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HSC Automotive (VET) study materials
HSC Automotive (VET) study resources

HSC Automotive (VET) practice questions

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Question 1Automotive servicing and repair units of competency

Which document should a technician consult first to find the correct engine oil capacity and viscosity grade for a specific vehicle?

  1. A generic oil container label
  2. The vehicle registration certificate
  3. The vehicle manufacturer's workshop manual or specification data Correct answer.
  4. A tyre placard on the door jamb

Explanation

Manufacturer specification data gives the exact capacity and viscosity grade for each engine variant, including allowances for filter changes. Generic labels and registration papers do not carry vehicle-specific service data. Using the wrong grade or quantity can cause lubrication failure or overfilling.

Question 2Automotive servicing and repair units of competency

A vehicle is raised on a two-post hoist. Which practice best protects the technician before working underneath?

  1. Rely on the hydraulic pressure alone to hold the vehicle
  2. Place loose tools under the vehicle for easy access
  3. Lower the hoist onto its mechanical locks before going under Correct answer.
  4. Leave the engine running to keep the bay warm

Explanation

Mechanical locks are a positive restraint that holds the load if hydraulic pressure is lost. Hydraulics alone can bleed down and drop the vehicle. Tools underfoot create trip and crush hazards, and running engines add exhaust and moving-part risks in a confined area.

Question 3Automotive servicing and repair units of competency

What is the primary purpose of a torque wrench when tightening a cylinder head?

  1. To measure the angle of rotation of the bolt
  2. To apply a fastener load within the manufacturer's specified range Correct answer.
  3. To speed up the tightening of many bolts
  4. To check the hardness of the bolt material

Explanation

A torque wrench controls the rotational force applied so the fastener achieves the designed clamping load. Uneven or excessive torque can distort the head or stretch bolts. Angle gauges and hardness testers are separate tools used for different purposes.

Question 4Automotive servicing and repair units of competency

Which personal protective equipment is most important when using a compressed-air blow gun to dry components?

  1. Hearing protection only
  2. Steel-capped boots only
  3. Safety glasses and a face shield Correct answer.
  4. A welding helmet

Explanation

Compressed air can propel debris, fluid and metal particles toward the eyes and face at high velocity. Eye and face protection is the primary control. Boots and hearing protection serve other hazards, and a welding helmet is not designed for impact from particles.

Question 5Automotive servicing and repair units of competency

What does the abbreviation OBD stand for in vehicle diagnostics?

  1. Over-Boost Detection
  2. Oil Bypass Device
  3. Output Balance Display
  4. On-Board Diagnostics Correct answer.

Explanation

On-Board Diagnostics refers to the vehicle's self-monitoring system that stores fault codes and streams sensor data. Technicians access it through the diagnostic connector. The other expansions are invented terms with no diagnostic meaning.

Question 6Automotive servicing and repair units of competency

Which fluid level is checked with the transmission in neutral or park and the engine running on most automatic transmissions with a dipstick?

  1. Automatic transmission fluid Correct answer.
  2. Brake fluid
  3. Windscreen washer fluid
  4. Engine coolant

Explanation

Many automatic transmissions require the engine running and the selector in park or neutral so the pump fills the circuit and the dipstick reads a true level. Coolant, brake fluid and washer fluid are checked with the engine off. Checking ATF with the engine stopped can give a false high reading.

Question 7Automotive servicing and repair units of competency

A brake pedal feels spongy and travels close to the floor. Which condition most directly explains this symptom?

  1. Low engine oil level
  2. A blocked cabin air filter
  3. Worn front wheel bearings
  4. Air trapped in the hydraulic circuit Correct answer.

Explanation

Air is compressible, so bubbles in the hydraulic circuit absorb pedal force and produce a spongy feel and long travel. The repair is correct bleeding of the system. Bearings, cabin filters and engine oil do not affect brake pedal hydraulics.

