Case IH 17773 (F-5706-16) - ECU – Engine ECU: DEF/AdBlue supply module pump motor Heater Module: duty cycle above maximal limit

This fault code indicates an issue with the heating circuit for the Diesel Exhaust Fluid (DEF) supply module (also known as the DEF pump or doser pump). The 'duty cycle above maximal limit' condition means the Engine ECU is commanding the heater to stay on longer than the maximum allowed threshold, pointing to a failed heating element inside the pump, a faulty temperature sensor, or a wiring issue.

• VESTRUM CVX
• Austoft 9900
• Steiger Series
• Steiger 620
• Steiger 600
• Steiger 580
• Steiger 540
• Steiger 500
• Magnum Series
• Axial-Flow Combines
• Axial-Flow 7240
• Axial-Flow 8240
• Axial-Flow 9240
• Patriot sprayers
• Titan floaters

1. 1

   Inspect the electrical harness and connectors between the Engine ECU and the DEF Supply Module for corrosion, moisture intrusion, or chafed wires.

2. 2

   Use a diagnostic scan tool to monitor the DEF tank temperature and ambient air temperature sensors for plausibility (an artificially low reading will command the heater on continuously).

3. 3

   Disconnect the DEF supply module and measure the resistance of the internal heater circuit pins with a multimeter to check for an open circuit or short.

4. 4

   Verify that the DEF supply module is receiving the correct voltage (12V or 24V) when the heater is commanded on.

1. 1

   Preparation

   Turn off the ignition switch and wait until communication with the diagnostic scan tool is completely discontinued (allow the system to power down and purge).

2. 2

   Drain the DEF

   Place a clean catch pan under the DEF supply module and drain the DEF fluid from the lines.

3. 3

   Disconnect Lines and Wiring

   Carefully disconnect the electrical harness connector from the DEF supply module. Disconnect the DEF suction, return, and pressure hoses. Cap the lines immediately to prevent dirt and debris from entering the SCR system.

4. 4

   Remove the Module

   Unbolt the DEF supply module from its mounting bracket.

5. 5

   Install the New Module

   Mount the replacement DEF supply module. Reconnect the DEF hoses, ensuring they click securely into place. Reconnect the electrical harness.

6. 6

   Filter Replacement

   It is highly recommended to replace the DEF supply module main filter (if not already pre-installed in the new pump) to prevent contamination of the new unit.

7. 7

   Prime and Clear Codes

   Turn the ignition ON without starting the engine. Use a diagnostic scan tool to clear the 17773 (F-5706-16) fault code. Run a DEF system prime/doser test via the scan tool to ensure the system builds pressure and there are no leaks.