Automotive Servicing NC II key terms

A workplace organization system using five steps: seiri (sort), seiton (set in order), seiso (shine), seiketsu (standardize), and shitsuke (sustain). It keeps automotive work areas clean, tools findable, and hazards visible.

Personal protective equipment such as safety goggles, gloves, coveralls, and steel-toe boots worn to reduce injury risk. In automotive work it also includes face shields for grinding and ear protection when using air tools.

A safety procedure that isolates energy sources before maintenance. A lock and tag on a breaker or disconnect prevent accidental startup of equipment such as a lift, compressor, or engine-driven tool while someone is working on it.

Material Safety Data Sheet, now usually called Safety Data Sheet. It lists a chemical's hazards, safe handling, storage, first-aid, and spill response. Candidates should know where SDS binders sit and how to read sections for fuels, solvents, and coolants.

The routine of keeping floors dry, aisles clear, spills wiped, and waste segregated after every job. Good housekeeping prevents slips, fires, and lost tools, and is assessed during practical workplace inspections.

Recording inspection findings, repairs done, parts replaced, and recommendations in clear, factual language. A good report states the complaint, cause, action taken, and measurements, so the next technician or the customer can act on it.

The written work authorization listing the customer complaint, vehicle details, approved tasks, and parts. Technicians confirm scope before starting and note additional faults for approval rather than doing unrequested work.

A wrench that clicks, beeps, or deflects a dial when a set tightening force is reached. Used wherever a specification is given, such as cylinder heads, wheel nuts, and suspension bolts, to avoid under- or over-tightening.

The manufacturer's stated tightening force for a fastener, often given as a value plus a sequence and sometimes an angle. Following it prevents gasket leaks, stretched bolts, and loosened wheels.

A precision measuring instrument with a calibrated screw and thimble, used for outside diameters, thickness, and wear on shafts, brake discs, and valve stems. It typically reads to 0.01 mm and must be zeroed before use.

A sliding measuring tool with inside, outside, and depth jaws. The vernier or digital scale lets it read to 0.02 mm or 0.01 mm, making it useful for quick checks of bore, disc thickness, and shaft diameter.

A set of thin metal blades of known thickness used to measure gaps such as valve clearance, spark plug gap, and piston ring end gap. The correct gap is the largest blade that fits with slight drag.

A gauge with a spring-loaded plunger and needle dial that shows small linear movement. It is used with a magnetic base to check shaft runout, brake disc lateral runout, gear backlash, and flywheel flatness.

An electrical test instrument measuring voltage, resistance, and current, often with continuity and diode modes. It is the basic tool for tracing open circuits, checking battery voltage, and testing sensors and grounds.

A diagnostic device that connects to the vehicle's diagnostic port to read fault codes, live data, and freeze-frame information, and sometimes to run actuator tests. It guides fault isolation but does not replace circuit testing.

Diagnostic trouble code, a stored identifier set when the control module detects a fault in a monitored circuit or system. The code points to a circuit or system, not automatically to the failed component.

Measuring the voltage lost across a connection, cable, or ground while current flows. A high reading means excessive resistance. It is more reliable than a simple resistance check for finding corroded battery cables and ground straps.

A tool that measures the specific gravity of battery electrolyte to estimate state of charge and detect a weak cell. It applies only to serviceable flooded batteries, not sealed maintenance-free or AGM types.

An engine-driven generator that produces alternating current, rectifies it to direct current, and charges the battery while supplying vehicle loads. Its output is regulated to about 13.5 to 14.5 volts.

A high-torque electric motor that cranks the engine using battery power through a solenoid and pinion drive. Common faults include a worn pinion, burned brushes, and a faulty solenoid contact.

The return path for current, usually through the vehicle body and engine block to the battery negative terminal. Loose or corroded ground points cause dim lights, slow cranking, and erratic sensor readings.

The specified gap between the valve stem and rocker arm or cam follower. Too little clearance can hold a valve open and burn it; too much causes noise and reduced lift. It is set with a feeler gauge when cold or hot as specified.