Question 8Automotive servicing and repair units of competency

Why should a vehicle's battery be disconnected before replacing an alternator on most modern vehicles?

  1. To drain the capacitors in the alternator
  2. To reduce the weight of the alternator
  3. To prevent short circuits and damage to electronic modules Correct answer.
  4. To reset the radio station memory

Explanation

Disconnecting the battery removes live supply so tools cannot bridge the heavy charging cables to earth, which would cause arcs and module damage. It also protects sensitive electronics from voltage spikes during the repair. Radio memory loss is an unwanted side effect, not the reason.

Question 9Automotive servicing and repair units of competency

A scan tool shows a long-term fuel trim of +25 percent at idle. What does this most likely indicate?

  1. The fuel injectors are stuck open
  2. The engine is running excessively rich
  3. The oxygen sensor circuit is shorted to power
  4. The engine control unit is adding fuel to correct a lean condition Correct answer.

Explanation

Positive long-term fuel trim means the control unit is increasing injector pulse width because the exhaust indicates a lean mixture. A rich condition would drive trim negative. Stuck-open injectors and a shorted sensor circuit would also produce rich or fixed readings, not a consistent positive correction.

Question 10Automotive servicing and repair units of competency

During a compression test, one cylinder reads 40 percent lower than the others, but adding oil to the cylinder raises the reading. What does this suggest?

  1. Incorrect valve timing
  2. A burnt exhaust valve
  3. Worn piston rings or cylinder bore Correct answer.
  4. A leaking head gasket

Explanation

Oil temporarily seals the gap between rings and bore, so a rise after oiling points to ring or bore wear. Valve and head gasket faults are not sealed by oil because the leak path is in the head or sealing face. Valve timing affects all cylinders similarly.

Question 11Automotive servicing and repair units of competency

A customer reports a vibration that increases with road speed and is felt through the steering wheel. Which is the most appropriate first check?

  1. Check the engine coolant level
  2. Inspect front wheel balance and tyre condition Correct answer.
  3. Measure the battery voltage
  4. Test the alternator output

Explanation

Speed-related vibration through the steering wheel usually originates from front wheel imbalance, tyre runout or worn suspension components. Electrical and cooling checks do not address a rotational vibration. A structured road test and wheel inspection should come first.

Question 12Automotive servicing and repair units of competency

After replacing a brake caliper, which step is essential before the vehicle is returned to the customer?

  1. Bleed the hydraulic circuit and check pedal feel Correct answer.
  2. Replace the cabin air filter
  3. Reset the service interval only
  4. Top up the engine oil

Explanation

Opening the hydraulic circuit introduces air, so the system must be bled and the pedal checked for firmness and correct travel. A road test confirms operation. Engine oil, service reset and cabin filter are unrelated to brake hydraulic integrity.

Question 13Automotive servicing and repair units of competency

What is the correct way to store a refrigerant cylinder in an automotive workshop?

  1. Upright, secured, below the specified temperature and away from heat sources Correct answer.
  2. Loosely on a bench near the welding bay
  3. Lying on its side near a workshop heater
  4. In direct sunlight to keep it warm

Explanation

Refrigerant cylinders are pressure vessels that must be kept upright, restrained and below their rated temperature to avoid over-pressure and rupture. Heat sources and direct sunlight raise internal pressure. Sparks from welding add an ignition or decomposition risk with some refrigerants.

Question 14Automotive servicing and repair units of competency

A vehicle has a parasitic battery drain of 350 milliamps after all modules have gone to sleep. What is the most logical next step?

  1. Increase the alternator belt tension
  2. Measure current draw across fuses to isolate the circuit Correct answer.
  3. Replace the battery immediately
  4. Fit a larger fuse to the affected circuit

Explanation

Excessive sleep current means a circuit or module is staying awake. Measuring voltage drop or current across fuses isolates the offending circuit without disturbing harnesses. Replacing the battery masks the fault, and fitting a larger fuse increases risk rather than diagnosing it.

