New Holland DCU 19073 – DCU (Dosing Control Unit): Voltage supply 2 -tube heaters (UB2) electrical | Short to bat at UB2 with Key 15 off | P20C4 Reagent -suction tube heating -short circuit high

The DEF (Diesel Exhaust Fluid) / Reagent suction tube heating circuit is experiencing a short circuit to battery voltage when the ignition key (Key 15) is turned off. The system detects voltage on the UB2 circuit when it should be completely unpowered.

• T6 series
• T6.160
• T7 series
• T7.165
• T7.220
• T7.270
• T8 series
• TS6 series
• CR series
• CR9090
• CX Elevation series
• CX8080
• CX8090

1. 1

   Inspect the wiring harness between the DEF pump module and the DEF suction tube heater for chafing, melting, or pinched wires that could cause a physical short to battery voltage.

2. 2

   Disconnect the DEF suction tube heater to isolate the circuit. Check if the short to battery voltage persists on the UB2 circuit at the module side.

3. 3

   Inspect the Denox/DEF pump module connector for corrosion, water ingress, or bent pins that could bridge power to the UB2 pin.

4. 4

   If external wiring and connectors are intact, verify if the fault is an internal failure of the DEF pump module (as stated by OEM documentation for this specific Key 15 off condition).

1. 1

   Turn off the machine and remove the key

   Ensure the system is powered down (Key 15 off).

2. 2

   Locate the DEF/Denox pump module

   Trace the suction tube heater wiring.

3. 3

   Perform a visual and multimeter inspection of the wiring harness

   Repair any damaged wiring if an external short is found.

4. 4

   Determine if the fault is internal

   If the wiring tests good, the fault is an internal short within the DEF pump module's heating control circuit.

5. 5

   Remove the DEF lines and electrical connectors

   Disconnect them from the DEF pump module.

6. 6

   Unbolt and remove the faulty DEF pump module

7. 7

   Install the replacement DEF pump module

   Install the Denoxtronic supply module.

8. 8

   Program/calibrate the new module

   The new module will likely need to be programmed/calibrated to the vehicle's ECU using a dealer diagnostic tool (e.g., CNH EST).

9. 9

   Clear the fault codes

   Cycle the key to verify the code does not return.