What is Yanmar DX75-9C Fault Code E000108-04?

Fault Code E000108-04 on the Yanmar DX75-9C indicates a low voltage condition on the Engine Control Module (ECM) power supply circuit — specifically a voltage below the acceptable threshold detected on the main ECM supply line (Circuit 108), classified as a "04" failure mode, meaning voltage out of range low.

This code is part of Yanmar's SAE J1939-based diagnostic framework. The ECM is the brain of the engine management system, controlling fuel injection timing, emissions compliance, and hydraulic pump communication. When supply voltage drops below specification, the ECM cannot reliably execute commands — making this fault a high-priority issue that must be addressed immediately.

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Common Symptoms

When Fault Code E000108-04 is active on your Yanmar DX75-9C, operators typically experience:

• Warning light illuminated on the monitor panel (engine caution or red stop lamp)
• Engine derate or power reduction — the machine enters limp mode, limiting RPM and hydraulic output
• Intermittent or hard starting conditions, especially in cold environments
• Erratic or unresponsive throttle behavior from the dial or lever
• Loss of communication between the ECM and other control units, potentially triggering secondary fault codes

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Potential Causes

The following are the most likely technical causes of this fault, particularly on used or high-hour machines:

• Low or failing battery voltage — batteries on used excavators often show surface charge but fail under load
• Corroded or loose battery terminal connections, reducing effective voltage at the ECM
• Damaged or chafed main power harness — on the DX75-9C, the harness routing near the swing frame and bulkhead is a known friction wear point
• Faulty main relay or fusible link in the engine power supply circuit
• Poor ground connections at the ECM ground stud or chassis ground points
• Failing alternator not maintaining adequate charge voltage under load

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How to Troubleshoot and Fix Code E000108-04

Step 1 — Verify Battery and Charging System Using a digital multimeter, measure battery voltage at rest (should be ≥12.6V) and under crank load (should not drop below 9.6V). With the engine running, verify alternator output at 13.8–14.5V DC. Replace or load-test batteries that fail these checks.

Step 2 — Inspect All Power and Ground Connections On used excavators, corrosion and connector fatigue are primary culprits. Physically inspect and clean the battery terminals, main fuse box connections, and the ECM ground stud located on the engine block. Use electrical contact cleaner and dielectric grease on all connectors.

Step 3 — Trace and Inspect the Main ECM Power Harness Follow the main harness from the battery junction block to the ECM connector. Pay close attention to harness routing near the bulkhead grommet and swing frame — areas where chafing is common on this model. Use your multimeter to perform a voltage drop test across the supply circuit; a drop exceeding 0.5V indicates resistance from damage or corrosion.

Step 4 — Inspect the Main Power Relay Swap or bench-test the main ECM relay. A relay with worn contacts can cause intermittent low-voltage events without fully failing.

Step 5 — Connect Diagnostic Software Use Yanmar SmartAssist or a compatible J1939 diagnostic tool to confirm the fault is active, check freeze-frame data, and clear codes after repairs to verify the fix.

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Disclaimer: This guide is intended for informational purposes and general diagnostic direction. Always consult a certified Yanmar technician or authorized dealer for final diagnosis and repair, especially when ECM replacement or advanced electrical work is required. Improper repairs may void warranties or cause further machine damage.