A toothed belt that synchronizes the crankshaft and camshaft so valves open at the correct moment relative to piston position. It has a replacement interval, and failure on an interference engine can cause severe valve and piston damage.

A mixture of water and antifreeze, usually ethylene glycol or propylene glycol, that carries heat from the engine to the radiator. It also raises boiling point, lowers freezing point, and contains corrosion inhibitors that deplete over time.

A temperature-controlled valve in the cooling circuit that stays closed while the engine warms and opens near operating temperature to allow coolant flow to the radiator. A stuck-open unit causes slow warm-up; a stuck-closed one causes overheating.

A cap with a spring-loaded valve that raises the cooling system pressure above atmospheric, increasing coolant boiling point. It also releases pressure to the overflow when hot and allows coolant to return as the system cools.

A measure of an oil's resistance to flow, expressed in grades such as 10W-30 or 5W-40. The first number describes cold-flow behavior and the second describes thickness at operating temperature.

A replaceable cartridge or spin-on canister that traps metal particles, sludge, and contaminants before oil reaches bearings and passages. Many have a bypass valve so oil still flows if the element clogs.

An instrument that displays the pressure of oil in the lubrication system, either directly or through a sender. Low readings at operating speed can indicate a worn pump, blocked pickup, diluted oil, or excessive bearing clearance.

A system that delivers atomized fuel under pressure into the intake port or directly into the cylinder, metered by an electronic control unit. It replaces the carburetor and gives more precise air-fuel control.

An electrically operated valve that sprays a precise amount of fuel when pulsed by the control module. Clogged or leaking injectors cause misfires, rough idle, and poor fuel economy.

A device that maintains a set fuel pressure in the rail or circuit by returning excess fuel to the tank or by varying pump output. Faulty regulation causes rich or lean running and hard starting.

A friction material bonded to a steel backing plate that presses against the brake disc to slow the wheel. Pads wear over time and must be replaced before the friction material or wear indicator reaches its limit.

The rotating metal rotor clamped by the brake pads in a disc brake system. It must meet a minimum thickness and runout limit; scoring, cracks, or excessive lateral runout cause vibration and poor braking.

A hydraulic fluid, usually glycol-based with a DOT rating, that transmits pedal force to the wheel cylinders or calipers. It absorbs moisture over time, lowering its boiling point, so it is replaced at specified intervals.

Removing trapped air from the hydraulic brake circuit by opening a bleeder screw while an assistant holds and releases the pedal, or by using a pressure or vacuum bleeder. Air makes the pedal feel spongy and reduces braking force.

Adjusting suspension angles, mainly camber, caster, and toe, so the wheels point correctly relative to the vehicle and road. Correct alignment reduces tire wear and improves steering stability.

The amount by which the front of the wheels point toward each other relative to the rear, expressed in millimeters or degrees. Too much causes feather-edge tire wear; too little or toe-out causes inner-edge wear and wandering.

The inward or outward tilt of the top of a wheel from vertical, viewed from the front. Excessive camber wears one tire edge and affects cornering grip, so it is set to the manufacturer's specification.

The forward or rearward tilt of the steering axis, viewed from the side, which affects straight-line stability and steering effort. It is not a tire-wearing angle but a handling angle.

The amount of sideways or radial wobble of a rotating part as it turns, measured with a dial indicator. Excessive runout on a brake disc, hub, or shaft causes vibration and uneven wear.

A friction assembly that connects and disconnects engine power from the transmission, allowing smooth starts and gear changes. It consists of a pressure plate, friction disc, and release bearing.

The small clearance between the release bearing and pressure plate fingers, felt as pedal travel before resistance. Too little causes slippage; too much causes incomplete release and difficult shifting.

A gearbox that changes the ratio between engine speed and wheel speed to match load and road conditions. Manual units use synchronizers and selectors; automatic units use planetary gears and hydraulic control.

A gear assembly that lets the driven wheels turn at different speeds during turns while still transmitting power. It also provides the final drive reduction, and limited-slip versions add clutch packs or gears.