What is Hitachi ZX350LCK-5G Fault Code 14107-2?

Fault Code 14107-2 on the Hitachi ZX350LCK-5G excavator indicates a malfunction in the DEF (Diesel Exhaust Fluid) pump circuit, specifically a short circuit to ground or abnormal electrical resistance detected by the Engine Control Module (ECM). This code is part of Hitachi's emissions control system diagnostics and directly relates to the Selective Catalytic Reduction (SCR) aftertreatment system.

The DEF pump is responsible for injecting precise amounts of urea solution into the exhaust stream to reduce NOx emissions. When the ECM detects voltage irregularities in the pump's control circuit—typically readings below 0.5V or resistance under 10 ohms to ground—it triggers code 14107-2. For the ZX350LCK-5G's Isuzu engine platform, maintaining proper SCR function is critical not only for emissions compliance but also for preventing engine derate modes that severely limit machine productivity.

Common Symptoms

• Amber warning light illuminated on the instrument cluster with DEF system alert
• Engine power derate after approximately 50 operating hours if the fault persists (progressive reduction to 50% power)
• Increased diesel exhaust opacity or visible smoke during operation
• DEF consumption drops to zero or becomes erratic, visible through monitor display
• Intermittent stalling or rough idle conditions, particularly during cold starts

Potential Causes

The most common technical failures causing code 14107-2 on used ZX350LCK-5G machines include:

• Damaged DEF pump wiring harness at known rub points near the exhaust manifold heat shield or along the frame rail behind the fuel tank
• Corroded connector pins at the DEF pump module (C-107 connector), particularly in machines exposed to road salt or coastal environments
• Failed DEF pump internal windings creating direct short to pump housing (common after 6,000+ hours)
• Chafed harness insulation where the SCR wiring passes through the chassis grommet near the right-side track frame
• Moisture intrusion in the ECM harness connector (C-203) causing cross-circuit contamination
• Faulty ECM ground circuit G-104, located on the engine block near the starter motor

How to Troubleshoot and Fix Code 14107-2

Step 1: Visual Inspection Begin with a thorough harness inspection. Disconnect the DEF pump connector (C-107) and examine pins for green corrosion or bent contacts. On used excavators, inspect the entire harness route from pump to ECM, paying special attention to areas where the harness contacts the frame or passes near heat sources. Check for abraded insulation, particularly at the chassis grommet penetration point.

Step 2: Electrical Testing Using a digital multimeter, perform resistance checks with the ignition off and pump disconnected. Measure resistance between DEF pump control wire (typically gray wire at pin 2) and chassis ground—readings below 10,000 ohms indicate a short circuit. Check continuity between pump ground circuit and ECM ground G-104; resistance should be under 1 ohm. Verify supply voltage at the pump connector with ignition on: should read 12-14V on the power supply pin.

Step 3: Component Testing If harness tests pass, measure DEF pump internal resistance across pump terminals—specification is typically 3-5 ohms. Readings outside this range indicate pump failure. For intermittent faults common in high-hour machines, perform a "wiggle test" while monitoring voltage with Hitachi Dr.EX diagnostic software connected. Replace any components showing erratic readings.

Step 4: Verify Repair After addressing wiring or component issues, clear codes using diagnostic software, operate the machine through a complete work cycle, and verify DEF consumption returns to normal (approximately 2-3% of diesel consumption). Recheck for code recurrence after 10 operating hours.

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Disclaimer: This guide provides general diagnostic information. Complex SCR system repairs should be performed by certified technicians with proper Hitachi diagnostic equipment. Always consult the factory service manual for your specific machine serial number and follow all safety protocols when working with electrical systems.