Case IH 19264 (DTC 569A) - ECU – DCU (Dosing Control Unit) / Engine ECU (ENG): DEF/AdBlue tank heater actuator open load failure

The control module has detected an "open load" or open circuit in the DEF (Diesel Exhaust Fluid) tank heating valve circuit. This means the ECU is attempting to send voltage to the heater actuator/valve to warm the DEF fluid, but it detects zero current flow. This typically indicates a broken wire, an unplugged connector, a blown fuse/relay, or a burnt-out internal coil within the heater valve itself.

• MAXXUM T4E
• 240 Series Axial-Flow Combines (7240, 8240, 9240)
• 250 Series Axial-Flow Combines (7250, 8250, 9250)
• Magnum Series (235–340 Series 4)
• Steiger Series (350–600)
• Puma Series
• Maxxum Series

1. 1

   Inspect the wiring harness and the electrical connector at the DEF tank heating valve for chafed wires, corrosion, or a disconnected plug.

2. 2

   Check the DEF heater main relay and associated fuses.

3. 3

   Disconnect the DEF tank heater valve and use a multimeter to measure the resistance across the valve's coil pins (an 'OL' reading confirms the internal coil is broken/open).

4. 4

   Ensure the DEF tank coolant hoses are installed correctly, as backward routing can cause continuous hot water circulation and overheat the DEF tank.

1. 1

   Power Down

   Turn off the machine and disconnect the battery ground cable to ensure safety while working on the electrical and emissions systems.

2. 2

   Access the Valve

   Locate the DEF tank heating valve (usually mounted near or integrated into the DEF tank sending unit/head assembly).

3. 3

   Isolate the Fault

   If the wiring harness tested good but the valve failed the resistance test, the valve must be replaced.

4. 4

   Relieve Pressure & Drain

   If replacing an inline coolant control valve for the DEF heater, clamp the coolant lines to prevent fluid loss. If replacing the in-tank heater unit, drain the DEF tank below the level of the heater assembly.

5. 5

   Remove & Replace

   Disconnect the coolant hoses and electrical connector. Remove the mounting hardware and extract the faulty heater valve/actuator. Install the new unit and reconnect the hoses and wiring.

6. 6

   Clear Codes

   Reconnect the battery. Use a diagnostic scan tool (like the Case IH Electronic Service Tool) to clear the error log in the DCU/ECU.

7. 7

   Test Operation

   Start the engine and verify that the fault code does not return and that the DEF system operates normally without triggering an engine derate.