New Holland DCU 19075 – DCU (Dosing Control Unit): Voltage supply 2 - tube heaters (UB2) electrical | Short circuit to Ground UB2 | P20C3 Reagent - suction tube heating - short circuit low

The system has detected a short circuit to ground on the "UB2" voltage supply circuit. This specific circuit is responsible for powering the heating element in the Diesel Exhaust Fluid (DEF / Reagent) suction tube, which prevents the DEF from freezing in cold temperatures.

• T6 Series (T6.125, T6.140, T6.175, etc.)
• T7 Series (T7.165, T7.170, T7.210, etc.)
• T8 Series (T8.275, T8.320, etc.)
• TS6 Series
• CR Series (CR6090, CR8.90, CR9090)
• CX Series
• LM Series
• TH Series
• Speedrowers

1. 1

   Visually inspect the external wiring harness connecting the DCU to the DEF pump module and the DEF suction tube heater for chafed insulation, melted wires, or pinched harnesses.

2. 2

   Disconnect the electrical connector at the DEF pump module and the suction tube heater. Use a multimeter to check the UB2 circuit for continuity to ground.

3. 3

   If the external wiring harness tests fine (no short to ground), isolate the issue to an internal failure within the DEF pump module's heater circuit.

1. 1

   Turn off machine and disconnect battery

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

2. 2

   Locate DEF pump module

   Locate the DEF pump module (Denoxtronic supply module), typically mounted near the DEF tank.

3. 3

   Drain DEF tank or clamp lines

   Drain the DEF tank below the level of the pump or clamp the DEF supply and return lines to prevent fluid leakage.

4. 4

   Disconnect electrical connectors

   Carefully disconnect the electrical connectors from the DEF pump module.

5. 5

   Disconnect DEF lines

   Disconnect the DEF suction, pressure, and return lines from the module.

6. 6

   Remove faulty DEF pump module

   Unbolt the mounting hardware and remove the faulty DEF pump module.

7. 7

   Install replacement DEF pump module

   Install the replacement DEF pump module and secure the mounting bolts.

8. 8

   Reconnect DEF lines

   Reconnect the DEF lines, ensuring the fittings click into place securely to prevent leaks.

9. 9

   Reconnect electrical connectors and battery

   Reconnect the electrical connectors and the battery.

10. 10

    Program/calibrate new DEF pump module

    Connect a dealer diagnostic tool (such as the CNH Electronic Service Tool - EST). A new DEF pump module must be programmed/calibrated to the vehicle's DCU after replacement.

11. 11

    Clear fault codes and test system

    Clear the fault codes and run a system test or manual DEF dosing test to verify the heater circuit is operating correctly.