Case IH F-4376-05 - ECU – Engine Control Unit (ECU) or Dosing Control Unit (DCU) / Aftertreatment ECU: DEF/AdBlue reverting valve driver circuit open failure

The reverting valve (internal to the DEF Supply Module) reverses the flow of DEF when the engine is shut down to purge the lines. An open failure (FMI 05) indicates that the control module has detected an open circuit, meaning a broken wire, a disconnected plug, or a burnt-out internal solenoid coil on the reverting valve circuit.

• MAGNUM AFS Connect
• 240 Series Axial-Flow Combines (7240, 8240, 9240)
• 130/230 Series Combines
• Magnum Tractors (180 through 370, AFS Connect)
• Steiger Tractors
• Maxxum Tractors
• Puma Tractors
• Farmall Tractors
• Patriot Series Sprayers (4430)

1. 1

   Inspect the wiring harness running from the ECU/DCU to the DEF Supply Module for chafed wires, rodent damage, or breaks.

2. 2

   Disconnect the main electrical harness at the DEF Supply Module and inspect the pins for corrosion, moisture (DEF intrusion), or pushed-back pins.

3. 3

   Using a multimeter, check the continuity of the reverting valve control circuit wires between the ECU/DCU connector and the DEF pump connector.

4. 4

   Measure the resistance across the reverting valve solenoid pins directly on the DEF Supply Module. If the multimeter reads infinite resistance (OL), the internal coil of the reverting valve has failed.

1. 1

   Power Down

   Turn off the ignition and disconnect the machine's battery to prevent electrical spikes.

2. 2

   Harness Repair

   If the diagnostic checks revealed a broken wire or corroded connector in the machine's harness, repair the wiring or replace the pigtail connector.

3. 3

   Module Replacement

   If the internal coil is open, the entire DEF Supply Module must be replaced. Thoroughly clean the area around the DEF pump. Disconnect the electrical connector. Pinch off or plug the DEF supply/return lines and the engine coolant lines to minimize fluid loss, then disconnect them. Unbolt the DEF Supply Module from its mounting bracket and remove it. Install the new DEF Supply Module and torque the mounting bolts to OEM spec. Reconnect the DEF lines, coolant lines, and electrical connector.

4. 4

   Post-Repair

   Reconnect the battery. Use a diagnostic scan tool to clear the F-4376-05 fault code. Run a DEF system prime/leak test via the scan tool to ensure the system builds pressure and the reverting valve operates correctly upon shutdown.