Case IH F-5435-03 - ECU – Engine Control Unit (ECU) or Dosing Control Unit (DCU): DEF/AdBlue supply module pump motor short circuit to battery failure.

The control circuit providing power to the pump motor inside the Diesel Exhaust Fluid (DEF) supply module is experiencing a short to a high voltage source (battery voltage).

• MAGNUM AFS Connect
• Magnum series (180 to 370)
• Steiger series (350 to 600)
• Maxxum series (110 to 140)
• Puma series (130 to 215)
• Axial-Flow 230 and 240 series (5130, 6130, 7130, 7230, 8230, 9230)
• Patriot (4430)
• Titan series
• Farmlift series
• 621F wheel loaders
• 9900 Sugar Cane Harvesters

1. 1

   Check for related active codes (such as DTC 833A). F-5435-03 must be diagnosed and resolved first before addressing over-temperature faults.

2. 2

   Turn OFF the ignition switch until communication with the diagnostic scan tool is discontinued.

3. 3

   Disconnect the wire harness from the DEF/AdBlue Supply Module and inspect the control circuit wiring between the ECU and the module for chafing, melted insulation, or pinched wires.

4. 4

   Use a multimeter to test the pump motor supply pins on the harness side for unexpected battery voltage when the circuit should be unpowered or grounded.

1. 1

   Turn OFF the ignition switch and disconnect the battery ground if performing electrical repairs.

2. 2

   If the diagnostic pin testing reveals a wiring short in the chassis harness, locate the damaged section of the harness and repair the wires, or replace the affected harness section.

3. 3

   If the wiring harness tests good, the short circuit is internal to the pump motor within the DEF Supply Module.

4. 4

   To replace the module: Tag and disconnect the wire harness and the DEF fluid lines from the DEF/AdBlue Supply Module.

5. 5

   Unbolt the module from its mounting bracket (often located near the DEF storage tank).

6. 6

   Install the new DEF Supply Module and reconnect the fluid lines and electrical harness.

7. 7

   Turn ON the ignition switch without starting the engine.

8. 8

   Use a diagnostic scan tool to clear the F-5435-03 fault code and run a DEF system leak/dosing test to verify the repair.