Massey Ferguson E4375.04 – Engine Control Unit (ECU): DEF Pump Control Issue

The AdBlue™ or DEF pump motor has a short circuit to earth (ground) (-). The control module is detecting an abnormal drop in voltage on the DEF pump motor circuit, typically caused by a damaged wire touching the chassis or an internal short within the pump motor itself.

• 7616
• 5612
• 7622
• Interim Tier 4 (2012-2015)
• 7614
• 5611
• 7615
• 5610
• 5613
• 7620
• 5609
• 7618
• 5608
• 7619
• 7626
• 7624
• MF 5608
• MF 5609
• MF 5610
• MF 5611
• MF 5612
• MF 5613
• MF 7614
• MF 7615
• MF 7616
• MF 7618
• MF 7619
• MF 7620
• MF 7622
• MF 7624
• MF 7626

1. 1

   Visually inspect the wiring harness running from the ECU to the DEF pump (Bosch Denoxtronic supply module) for chafed insulation, pinched wires, or areas rubbing against the tractor frame.

2. 2

   Disconnect the electrical connector at the DEF pump and use a multimeter to check for continuity to ground on the power supply pins of the harness. Continuity to ground indicates a wiring harness fault.

3. 3

   Check the internal resistance of the DEF pump motor pins. A reading of zero or near-zero ohms indicates an internal short circuit within the pump motor.

4. 4

   Inspect the DEF module and dosing lines for crystallized urea deposits or blockages, which can overwork the pump and lead to premature electrical failure.

1. 1

   Disconnect Power

   Turn off the tractor and disconnect the negative battery terminal to prevent electrical spikes.

2. 2

   Repair Wiring

   If the diagnostic tests revealed a short in the wiring harness, locate the damaged section, splice in new wire using weather-sealed heat-shrink connectors, and re-loom the harness away from sharp edges.

3. 3

   Replace the DEF Pump

   If internally shorted, relieve any residual pressure in the DEF lines. Disconnect the electrical harness and the DEF fluid lines from the supply module. Unbolt the defective DEF pump/supply module from its mounting bracket. Install the new DEF pump and torque the mounting bolts to OEM specifications. Reconnect the fluid lines, ensuring the O-rings are seated correctly to prevent leaks, and reconnect the electrical harness.

4. 4

   Replace the AdBlue Filter

   Replace the AdBlue filter and inspect the filter cover to ensure no contaminants enter the new module.

5. 5

   System Prime and Clear Codes

   Reconnect the battery. Turn the key to the ON position to allow the system to prime. Use a diagnostic scan tool to clear the E4375.04 fault code from the ECU and perform a forced SCR system test to verify pump pressure and dosing operation.