Case IH 19264 – DCU (Dosing Control Unit): Tank heating Valve | Open load | Reagent - tank heating valve - open circuit

This fault code indicates an electrical "open load" (open circuit) in the DEF (Diesel Exhaust Fluid / Reagent) tank heating valve circuit. The controller is not detecting electrical continuity to the valve's solenoid, which is typically caused by a disconnected plug, a broken wire, or an internally failed solenoid coil.

• Tier 4a
• Tier 4b
• Magnum Series (235-340 Series 4, 310)
• Steiger Series (350-600)
• Puma
• Maxxum
• Axial-Flow 7230
• Axial-Flow 8230
• Axial-Flow 7250

1. 1

   Wiring and Connections: Inspect the wiring harness between the DCU and the DEF tank heating valve. Look for disconnected plugs, corroded pins, or chafed/broken wires.

2. 2

   Coil Resistance Test: Use a multimeter to measure the resistance across the pins of the DEF tank heating valve. If the reading shows infinite resistance (OL), the internal coil is broken, and the valve must be replaced.

3. 3

   Hose Routing Verification: Check the coolant hose routing to the DEF tank. The DEF heater line with the 'red' band must be connected to the top tube running to the front of the engine head.

1. 1

   Preparation

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

2. 2

   Locate the Valve

   Locate the DEF tank heating control valve, which is plumbed inline with the engine coolant hoses leading to the DEF tank.

3. 3

   Isolate the Coolant

   Clamp off the coolant hoses on both sides of the heating valve using hose pinch-off pliers to prevent excessive coolant loss.

4. 4

   Disconnect

   Unplug the electrical harness connector from the valve. Loosen the hose clamps and pull the coolant hoses off the valve fittings.

5. 5

   Removal

   Remove the mounting bolts/hardware securing the valve to its bracket and remove the faulty valve.

6. 6

   Installation

   Install the new valve. Note: The heater control valve is a directional valve. Ensure it is installed in the correct flow direction. If assembled backwards, the valve cannot cut off coolant flow, which will force high-temperature coolant into the DEF tank continuously and cause DEF overheating/derating.

7. 7

   Reassembly

   Reconnect the coolant hoses and tighten the hose clamps. Plug in the electrical connector.

8. 8

   Fluid Check

   Remove the hose clamps. Top off the engine coolant if any was lost, and bleed the cooling system of air if necessary.

9. 9

   Clear Codes

   Reconnect the battery. Use the Case IH Electronic Service Tool (EST) to clear the fault code from the DCU and run a system test to verify the valve actuates properly.