Cert IV Auto Diagnostic study guide
Cert IV Auto Diagnostic · Work through your exam, one topic at a time.
The Certificate IV in Automotive Mechanical Diagnosis (AUR40216) is an Australian vocational qualification for technicians who already have trade-level mechanical skills and want to specialise in systematic fault finding rather than routine servicing. It suits experienced light-vehicle mechanics moving into diagnostic roles, workshop foremen who sign off complex repairs, and technicians preparing to work on networked electronic systems, driveline faults and climate control. The Cert IV Auto Diagnostic study guide has 8 sections and about 3,213 words.
01Diagnostic Testing and Fault Isolation
Every diagnostic job begins by converting a vague customer complaint into a measurable symptom: when it occurs, under what load, temperature, speed or weather, and whether it is constant or intermittent. Then verify the fault yourself before touching anything.
365 words, about 2 min02Engine and Driveline Systems Diagnosis
The engine needs air, fuel, compression and spark (or injection timing) in the right quantity at the right moment. Diagnosis separates mechanical faults (compression, valve timing, head gasket, worn bearings) from management faults (fuel delivery, ignition, sensors, airflow measurement).
381 words, about 2 min03Electrical and Electronic Systems Diagnosis
Ohm's law and series/parallel circuit behaviour explain almost every electrical fault. Understand that resistance increases with heat, that a voltmeter draws negligible current (so it can read 12 V on a circuit that cannot carry load), and that a test lamp or loaded voltmeter reveals the truth.
365 words, about 2 min04Chassis, Steering, Suspension and Brake Systems Diagnosis
Chassis diagnosis starts at the tyres: pressure, wear patterns, balancing and runout. Uneven wear indicates alignment, inflation or suspension faults.
392 words, about 2 min05Transmission and Drivetrain Systems Diagnosis
Manual gearbox diagnosis covers clutch operation (slip, drag, judder, noise), synchromesh wear, bearing noise and oil leaks. Automatic transmission diagnosis relies on understanding hydraulic pressure, clutch packs, bands, torque converters, valve bodies and electronic control.
348 words, about 2 min06Air Conditioning and Climate Control Diagnosis
Understand the cycle: compressor raises pressure and temperature, condenser rejects heat, expansion device drops pressure, evaporator absorbs heat. Pressure readings on both high and low sides, plus ambient temperature, tell the story.
342 words, about 2 min07Workplace Safety
Workshop hazards include moving machinery, hot surfaces, rotating parts, high voltage (including hybrid and electric vehicles), stored energy in springs and pressurised systems, and chemical exposure. Risk management means identifying the hazard, assessing the risk, controlling it (eliminate, substitute, isolate, engineer, administrate, PPE) and reviewing.
339 words, about 2 min08Environmental and Housekeeping Practices
Workshops generate used oil, filters, coolant, brake fluid, solvents, batteries, tyres and refrigerant. Each must be segregated into labelled containers and consigned through licensed recyclers.
681 words, about 3 min