Question 15Automotive servicing and repair units of competency

Which measurement confirms that a starter motor is receiving full battery voltage at its main terminal during cranking?

  1. Resistance test with the circuit isolated
  2. Ohmmeter check across the starter solenoid coil
  3. Current clamp on the alternator output wire
  4. Voltage drop test across the heavy cable while cranking Correct answer.

Explanation

A voltage drop test under load shows the actual loss in the cable and connections while current flows. Resistance tests on an isolated circuit miss load-dependent faults. Alternator output and solenoid coil resistance do not confirm supply voltage at the starter terminal.

Question 16Automotive servicing and repair units of competency

A tyre is marked 205/55R16 91V. What does the 91 represent?

  1. The tread width in millimetres
  2. The maximum speed rating
  3. The load index of the tyre Correct answer.
  4. The aspect ratio as a percentage

Explanation

In this size designation the number after the construction letter is the load index, which corresponds to the maximum load the tyre can carry at its rated pressure. The letter V is the speed rating, 205 is the width and 55 is the aspect ratio. Confusing these values can lead to fitting an under-rated tyre.

Question 17Automotive servicing and repair units of competency

Which wheel alignment angle describes the tilt of the wheel's top edge inward or outward when viewed from the front?

  1. Thrust angle
  2. Camber Correct answer.
  3. Toe
  4. Caster

Explanation

Camber is the inward or outward lean of the wheel from vertical as seen from the front, which affects tyre wear and cornering grip. Caster is a steering-axis tilt seen from the side, toe is the difference in distance between wheel fronts and rears, and thrust angle relates to the rear axle direction.

Question 18Automotive servicing and repair units of competency

A diesel engine produces excessive black smoke under acceleration. Which cause is most consistent with this symptom?

  1. Excessive engine oil dilution
  2. A faulty glow plug relay
  3. Over-fuelling or restricted intake air Correct answer.
  4. Coolant entering the combustion chamber

Explanation

Black smoke is unburnt carbon from an over-rich air-fuel ratio, typically caused by excess fuel delivery or insufficient intake air. Coolant produces white smoke, and glow plug faults affect cold starting rather than steady-state smoke. Oil dilution is a consequence of other faults rather than a cause of black smoke.

Question 19Automotive servicing and repair units of competency

Why is a cooling system pressure-tested rather than only visually inspected?

  1. It confirms the radiator fan speed
  2. It measures the coolant concentration
  3. It checks the thermostat opening temperature
  4. It reveals leaks that appear only under pressure Correct answer.

Explanation

Many leaks, such as hairline cracks in a radiator tank or a failing head gasket seal, only open when the system is pressurised. Visual inspection cannot show these. Pressure testing does not measure coolant concentration, thermostat opening or fan speed, which require separate tests.

Question 20Automotive servicing and repair units of competency

A technician is asked to repair an SRS airbag circuit. Which precaution is mandatory before beginning work?

  1. Wear cotton gloves to insulate against current
  2. Remove the radio fuse only
  3. Disable the system and wait the manufacturer's specified time for capacitor discharge Correct answer.
  4. Simply turn off the ignition key

Explanation

Airbag modules contain capacitors that hold charge after the battery is disconnected, so the manufacturer's waiting time must be observed before disturbing components. Turning off the ignition alone leaves the system armed. Removing an unrelated fuse does not disarm the SRS, and gloves do not protect against deployment.

Question 21Automotive servicing and repair units of competency

An engine has a misfire code for cylinder 3. Swapping the ignition coil from cylinder 3 to cylinder 1 moves the misfire to cylinder 1. What is the most likely fault?

  1. The ignition coil itself is faulty Correct answer.
  2. There is a wiring fault to cylinder 3
  3. The spark plug in cylinder 3 is faulty
  4. The injector for cylinder 3 is blocked

Explanation

When a component swap transfers the fault to the new location, the swapped component is the cause. A faulty plug, injector or harness would keep the misfire on cylinder 3. This swap test is a standard diagnostic technique for isolating ignition faults.

