Massey Ferguson E4375.05 – Engine Control Unit (ECU): DEF Pump Control Issue (ECU) / AdBlue™ or DEF pump motor Current below normal or open circuit

The controller is detecting a break in the electrical circuit to the DEF pump motor or the current draw is lower than the expected threshold, preventing the pump from operating correctly.

• 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

   Trace the wiring harness from the Engine ECU to the DEF pump. Look for chafed wires, breaks, or rodent damage that would cause an open circuit.

2. 2

   Disconnect the electrical plug at the DEF pump and the ECU. Inspect the pins for corrosion, pushed-out pins, or moisture intrusion (DEF fluid is highly corrosive if it leaks into the connector).

3. 3

   Use a multimeter to check the resistance across the DEF pump motor terminals. An infinite reading (OL) confirms an internal open circuit in the pump motor.

4. 4

   Verify that the pump is receiving the correct voltage from the ECU when commanded on.

1. 1

   Preparation

   Turn off the tractor, remove the key, and disconnect the battery to prevent electrical shorts.

2. 2

   Locate the Pump

   Locate the DEF/AdBlue pump supply module, typically mounted on the chassis near the DEF tank.

3. 3

   Disconnect Lines

   Carefully disconnect the DEF fluid lines from the pump. Note: Have a clean catch pan ready, as DEF fluid will spill. Clean any spilled DEF immediately with warm water to prevent corrosion.

4. 4

   Disconnect Electrical

   Unplug the main electrical harness connector from the DEF pump.

5. 5

   Dismount the Pump

   Unbolt the DEF pump from its bracket. Inspect the rubber vibration isolation mountings; if they are degraded, replace them.

6. 6

   Install New Pump

   Mount the new DEF pump assembly onto the vibration bushings and secure the bolts.

7. 7

   Reconnect

   Reconnect the DEF fluid lines (ensuring they click securely into place) and plug in the electrical connector.

8. 8

   Clear and Test

   Reconnect the battery. Use a dealer diagnostic tool to clear the E4375.05 fault code and initiate a DEF system pressure test/dosing test to prime the pump and verify the repair.