Case IH 19064 – DCU: Voltage supply internal heaters 1 (UB1) electrical | Open circuit to UB1 | P20C5 Pump module - Internal heating - open circuit.

This code indicates an electrical open circuit in the internal heating element (Heater 1 / UB1) of the DEF (Diesel Exhaust Fluid) Pump Module (also known as the Supply Module). The internal heater is designed to thaw DEF in cold weather to prevent the pump from freezing. An "open circuit" means there is a break in the electrical path—most commonly a burned-out heating element inside the pump, a severed wire, or a disconnected plug.

• Tier 4a
• Tier 4b
• Steiger 350
• Steiger 400
• Steiger 450
• Steiger 500
• Steiger 550
• Steiger 600
• Magnum 180
• Magnum 200
• Magnum 220
• Magnum 235
• Magnum 240
• Magnum 250
• Magnum 290
• Magnum 340
• Puma 150
• Puma 165
• Puma 175
• Puma 185
• Puma 200
• Maxxum 115
• Maxxum 125
• Maxxum 135
• Maxxum 145
• Farmall 120A
• Farmall 130A
• Farmall 140A
• Axial-Flow 5130
• Axial-Flow 6130
• Axial-Flow 7130
• Axial-Flow 7230
• Axial-Flow 8230
• Axial-Flow 9230
• Axial-Flow 5140
• Axial-Flow 6140
• Axial-Flow 7140
• Axial-Flow 7240
• Axial-Flow 8240
• Axial-Flow 9240
• Patriot 2250
• Patriot 3240
• Patriot 3340
• Trident 5550

1. 1

   Visual Inspection: Inspect the wiring harness and connectors between the DCU and the DEF Pump Module for any signs of chafing, corrosion, or disconnected pins.

2. 2

   Circuit Continuity Test: Disconnect the electrical harness at the DEF pump. Use a multimeter to check the resistance (Ohms) across the pins for the internal heater on the pump side. If the multimeter reads infinite resistance (OL), the internal heater is broken/open, and the pump module must be replaced.

3. 3

   Voltage Supply Check: Turn the key ON and use a multimeter on the harness side to verify that the DCU is sending the correct voltage to the UB1 circuit when the heater is commanded on.

4. 4

   Fuse/Relay Check: Verify that all fuses and relays providing power to the DEF dosing system and DCU are intact.

1. 1

   Prep the Machine

   Turn off the machine, remove the key, and disconnect the battery to prevent electrical shorts or accidental DCU damage.

2. 2

   Access the Pump

   Locate the DEF Pump Module (usually mounted near or on the DEF tank).

3. 3

   Disconnect Lines

   Carefully disconnect the DEF fluid supply and return lines from the pump. Note: Have a catch pan ready, and ensure the DEF fluid is clean and free from contamination to protect the new module.

4. 4

   Disconnect Electrical

   Unplug the main electrical harness connector from the pump module.

5. 5

   Remove the Pump

   Unbolt the mounting hardware securing the DEF pump module to its bracket or the tank flange, and remove the faulty unit.

6. 6

   Install the New Pump

   Mount the new DEF pump module and tighten the bolts. Reconnect the DEF fluid lines and the electrical harness.

7. 7

   System Prime and Calibration

   Reconnect the battery. Crucial Step: The new module will likely need to be programmed/calibrated to the vehicle's DCU using the Case IH Electronic Service Tool (EST).

8. 8

   Clear Codes

   Use the EST to clear the 19064 / P20C5 fault codes and run a system test to ensure the heater circuit is functioning properly.