Maharashtra HSC NSQF Automotive Service Technician (G3) cheat sheet

Fire classes for workshop use: Class A solid combustibles (water/foam), Class B flammable liquids such as petrol and diesel (foam, dry powder, CO2), Class C flammable gases (dry powder), Class D metal fires such as magnesium (dry powder only, never water), and electrical fires (CO2 or dry powder, never water).

A vehicle must be raised on a trolley jack only for lifting; axle stands rated for the load are placed under the manufacturer's jacking points before any part of the body goes under the vehicle.

Compressed-air blowguns are limited to about 2 bar (30 psi) at the nozzle for cleaning; air must never be directed at skin, and eye protection plus a chip guard is used.

Battery charging releases hydrogen, which is explosive between roughly 4% and 75% by volume in air; charging areas need ventilation, no open flame, and no spark-producing tools near the vents.

Exhaust gas carbon monoxide is odourless and binds haemoglobin about 200-250 times more strongly than oxygen; engines are never run in a closed bay without extraction.

COSHH-style hierarchy of control: eliminate the hazard, substitute, use engineering controls (extraction, guards), then administrative controls, and personal protective equipment last.

5S sequence: Seiri (sort), Seiton (set in order), Seiso (shine), Seiketsu (standardise), Shitsuke (sustain); a red-tag area holds items awaiting disposal decision.

Waste segregation in the workshop: used engine oil and filters, coolant, brake fluid, solvents, and lead-acid batteries are hazardous streams kept separate from general scrap; spill kits use absorbent granules, not washing into drains.

Lockout/tagout before working on a vehicle or machine: isolate the energy source, apply a personal lock and tag, verify zero energy, and only the person who applied the lock removes it.

Micrometer least count = pitch of spindle thread / number of divisions on the thimble; a 0.5 mm pitch screw with a 50-division thimble gives 0.01 mm.

Vernier calliper least count = smallest main-scale division / number of vernier divisions; a 1 mm main division with 50 vernier divisions gives 0.02 mm.

Vernier height gauge and depth gauge share the same least-count principle as the calliper; the reading is main scale before the vernier zero plus the coinciding vernier division times the least count.

Dial gauge (plunger type) reads in 0.01 mm or 0.001 mm; it is used for runout, end play, and shaft bend, and must be mounted rigidly with the plunger perpendicular to the measured surface.

Torque wrench accuracy is typically within plus or minus 4% of indicated value; it is used to tighten, not to loosen, and is returned to its lowest setting after use.

Feeler gauge (thickness gauge) blades are used for valve clearance, spark plug gap, and ring end gap; the correct clearance is the largest blade that enters with slight drag.

Bore gauge (dial or telescopic) measures cylinder bore and taper; the gauge is first zeroed against a micrometer at the nominal bore size.

Six-point sockets contact the flats of a fastener, giving better grip than 12-point sockets; a torque multiplier or breaker bar extends leverage but not the torque setting on the wrench.

Compression tester, vacuum gauge, timing light, and multimeter are diagnostic instruments; a cylinder leakage tester locates where compression is lost (rings, valves, head gasket).

Four-stroke cycle order: intake, compression, power (expansion), exhaust, with two crankshaft revolutions per cycle and one power stroke per cylinder per two revolutions.

Compression ratio = (swept volume + clearance volume) / clearance volume; petrol engines commonly run about 9:1 to 12:1, diesel about 16:1 to 22:1.

Engine displacement = cylinder area x stroke x number of cylinders; bore and stroke in the same unit, result converted to cc.

Valve clearance is measured with the engine cold (or hot per specification) between cam lobe base circle and tappet; too little clearance causes valve burning, too much causes noise and reduced lift.

Firing order is set by crankshaft and camshaft design; a 4-cylinder inline engine commonly fires 1-3-4-2 and a 6-cylinder inline 1-5-3-6-2-4.