Question 22Automotive servicing and repair units of competency

A vehicle with a CAN bus network has multiple unrelated modules offline. Which diagnostic approach is most appropriate?

  1. Ignore the fault as it will clear itself
  2. Replace every module one at a time
  3. Check network voltage levels and resistance at the diagnostic connector Correct answer.
  4. Replace the battery and retest

Explanation

Multiple modules dropping offline usually indicates a network-level fault such as a shorted bus line, incorrect termination resistance or a power/earth problem. Measuring bus voltages and resistance at the DLC quickly identifies the fault type. Random module replacement is costly and unlikely to resolve a shared network issue.

Question 23Automotive servicing and repair units of competency

A scan tool records a P0172 code (system too rich, bank 1). Which combination of live data would best support this diagnosis?

  1. Zero fuel trim with normal oxygen sensor switching
  2. Negative long-term fuel trim with high injector duty cycle Correct answer.
  3. Positive short-term trim with lean exhaust readings
  4. Positive long-term fuel trim with low injector duty cycle

Explanation

A rich condition causes the ECU to reduce fuel, producing negative trim, while the underlying fault may keep injector duty high as the ECU struggles to correct. Positive trim and lean readings indicate the opposite condition. Zero trim with normal switching indicates a healthy system.

Question 24Automotive servicing and repair units of competency

During a road test, a vehicle pulls to the left and the steering wheel is off-centre. Front tyre pressures are equal and the tyres are evenly worn. What is the most likely cause?

  1. Incorrect front wheel alignment, possibly toe or camber Correct answer.
  2. A faulty brake master cylinder
  3. A worn engine mount
  4. Low transmission fluid

Explanation

Equal tyre pressures and even wear rule out tyre-related pull, leaving alignment geometry as the likely cause of both the pull and the off-centre wheel. Toe or camber errors create a steering bias. Brake, transmission and engine mount faults produce different symptoms.

Question 25Automotive servicing and repair units of competency

An alternator produces 13.2 volts at idle with all accessories on, and the voltage drops further as load increases. Which conclusion is best supported?

  1. The voltage regulator is overcharging the battery
  2. Charging output is insufficient and the alternator or belt drive should be investigated Correct answer.
  3. The battery is fully charged and no action is needed
  4. The starter motor is drawing excessive current

Explanation

A healthy charging system typically maintains around 13.8 to 14.4 volts, and a reading near 13.2 volts that falls under load indicates inadequate output. Causes include a slipping belt, worn brushes or a failing regulator. Overcharging would show high voltage, and starter current is a separate circuit.

Question 26Automotive servicing and repair units of competency

Which document should a technician consult first to find the correct tightening torque for a cylinder head bolt on a specific vehicle?

  1. The torque specification stamped on the bolt head
  2. The parts catalogue listing for the head gasket
  3. A generic torque chart printed on the workshop wall
  4. The vehicle manufacturer's workshop manual for that model Correct answer.

Explanation

Torque figures vary between engines and fastener types, so the authoritative source is the manufacturer's service information for that exact model and engine. Generic charts and bolt markings do not account for thread type, lubricant, or torque-to-yield sequences.

Question 27Automotive servicing and repair units of competency

Which personal protective item is most important when using a solvent-based parts washer?

  1. A high-visibility vest
  2. Chemical-resistant gloves and eye protection Correct answer.
  3. Steel-capped boots only
  4. Hearing protection

Explanation

Solvents can damage skin and splash into the eyes, so chemical-resistant gloves and sealed eye protection are the primary controls. Boots and vests address other hazards and do not protect against solvent contact or splashing.

Question 28Automotive servicing and repair units of competency

What is the purpose of a torque wrench's click mechanism?

