Case IH 19163 – DCU (Dosing Control Unit): Cooling control valve short circuit to UBat or open load | short circuit to battery | P20A3 Vent valve (Reductant Purge Control Valve) - short circuit high

The engine control system has detected an electrical fault in the DEF (Diesel Exhaust Fluid) Coolant Control Valve circuit. Specifically, the circuit is experiencing an "open load" (a broken wire or disconnected component) or a "short circuit to battery" (UBat), which causes the voltage reading on the circuit to be higher than expected.

• Tier 4a
• Case IH Steiger series (350-600 HP)
• Case IH Magnum series (235-340 Series 4)
• Case IH Puma series

1. 1

   Verify if the fault is active or stored (inactive faults may indicate intermittent connections or recent pressure washing)

2. 2

   Inspect the wiring harness running from the DCU to the DEF Coolant Control Valve for chafed wires, melted insulation, or pinched lines

3. 3

   Disconnect the plug at the DEF Coolant Control Valve and check for water intrusion, corrosion, bent pins, or pushed-back terminals

4. 4

   Perform a component resistance test using a multimeter across the pins of the DEF Coolant Control Valve solenoid to check for an open circuit or dead short

5. 5

   With the battery disconnected, perform a harness continuity test on the signal and ground wires from the valve connector back to the DCU harness connector

1. 1

   Preparation

   Turn off the ignition key, allow the engine to cool completely, and disconnect the negative battery cable.

2. 2

   Locate the Valve

   Locate the DEF Coolant Control Valve. It is typically mounted inline with the engine coolant hoses routed toward the DEF tank heater coil.

3. 3

   Clamp the Hoses

   Use hose pinch-off pliers on the coolant lines on both sides of the valve to prevent excessive engine coolant loss.

4. 4

   Disconnect Electrical

   Unplug the electrical harness connector from the valve.

5. 5

   Remove the Valve

   Loosen the hose clamps securing the coolant lines to the valve. Carefully twist and pull the hoses off the valve fittings. Remove any mounting bolts securing the valve bracket to the chassis.

6. 6

   Install the New Valve

   Mount the new DEF Coolant Control Valve. Reconnect the coolant hoses and securely tighten the hose clamps.

7. 7

   Reconnect Electrical

   Plug the electrical harness back into the new valve, ensuring it clicks and locks into place.

8. 8

   Finalize

   Remove the hose pinch-off pliers. Reconnect the negative battery cable.

9. 9

   Coolant Check & Code Clearing

   Top off the engine coolant reservoir if any fluid was lost. Start the engine and let it reach operating temperature. Use the CNH Electronic Service Tool (EST) to clear the fault code, or allow the DCU to run its self-check to move the code from active to historic.