Case IH 17774 (F-5706-18) - ECU – Engine Control Unit (ECU): Engine heater module of the DEF/AdBlue feed module: duty cycle below the minimum limit.

This fault indicates that the Engine Control Unit (ECU) has detected that the electrical duty cycle (PWM signal) for the DEF/AdBlue supply module's internal heater has fallen below the minimum allowable threshold. This typically points to an open circuit, high resistance in the heater circuit, or a failed internal heater within the DEF supply pump module, preventing the system from properly thawing or maintaining the temperature of the diesel exhaust fluid.

• VESTRUM CVX
• Austoft 9900 Sugarcane Harvesters
• Axial-Flow 240 Series
• Axial-Flow 5130-9230
• Axial-Flow 5140-9240
• Axial-Flow 7250
• Axial-Flow 8250
• Axial-Flow 9250
• Magnum (180-370)
• Steiger (350-600)
• Maxxum
• Puma
• T8/T9 series equivalents
• Patriot 4430
• Trident 5550
• Titan Floaters

1. 1

   Inspect the wiring harness leading to the DEF supply module for chafed wires, corroded pins, or loose connections that could cause high resistance or an open circuit.

2. 2

   Verify that the DEF supply module is receiving proper voltage and has a solid ground connection from the ECU.

3. 3

   Pin out the heater circuit on the DEF module to check for an internal open circuit (infinite resistance).

4. 4

   Ensure the DEF fluid is clean and not contaminated, as contamination can damage the pump and its internal components.

1. 1

   Preparation

   Turn off the machine, disconnect the battery to prevent electrical shorts, and ensure the exhaust/SCR system has cooled down.

2. 2

   Locate the Module

   Locate the DEF/AdBlue supply module. On many Case IH machines, it is attached to the side of the fuel tank or mounted inside a protective tool box near the DEF tank.

3. 3

   Disconnect Lines

   Carefully disconnect the DEF supply, return, and pressure lines. Note: DEF can be corrosive to certain metals and wiring; clean up any spills immediately with warm water.

4. 4

   Disconnect Electrical

   Unplug the main electrical harness connector from the module.

5. 5

   Remove the Module

   Remove the mounting bolts securing the pump module to its bracket and remove the unit.

6. 6

   Install New Module

   Mount the replacement DEF supply module and tighten the bolts to OEM torque specs.

7. 7

   Reconnect

   Reconnect the DEF fluid lines (ensure they click/lock into place) and plug in the electrical harness.

8. 8

   Filter Replacement

   It is highly recommended to replace the DEF supply filter (if not already pre-installed in the new unit) whenever replacing the pump.

9. 9

   Programming/Calibration

   The new Bosch DEF dosing/supply module will likely need to be programmed or calibrated to the vehicle's ECU using the Case IH EST (Electronic Service Tool) diagnostic software so the ECU recognizes the new pump.

10. 10

    Clear Codes and Test

    Reconnect the battery, clear the 17774 (F-5706-18) fault code, and run the engine to verify that the SCR system builds pressure and no leaks are present.