Diesel compression ignition needs high compression plus fuel injected near the end of compression; a glow plug aids cold starting, not continuous running.

Cooling system: thermostat opens at a rated temperature (often around 82-90 degrees C), radiator cap maintains about 0.9-1.1 bar, raising boiling point by roughly 20 degrees C.

Lubrication: oil pump draws from sump, passes through filter, then to main gallery, crankshaft drillings, camshaft, and valve train; oil pressure warning switch typically triggers below about 0.3-0.5 bar.

Timing belt or chain drives the camshaft at half crankshaft speed in a four-stroke engine; a broken belt on an interference engine causes valve-to-piston contact.

Manual gearbox gear ratio = driven gear teeth / driving gear teeth; overall ratio is gearbox ratio times final drive ratio.

Clutch transmits torque by friction between flywheel, clutch disc, and pressure plate; free play at the pedal is typically 10-25 mm and must allow the release bearing to clear.

Torque converter in an automatic transmission multiplies torque at stall via the stator; a lock-up clutch bypasses the fluid coupling at cruising speed for efficiency.

CV joints: outer joint is usually a Rzeppa fixed joint allowing steering angle; inner joint is a plunge type (tripod or double-offset) allowing suspension travel.

Wheel alignment angles: camber is the inward or outward tilt in front view, caster is the steering axis tilt in side view, toe is the difference in distance between front and rear of the wheels.

Ackermann principle: inner wheel turns at a sharper angle than the outer wheel so all wheels roll about a common centre during a turn.

Power steering: hydraulic type uses an engine-driven pump and rotary valve; electric power steering (EPS) uses a motor on the column or rack and an ECU with torque sensor input.

Suspension types: MacPherson strut combines spring and damper in one unit with the upper mount as a pivot; double wishbone uses upper and lower control arms; leaf springs are used on many light commercial vehicles.

Tyre marking 195/65 R15: 195 mm section width, 65 aspect ratio (sidewall height = 65% of 195 mm), R radial construction, 15 inch rim diameter.

Ohm's law V = I x R; power P = V x I = I squared x R = V squared / R; a 12 V circuit drawing 5 A has 2.4 ohm resistance and 60 W power.

Series circuit: same current through all elements, voltages add; parallel circuit: same voltage across all branches, currents add.

Lead-acid cell nominal voltage is 2.1 V; a 12 V battery has six cells in series, and a fully charged open-circuit reading is about 12.6-12.8 V, about 12.4 V at half charge.

Specific gravity of electrolyte in a fully charged lead-acid battery is about 1.260-1.280 at 25 degrees C; it falls as the battery discharges.

Alternator output is three-phase AC rectified by a diode bridge to DC; the voltage regulator holds about 13.8-14.5 V, and a reading below 13.2 V or above 15 V indicates a fault.

Starter motor draws high current (often 100-300 A) through a solenoid that also engages the pinion; voltage drop across a cable above about 0.5 V under load indicates high resistance.

A relay uses a small control current to switch a large load current; the coil is marked 85 and 86, contacts 30 (supply), 87 (load), and 87a (normally closed).

Fuses protect circuits by melting above rated current; a blown fuse must be replaced with the same rating, never a higher one or wire.

CAN bus is a twisted-pair differential serial network; a shorted CAN high to CAN low or to ground disables communication across modules on that bus.

Engine oil and filter change interval follows the manufacturer's schedule and oil specification (for example API or ACEA grade); the drain plug washer is renewed and torque is set to specification.

Air filter, fuel filter, and cabin filter are inspected at each service; a clogged air filter raises intake restriction and enriches the mixture on carburetted engines.

Brake inspection: pad friction material minimum is typically about 2 mm; disc runout and minimum thickness are checked against the stamped limit, and brake fluid is replaced on a time interval because it absorbs moisture.

Tyre pressures are set cold; tread depth legal minimum in India is 1.6 mm for cars, and uneven wear indicates alignment, inflation, or suspension faults.

