What is XCMG XE750D Fault Code 3372-3 SPN2630 FMI3?

Fault Code 3372-3 (SPN 2630 FMI 3) indicates a voltage above normal or shorted to high source condition in the Diesel Exhaust Fluid (DEF) pump control circuit. This code is triggered when the Engine Control Module (ECM) detects an electrical voltage reading that exceeds the manufacturer's specified parameters in the DEF dosing system.

On the XCMG XE750D excavator, this fault directly affects the Selective Catalytic Reduction (SCR) system, which is critical for meeting emission standards. The DEF pump injects precise amounts of diesel exhaust fluid into the exhaust stream to reduce NOx emissions. When voltage irregularities occur in this circuit, the system cannot properly control DEF injection, potentially causing the machine to enter derate mode or fail emissions compliance. For used excavators operating in regulated environments, this fault can result in immediate operational restrictions.

Common Symptoms

• Check Engine Light (CEL) or Malfunction Indicator Lamp (MIL) illuminated on the instrument cluster
• Engine power derate or reduced performance mode, limiting hydraulic functions and travel speed
• DEF system warning messages displayed on the monitor screen
• Increased exhaust smoke or visible emissions due to improper SCR function
• DEF consumption abnormalities, either excessive use or no consumption at all

Potential Causes

The most common technical causes for this fault on used XCMG XE750D excavators include:

• Damaged or corroded wiring harness between the ECM and DEF pump, particularly at routing points near the exhaust system where heat exposure is constant
• Shorted DEF pump solenoid or internal pump electrical failure causing excessive current draw
• Corroded or loose electrical connectors at the DEF pump, a frequent issue in machines operating in wet or high-humidity environments
• Failed DEF pump relay or damaged circuit protection components in the power distribution system
• Chafed wiring at known rub points near the frame rails or fuel tank mounting brackets on older machines
• ECM internal fault or software calibration issue (less common but possible in high-hour machines)

How to Troubleshoot and Fix Code 3372-3 SPN2630 FMI3

Step 1: Visual Inspection of Wiring and Connectors Begin by thoroughly inspecting the DEF pump wiring harness from the pump to the ECM. On used excavators, check for wire chafing, insulation damage, or corrosion at connector pins. Pay special attention to harness routing near hot exhaust components and moving parts. Disconnect the DEF pump electrical connector and inspect for moisture, corrosion, or bent pins.

Step 2: Electrical Testing with Multimeter Using a digital multimeter (DMM), test the DEF pump control circuit voltage with the key on, engine off. Compare readings to XCMG specifications (typically 12V nominal). Check for short to power by measuring voltage at the pump connector with it disconnected—any voltage present indicates a wiring short. Test circuit resistance between the pump connector and ECM pins to identify open circuits or high resistance caused by corrosion.

Step 3: DEF Pump Component Testing Test the DEF pump solenoid resistance using an ohmmeter (typical range: 3-8 ohms, verify with XCMG specifications). If resistance is out of range or shows infinite resistance, the pump has failed internally. For used machines, also check the pump ground circuit integrity and ensure proper chassis grounding at mounting points.

Step 4: Advanced Diagnostics and Repair Connect XCMG diagnostic software (or compatible J1939 scan tool) to read real-time DEF pump command data and verify ECM output signals. If wiring and pump test properly but the code persists, suspect ECM programming issues or internal ECM failure. Before replacing expensive components on used equipment, consider that harness repairs and connector replacements resolve the majority of these faults.

Disclaimer: This guide provides general troubleshooting information. Always consult the official XCMG service manual for your specific machine serial number and software version. If you lack proper diagnostic equipment or experience with high-voltage electrical systems, consult a certified XCMG technician or qualified heavy equipment mechanic to avoid injury or further damage.