Massey Ferguson E4375.03 – ECU: AdBlue™ or DEF pump motor Short circuit to +12 V
Issue description
The controller is detecting voltage on the DEF pump motor control circuit that is higher than expected, indicating a short to battery power.
Applies to these machines
54 machines- 7616
- 5612
- 7622
- Interim Tier 4 (2012-2015)
- 7614
- 5611
- 7615
- 5610
- 5613
- 7620
- 5609
- 7618
- 5608
- 7619
- 7626
- 7624
- MF 4707
- MF 4708
- MF 4709
- MF 4710
- MF 5608
- MF 5609
- MF 5610
- MF 5611
- MF 5612
- MF 5613
- MF 5710 SL
- MF 5711 SL
- MF 5712 SL
- MF 5713 SL
- MF 7614
- MF 7615
- MF 7616
- MF 7618
- MF 7619
- MF 7620
- MF 7622
- MF 7624
- MF 7626
- MF 7714
- MF 7715
- MF 7716
- MF 7716S
- MF 7718
- MF 7718S
- MF 7719
- MF 7720
- MF 7720S
- MF 7722
- MF 7722S
- MF 7724
- MF 7724S
- MF 7726
- MF 7726S
Check the cause
Inspect the DEF pump wiring harness between the ECU and the pump for chafing, melted insulation, or pinched wires that could cause a short to a power wire.
Disconnect the electrical connector at the DEF pump and check for corrosion, bent pins, or DEF fluid intrusion.
With the pump disconnected and the key ON, use a multimeter to check the pump control circuit pins on the harness side for unexpected 12V power.
If the harness tests good (no short to power found), test the DEF pump motor itself as the short is likely internal.
Repair steps
Disconnect Power
Disconnect the tractor's battery to prevent any further electrical damage during the repair.
Repair Wiring
If a short was found in the harness during diagnostics, splice and repair the damaged section of the wire, or replace the DEF pump wiring harness entirely.
Replace the DEF Pump
If the short is internal to the pump: clean the area around the DEF pump, disconnect the fluid lines (have a catch pan ready), unbolt the assembly from its mounting bracket, install the new DEF pump, torque the mounting bolts to OEM spec, and reconnect the fluid lines and electrical connector.
Replace the DEF Filter
It is highly recommended to replace the DEF filter whenever replacing the pump to ensure no crystallized DEF or contaminants damage the new unit.
Clear Codes and Prime
Reconnect the battery. Use a diagnostic scan tool to clear the E4375.03 fault code. Run a system test or prime the DEF system to pressurize the lines and check for leaks.
Parts you might need
(3)DEF Pump / Urea Dosing Module
V837072107Bosch Part Number: 0444023011. Fits various AGCO/Massey Ferguson models. Often sold as a complete dosing module assembly.
DEF Filter
ACP0594170Replaces older part numbers V837091530, V837079723, V837091483
DEF Pump Wiring Harness
Specific part number will vary heavily depending on the exact tractor model and chassis configuration.
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