Case IH 19064 (F-519294-05) - ECU – DCU: Open circuit in the internal heater of the DEF Pump Supply Module

Voltage supply internal heaters 1 (UB1) electrical | Open circuit to UB1 | P20C5 Pump module - Internal heating - open circuit. The DEF pump supply module contains an internal heater to prevent the urea fluid from freezing in cold weather. The Heater Control Unit (HCU) monitors the line heaters and the pump heater. When the controller detects a break in the electrical circuit (open circuit) for the pump's internal heater, it logs this fault. If left unresolved, the DEF fluid may freeze, leading to emissions derates and power loss.

• VESTRUM CVX
• Magnum 180
• Magnum 190
• Magnum 200
• Magnum 210
• Magnum 220
• Magnum 225
• Magnum 235
• Magnum 240
• Magnum 250
• Magnum 260
• Magnum 290
• Magnum 340
• Magnum 370
• Steiger 350
• Steiger 400
• Steiger 450
• Steiger 500
• Steiger 550
• Steiger 600
• Puma 130
• Puma 145
• Puma 150
• Puma 160
• Puma 170
• Puma 185
• Puma 200
• Puma 215
• Puma 230
• Puma 240
• Maxxum 110
• Maxxum 115
• Maxxum 120
• Maxxum 125
• Maxxum 130
• Maxxum 140
• Axial-Flow Combine 5130
• Axial-Flow Combine 6130
• Axial-Flow Combine 7130
• Axial-Flow Combine 7230
• Axial-Flow Combine 8230
• Axial-Flow Combine 9230
• Patriot Sprayer 2250
• Patriot Sprayer 3240
• Patriot Sprayer 3340
• Patriot Sprayer 4430

1. 1

   Visually inspect the wiring harness and connectors leading to the DEF Pump Supply Module for physical damage, corrosion, or loose pins.

2. 2

   Disconnect the DEF pump supply module and use a multimeter to measure the resistance of the internal heater pins on the pump side. If the resistance is infinite (open), the internal heater has failed.

3. 3

   If the pump's internal heater tests good, check the machine-side wiring harness for continuity back to the HCU/DCU to rule out a broken wire or bad ground.

4. 4

   Verify that the HCU is receiving proper supply voltage and that no related fuses are blown.

1. 1

   Preparation

   Turn off the ignition and disconnect the battery ground cable to prevent damage to the electronic monitoring system. Allow the exhaust and DEF system to cool.

2. 2

   Clean the Area

   Thoroughly clean the area around the DEF pump supply module. The DEF system is highly sensitive to contamination; even microscopic dirt can ruin the doser injector.

3. 3

   Disconnect

   Relieve any residual pressure in the lines. Disconnect the electrical harness connectors and the DEF fluid lines (suction, pressure, and backflow) from the supply module.

4. 4

   Removal

   Unbolt the supply module bracket from its mounting location (often near the DEF tank) and remove the faulty unit.

5. 5

   Installation

   Mount the new DEF pump supply module. Reconnect the DEF lines, ensuring they click securely into place, and plug in the electrical connectors.

6. 6

   Reassembly & Calibration

   Reconnect the battery ground cable. Use a diagnostic scan tool to clear the 19064 / P20C5 fault codes. Note: A new Bosch supply module will require programming/calibration to the vehicle's ECU/DCU to function correctly.

7. 7

   Testing

   Run a system test via the scan tool to prime the DEF lines and verify that the heater circuit is operating without throwing an open load code.