  1. To signal that the set torque has been reached Correct answer.
  2. To reverse the drive direction
  3. To measure the angle of rotation after tightening
  4. To lock the socket onto the fastener

Explanation

A click-type torque wrench releases or clicks once the preset torque is achieved, alerting the user to stop applying force. It does not grip the fastener, measure angle, or change drive direction.

Question 29Automotive servicing and repair units of competency

Which unit is used to express electrical resistance?

  1. Ampere
  2. Ohm Correct answer.
  3. Watt
  4. Volt

Explanation

Resistance is measured in ohms and represents opposition to current flow. Volts describe potential difference, amperes describe current, and watts describe power.

Question 30Automotive servicing and repair units of competency

When should an engine oil filter be replaced during routine servicing?

  1. Every second oil change regardless of oil type
  2. At every oil change Correct answer.
  3. Only when the filter housing shows external damage
  4. Only when the oil pressure warning light appears

Explanation

A used filter holds contaminated oil and its media becomes loaded, so replacing it with each oil change prevents trapped debris from re-entering the fresh oil. Waiting for a warning light means the engine has already run with reduced filtration.

Question 31Automotive servicing and repair units of competency

Which practice best prevents cross-threading when starting a spark plug by hand?

  1. Turn the plug anticlockwise until it seats, then tighten clockwise Correct answer.
  2. Coat the threads with thread-locking compound first
  3. Start the plug with a ratchet and extension
  4. Apply full torque immediately with a power tool

Explanation

Turning the plug backwards until it drops into the start of the thread aligns the threads before driving it in, greatly reducing the chance of cross-threading. Power tools and ratchets remove the feel needed to detect misalignment.

Question 32Automotive servicing and repair units of competency

Which component converts the rotational motion of the steering wheel into linear movement of the steering linkage in a conventional rack-and-pinion system?

  1. The tie-rod end
  2. The idler arm
  3. The steering damper
  4. The pinion gear acting on the toothed rack Correct answer.

Explanation

In rack-and-pinion steering the pinion, turned by the steering column, meshes with teeth on the rack and converts rotation into side-to-side movement. The idler arm belongs to recirculating-ball linkage systems, the damper controls oscillation, and the tie-rod end is a connecting joint.

Question 33Automotive servicing and repair units of competency

Which type of fire extinguisher is appropriate for a small fuel fire in a workshop?

  1. Water
  2. Dry chemical powder Correct answer.
  3. Carbon dioxide only
  4. Wet chemical

Explanation

Flammable liquid fires are class B, and dry chemical powder is rated for them and smothers the flame. Water spreads fuel, CO2 alone is best suited to electrical and small liquid fires but has limited rating for fuel pools, and wet chemical is designed for cooking oils.

Question 34Automotive servicing and repair units of competency

A customer complains that the engine cranks slowly and the battery terminals are visibly corroded. What is the most appropriate first step?

  1. Replace the battery
  2. Replace the starter motor
  3. Test the alternator output
  4. Clean the terminals and clamps and retest cranking Correct answer.

Explanation

Corrosion at the terminals raises resistance in the high-current cranking circuit and can cause slow cranking. Cleaning and retightening the connections is a quick, low-cost check that should be done before condemning expensive components.

Question 35Automotive servicing and repair units of competency

A vehicle's headlights dim noticeably when the engine is idling but brighten when engine speed is raised. Which condition best explains this?

  1. Charging system output is low at idle speed Correct answer.
  2. The headlight bulbs are the wrong wattage
  3. The battery has a high self-discharge rate
  4. The headlight relay is sticking open

Explanation

If brightness tracks engine speed, the alternator is not producing enough output at idle to carry the electrical load, so the system voltage sags. Raising engine speed increases alternator output and restores voltage.

Question 36Automotive servicing and repair units of competency

During a cooling system pressure test, the gauge holds pressure but drops slowly over ten minutes with no external leak visible. Which internal fault is most likely?