Coolant level and strength are checked with a hydrometer or refractometer; a 50:50 mix gives freeze protection to about minus 37 degrees C and raises boiling point.

Battery terminals are cleaned and protected, and the charging voltage, electrolyte level (for serviceable batteries), and mounting are checked at every periodic service.

Periodic inspection items include lights, horn, wipers, seat belts, mirrors, exhaust leaks, suspension play, steering free play, and underbody leaks.

Pre-delivery inspection (PDI) covers fluid levels, tyre pressure, battery charge, electrical function, road test, and documentation before handover.

Service record entries should list date, odometer reading, work done, parts used, and next due interval so the maintenance history remains traceable.

Diagnostic sequence: verify the complaint, gather information, inspect visually, test, isolate the fault, repair, and verify the repair with a road test or re-test.

Engine will not start: check battery charge and cranking, then fuel delivery, then spark or injection pulse, then compression; a no-spark condition points to ignition coil, crank sensor, or wiring.

Engine overheating: check coolant level and leaks, thermostat operation, radiator fan, water pump belt, and head gasket (bubbles in coolant or white exhaust smoke).

Excessive oil consumption with blue smoke on acceleration indicates worn rings or valve guides; blue smoke on start-up after standing points to valve stem seals.

Brake pull to one side: check for a seized calliper, contaminated or glazed pads, unequal tyre pressure, or a collapsed brake hose.

Vibration at a specific speed often indicates wheel imbalance or a bent rim; vibration during braking indicates warped discs or drum distortion.

Battery drains overnight: measure parasitic current draw with a multimeter in series and isolate circuits by fuse removal until the draw drops to normal.

Scan tool use: read fault codes, then verify with live data and a wiring diagram; a code identifies the circuit or system, not necessarily the failed component.

Road test after repair confirms the fault is cleared and no new fault is introduced; the customer complaint is re-checked against the original description.

A job card records customer details, vehicle registration and odometer, reported complaint, work authorised, parts, labour, and signature of customer and technician.

An estimate must be approved by the customer before additional work is started; unapproved work is a common source of dispute.

Invoice items include part number, description, quantity, rate, labour hours, taxes, and total; GST rates and vehicle details must be shown as required.

Warranty claims require the failed part, job card reference, vehicle identification number, and a description of the failure mode as per the manufacturer's policy.

Vehicle handover: explain work done, parts replaced, next service due, and any deferred items; return replaced parts on request.

Confidentiality: customer contact details and vehicle data are not shared outside the workshop, and test drives are limited to the authorised purpose.

Honest diagnosis: never bill for parts not fitted or work not performed; recommend only work justified by inspection or test results.

Handling complaints: listen without interruption, acknowledge, investigate with evidence, offer a remedy within policy, and record the outcome.

Communication in service work includes active listening, clear explanation of technical faults in plain language, and confirming customer understanding.

Teamwork roles in a workshop: service advisor, technician, parts store keeper, quality inspector, and supervisor; each has defined responsibility for handover.

Time management: job scheduling by estimated labour time, prioritising safety-critical repairs, and tracking actual versus estimated hours.

Entrepreneurship basics: a business plan covers market demand, location, capital, equipment cost, staffing, pricing, and break-even volume.

Break-even quantity = fixed cost / (selling price per unit - variable cost per unit); it shows the minimum jobs per month needed to avoid loss.

Statutory requirements for a workshop business include GST registration where applicable, shop and establishment registration, pollution control compliance, and waste disposal authorisation.

Customer retention comes from transparent pricing, on-time delivery, and follow-up; a repeat customer costs less to serve than a new one.

Digital skills: using diagnostic scan tools, service software for job cards and inventory, and online parts catalogues are core employability skills.

Safety leadership: a technician who reports near-misses and follows lockout and PPE rules reduces workshop incidents and supports the 5S culture.