Case IH 19065 – DCU (Dosing Control Unit): Voltage supply internal heaters 1 (UB1) electrical | Short to bat at UB1 with Key 15 off | P20C8 Pump module - Internal heating - short circuit high

This code indicates an electrical short to the battery (high voltage source) on the UB1 circuit (Voltage supply for internal heaters 1) when the ignition key (Key 15) is turned off. The system has detected an internal short circuit in the internal heating element of the DEF (Diesel Exhaust Fluid) pump module.

• Tier 4a
• Case IH Magnum (235-405 series)
• Case IH Steiger (350-620 series)
• Case IH Rowtrac
• Case IH Farmall
• Case IH Maxxum
• Case IH Puma
• Case IH Optum
• Case IH Axial-Flow 240 Series
• Case IH Axial-Flow 5130-9230 series
• Case IH Axial-Flow 5140-9250 series
• Case IH Patriot (2250, 3240, 3340)
• Case IH Trident 5550

1. 1

   Inspect the wiring harness leading to the DEF pump module for an external short to battery voltage on the UB1 supply pin when the ignition is switched off.

2. 2

   Verify if the short is internal to the pump module's heating circuit by confirming the external wiring is intact and shows no voltage with the key off.

1. 1

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

2. 2

   Locate the DEF Pump Module (Dosing Control Unit) near the DEF tank assembly.

3. 3

   Thoroughly clean the area around the module to ensure no dirt or debris contaminates the DEF lines.

4. 4

   Disconnect the electrical harness connectors from the module.

5. 5

   Disconnect the DEF fluid lines.

   Have a clean catch pan ready to capture any spilled Diesel Exhaust Fluid.

6. 6

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

7. 7

   Install the new DEF pump module and torque the mounting bolts to OEM specifications.

8. 8

   Reconnect the DEF fluid lines and the electrical connectors.

9. 9

   Reconnect the battery.

10. 10

    Program/flash the new DEF module to the vehicle's ECU using the Case IH Electronic Service Tool (EST).

    The system will not function correctly without this software calibration.

11. 11

    Clear the inactive fault codes and run the machine to verify the SCR system operates without derating or throwing new codes.