New Holland DCU 19065 – DCU: Voltage supply internal heaters 1 (UB1) electrical | Short to bat at UB1 with Key 15 off | Pump module - Internal heating - short circuit high

This code indicates a critical electrical failure within the Diesel Exhaust Fluid (DEF) / AdBlue system. Specifically, the engine's diagnostic system has detected a short circuit to battery voltage on the internal heating circuit (UB1) inside the DEF pump module while the ignition key is in the 'off' position.

• T6 series
• T7 series
• T8 series
• T9 series
• TS6 series
• CR/CX series
• Speedrower series
• LM series
• TH series
• Magnum
• Puma
• Maxxum
• Optum
• Steiger
• Patriot sprayers

1. 1

   Inspect the wiring harness connecting the DCU to the DEF pump module for chafed wires, melted insulation, or pinched areas that could cause a short to battery voltage.

2. 2

   Disconnect the DEF pump module connector and check for water intrusion, highly corrosive DEF fluid crystallization, or bent/damaged pins.

3. 3

   With the module disconnected and the key off, use a multimeter to test the UB1 supply pin on the harness side for voltage. If voltage is present, the wiring harness is shorted to power. If no voltage is present, the short circuit is internal to the DEF pump module.

1. 1

   Preparation

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

2. 2

   Drain/Disconnect

   Relieve any pressure in the DEF lines. Disconnect the DEF suction, pressure, and backflow lines from the pump module. Cap the lines immediately to prevent contamination.

3. 3

   Remove Module

   Disconnect the main electrical harness from the pump module. Unbolt the module from its mounting bracket on the DEF tank assembly.

4. 4

   Install New Module

   Mount the replacement DEF pump module (DeNOx supply module) and secure the bolts.

5. 5

   Reconnect

   Remove the caps and reconnect the DEF fluid lines, ensuring they click securely into place. Reconnect the electrical harness.

6. 6

   Programming

   Reconnect the battery. Use the CNH Electronic Service Tool (EST) to program the new module to the vehicle and clear the DCU 19065 / P20C8 fault code.