Case IH F-5435-06 - ECU – Engine Control Unit (ECU): DEF/AdBlue supply module pump motor ECU driver over temperature failure

The Engine Control Unit (ECU) monitoring system has detected an over-temperature condition on the driver circuit that powers the DEF (Diesel Exhaust Fluid) supply module pump motor. This typically indicates a short circuit, excessive electrical resistance, or a failed internal pump motor drawing too much current.

• MAGNUM AFS Connect
• Austoft 9900 Sugar Cane Harvester
• Magnum
• Steiger
• Puma
• Maxxum

1. 1

   Verify if the fault is currently active. If inactive, clear the error log and restart the ECU to see if it returns during the next driving cycle.

2. 2

   Check the wiring of the DEF supply pump (circuit A-030) for a short circuit to battery power.

3. 3

   Disconnect connector X-028C1 and X-190 at the DEF module and inspect the contact surfaces of the pins for oxidation, corrosion, or melting.

4. 4

   Check the DEF supply module heater relay wiring and test operation with a known good relay.

5. 5

   Plug in a test/known-good DEF supply module to see if the over-temperature fault clears, which confirms the original module's internal motor driver has failed.

1. 1

   Preparation

   Turn off the ignition switch and disconnect the battery. Ensure the surrounding area around the DEF tank and pump is completely clean of dried white urea crust and dust before opening any lines to safeguard the internal high-pressure fluid loops.

2. 2

   Removal

   Disconnect the 12-cavity electrical connector from the DEF Supply Module. Disconnect the DEF suction and pressure lines. Unbolt the supply module from its mounting bracket.

3. 3

   Installation

   Install the replacement DEF supply module / dosing pump. Reconnect the fluid lines and the electrical harness.

4. 4

   System Reset

   Reconnect the battery and turn on the ignition. Use a diagnostic scan tool to clear the error log and restart the ECU.

5. 5

   Verification Test

   Execute the SCR fault repair verification test (UDLC - Urea Dosing Leak Check). Using the diagnostic tool, run the test for ~4 minutes. The system pressure should stay at 9000 mbar and the Duty Cycle should stay under 20%. This confirms the pump is operating correctly and clears the derate.