  1. A leaking head gasket or cracked casting Correct answer.
  2. A worn water pump bearing
  3. A faulty radiator cap seal
  4. A stuck-open thermostat

Explanation

A slow pressure loss with no external trace suggests coolant is escaping into the combustion chamber or oil galleries through a failed gasket or cracked casting. A thermostat, cap, or pump bearing would show different symptoms.

Question 37Automotive servicing and repair units of competency

A manual transaxle jumps out of third gear under acceleration. Which cause is most consistent with this symptom?

  1. Low clutch fluid level
  2. A worn CV joint boot
  3. Incorrect tyre pressure
  4. Worn detent springs or a damaged third-gear synchro hub Correct answer.

Explanation

Gear disengagement under load usually points to worn detents, shift forks, or synchro hub components that no longer hold the gear engaged. Clutch hydraulics, CV boots, and tyre pressures affect other functions.

Question 38Automotive servicing and repair units of competency

A technician is preparing to weld a panel on a vehicle fitted with numerous electronic control modules. Which precaution protects the modules?

  1. Remove the ECU fuse only
  2. Connect a charger to the battery during welding
  3. Leave the engine running to maintain voltage
  4. Disconnect the battery and unplug sensitive modules near the work area Correct answer.

Explanation

Welding sends high currents and voltage spikes through the body, so the battery should be disconnected and modules near the weld area unplugged. Running the engine or charging during welding increases risk to electronics.

Question 39Automotive servicing and repair units of competency

A vehicle's engine oil warning light illuminates at idle when hot but goes out when engine speed increases. Which check should be performed first?

  1. Verify oil pressure with a mechanical gauge Correct answer.
  2. Change the oil to a thicker grade
  3. Replace the oil pressure switch
  4. Replace the oil pump

Explanation

The symptom could come from a faulty switch or from genuinely low pressure, so confirming actual pressure with a mechanical gauge separates the two. Replacing parts or changing oil grade before measuring risks masking a serious internal fault.

Question 40Automotive servicing and repair units of competency

Which inspection method is best for detecting a worn ball joint on a front suspension?

  1. Check the shock absorber for oil residue
  2. Load the joint with a pry bar and check for vertical movement Correct answer.
  3. Measure tyre tread depth
  4. Spin the wheel and listen for bearing noise

Explanation

Applying load with a pry bar while observing the joint reveals free play that indicates wear. Bearing noise, tread depth, and shock absorber leakage relate to different components.

Question 41Automotive servicing and repair units of competency

A diesel engine is hard to start when cold but starts readily when warm. Which component should be tested first?

  1. The EGR valve position sensor
  2. The glow plugs and their control circuit Correct answer.
  3. The turbocharger wastegate
  4. The fuel tank breather

Explanation

Cold starting in a diesel relies on glow plugs heating the combustion chamber, so a failure there produces exactly this warm-starts-fine pattern. Turbo, EGR, and breather faults do not typically depend on cold temperature.

Question 42Automotive servicing and repair units of competency

What is the correct procedure for lifting a vehicle on a two-post hoist?

  1. Place the arms under the exhaust and fuel tank
  2. Lift one side fully before the other
  3. Position the arms at the manufacturer's lifting points and raise slowly while checking stability Correct answer.
  4. Lift by the sills anywhere along the body

Explanation

Manufacturer lifting points are reinforced to carry the vehicle's weight, and raising slowly while checking allows any instability to be corrected. Lifting at arbitrary body areas or under soft components can cause damage or collapse.

Question 43Automotive servicing and repair units of competency

A scan tool shows a coolant temperature sensor reading of minus 40 degrees Celsius on a warm engine. Which diagnosis is most likely?

  1. Air trapped in the cooling system
  2. A faulty thermostat stuck open
  3. An open circuit in the sensor signal circuit Correct answer.
  4. A short to ground in the sensor signal circuit

Explanation

A very low, fixed temperature reading typically indicates the signal circuit is open, so the control module sees a default extreme. A short to ground usually drives the reading high, and thermostat or air-lock faults would not produce a fixed implausible figure.

