-31) - ECU – Engine Control Unit (ECU): Power stage error in HCU for DEF/AdBlue Supply Module Heater

The system has detected a general fault, open load, or short circuit in the internal power stage that drives the heater inside the Diesel Exhaust Fluid (DEF) Supply Module (the pump unit). Because DEF freezes at 11°C (12°F), the system relies on this heater to thaw the fluid; if the heater driver fails, the emissions system cannot function in cold weather.

• VESTRUM CVX
• Magnum (180-370)
• Steiger (350-600)
• Puma (130-215)
• Maxxum (110-140)
• Optum
• Vestrum
• Farmall series
• Patriot (4430)
• Titan series
• Farmlift series
• Axial-Flow 5130
• Axial-Flow 6130
• Axial-Flow 7130
• Axial-Flow 7230
• Axial-Flow 8230
• Axial-Flow 9230

1. 1

   Check the electrical wiring and connectors between the ECU, the HCU, and the DEF Supply Module for chafing, corrosion, or disconnected pins.

2. 2

   Test the circuit between the HCU and the DEF Supply Module for a short to battery or short to ground.

3. 3

   Disconnect the DEF Supply Module and measure the resistance of the internal heater. An open circuit or a dead short indicates the heater inside the pump has failed.

4. 4

   Verify that the HCU is receiving proper voltage and has a clean ground. Check the dedicated HCU fuse (often labeled X-BATT_HCU).

1. 1

   Clear and Verify

   Turn off the ignition, clear the DTCs using a diagnostic scan tool, and cycle the key to see if the code is an active hard fault.

2. 2

   Inspect the Harness

   Physically trace the wiring harness from the HCU to the DEF Supply Module (mounted on/near the DEF tank). Repair any damaged wires.

3. 3

   Test the Supply Module

   If the wiring is intact, test the DEF Supply Module's internal heater. If the heater is shorted, the entire DEF Supply Module (pump) must be replaced, as the heater is integrated into the unit.

4. 4

   Replace the HCU (if necessary)

   If the wiring is good and the DEF Supply Module heater tests within specification, the fault lies within the HCU itself (an internal power stage failure). The HCU must be replaced.

5. 5

   Reprogramming

   Note that replacing emissions control modules or the DEF Supply Module may require a diagnostic tool to prime the system, reset inducement counters, and pair the new module to the ECU.