Fault Diagnosis, Troubleshooting, and Emergency Procedures
Fault Diagnosis, Troubleshooting, and Emergency Procedures
This domain tests systematic fault finding and immediate response. Expect questions on hydraulic and electrical symptoms, emergency lowering, fire, hydraulic injection, rollover, and trench collapse.
Core rules
- Diagnose in order: confirm the symptom, check simple causes-fuel, safety lever, pilot enable, fuses, error codes-then test pressures and flows.
- Low hydraulic power: check oil level, filters, pump pressure, relief leakage, and cylinder bypass. Drift points to a load-holding valve.
- Electrical: battery, alternator, fuses, harness, sensors.
- Emergency: fire-shut off engine, evacuate, use the correct extinguisher; hydraulic injection-stop work and get immediate medical care; rollover-stay belted and brace; trench collapse-do not enter, call rescue.
- Utility strike: stop, evacuate, call the utility and emergency services.
- Know emergency lowering and pressure-relief procedures before you need them.
- Report, tag, and repair before returning to service.
Worked example
The machine will not swing, but boom and travel work. Reasoning: the main pump is probably supplying other circuits, so check the swing lock/park brake, pilot enable, swing circuit pressure, motor case drain, and error codes. Isolate the swing circuit and test before adjusting the main relief.
Traps
- Replacing parts without testing.
- Reaching into linkage with the engine running.
- Using water on a fuel fire.
- Entering a collapsed trench to rescue.