Question 44Automotive servicing and repair units of competency

Which statement correctly describes the function of a relay in an automotive circuit?

  1. It converts alternating current to direct current
  2. It reduces voltage by a fixed amount
  3. It stores electrical energy for later use
  4. It uses a small control current to switch a larger load current Correct answer.

Explanation

A relay is an electromagnetically operated switch that lets a low-current control circuit energise a high-current load circuit. Rectification, energy storage, and voltage reduction are performed by other devices.

Question 45Automotive servicing and repair units of competency

An apprentice must remove a fuel tank from a vehicle. Which sequence is safest?

  1. Drain the tank onto the floor and then unbolt it
  2. Disconnect the fuel lines while the engine is running
  3. Loosen all tank straps at once and let the tank drop
  4. Relieve fuel pressure, disconnect the battery, then support and lower the tank Correct answer.

Explanation

Releasing residual pressure and isolating the battery removes the risk of spray and ignition before any line is opened, and supporting the tank prevents it falling. Draining to the floor, working with the engine running, or dropping the tank all create fire or crush hazards.

Question 46Automotive servicing and repair units of competency

A vehicle's rear brake shoes wear unevenly, with one shoe much thinner than the other. Which cause is most likely?

  1. Low brake fluid level
  2. Warped front brake rotors
  3. A faulty brake light switch
  4. A seized or incorrectly adjusted self-adjuster Correct answer.

Explanation

Drum brakes rely on the self-adjuster to keep both shoes at equal clearance, so a seized or misadjusted mechanism causes one shoe to do more work. Fluid level, front rotors, and the brake light switch do not cause uneven rear shoe wear.

Question 47Automotive servicing and repair units of competency

A battery is being charged with a smart charger. Which observation indicates the battery may have an internal short?

  1. The terminal voltage rises slowly during charging
  2. The charger fan runs continuously
  3. The charger indicates a full charge after several hours
  4. The battery warms abnormally while accepting very little charge Correct answer.

Explanation

An internal short converts charging current into heat instead of stored energy, so the case warms while charge acceptance stays poor. Normal charging produces a gradual voltage rise and a full-charge indication without excessive heat.

Question 48Automotive servicing and repair units of competency

A vehicle with an electronically controlled automatic transmission flares between second and third gear under light throttle. Which data should be reviewed first to isolate the cause?

  1. Line pressure and shift solenoid command versus actual gear ratio Correct answer.
  2. Wheel speed sensor readings during braking
  3. Engine coolant temperature and intake air temperature
  4. Fuel trim values at idle

Explanation

A flare means engine speed rises without a corresponding ratio change, so comparing commanded solenoid state and line pressure with the calculated ratio shows whether the fault is hydraulic or electronic. Temperature, wheel speed, and fuel trim data do not directly describe the shift event.

Question 49Automotive servicing and repair units of competency

A technician measures 0.9 volts drop across the earth return of a starter circuit during cranking. What does this indicate?

  1. An overcharged battery
  2. Normal operation because some drop is always present
  3. Excessive resistance in the earth path that should be corrected Correct answer.
  4. A faulty starter solenoid winding

Explanation

Voltage drop testing shows how much potential is lost across a connection; a reading approaching one volt on an earth return is excessive and will reduce cranking performance. Normal earth paths should show only a small fraction of that drop.

Question 50Automotive servicing and repair units of competency

An engine management system uses a wideband oxygen sensor. Which condition would cause the sensor's pump current to indicate a lean mixture while the engine is actually running rich?

  1. A restricted fuel filter
  2. A faulty ignition coil on one cylinder
  3. A clogged air filter element
  4. An air leak into the exhaust upstream of the sensor Correct answer.

Explanation

A wideband sensor measures oxygen in the exhaust gas reaching it, so air entering upstream of the sensor dilutes the sample and makes the reading appear lean even if combustion is rich. A restricted fuel filter, dirty air filter, or single-cylinder misfire would not add oxygen at the sensor.