New Holland DCU 19083 – DCU: Voltage supply 3 - Coolant control valve and reverting valve (UB3) electrical | Open circuit to UB3 | P20A0 Vent valve (Reductant Purge Control Valve) - open circuit

An electrical open circuit in the voltage supply line (UB3) that powers the DEF system's coolant control valve and reverting valve, which regulates the flow of hot engine coolant to the DEF tank and lines.

• T5
• T6
• T7
• T8
• T9
• CR9090
• CX8080
• CX8090
• LM6.32
• LM6.35
• LM7.35
• W190C
• W230C

1. 1

   Inspect the wiring harness between the DCU and the Coolant Control Valve / DEF Supply Module for disconnected plugs, chafed wires, or corroded pins.

2. 2

   Test the electrical resistance of the Coolant Control Valve coil; an infinite reading indicates an internal open circuit in the valve itself.

3. 3

   Ensure the Coolant Control Valve is not mechanically stuck open or closed by checking if the coolant lines are warm up to the DEF tank level unit when they should not be.

4. 4

   Verify that the main supply module connector is fully seated, as the reverting valve is often integrated into or mounted alongside the DEF supply module.

1. 1

   Access the Valve

   Locate the Coolant Control Valve. On many New Holland machines, it is attached to the support structure of the Diesel Oxidation Catalyst (DOC) alongside the DEF supply module.

2. 2

   Disconnect Electrical and Fluid Lines

   Disconnect the electrical harness connector from the coolant control valve. Clamp off the coolant hoses to prevent excessive fluid loss, then disconnect the hydraulic/coolant lines from the valve.

3. 3

   Remove the Valve

   Remove the retaining bolts (usually M14 or M6 depending on the bracket) that secure the coolant control valve support bracket.

4. 4

   Install the New Valve

   Mount the replacement valve to the support structure and torque the retaining bolts to spec (e.g., 99 - 108 N·m for M14 bracket bolts).

5. 5

   Reconnect

   Reattach the coolant lines and remove the hose clamps. Plug the electrical connector back into the valve.

6. 6

   Clear Codes and Test

   Use the Electronic Service Tool (EST) to clear the DCU 19083 and P20A0 fault codes. Run the machine and observe if the code resets or if secondary codes (like P20C9) appear, which would indicate a deeper issue within the DEF supply module. Top off any lost engine coolant.