Maintenance Tools and Service Basics Lesson Test

Answer: C

Correct answer: A correctly sized box-end wrench. A box-end wrench has a closed ring that surrounds the bolt head and grips it on all sides, so it spreads force evenly and is less likely to slip or round off the corners than an open-end wrench. The exact size matters, because a loose fit concentrates force on the corners. Screwdrivers fit slots or recesses, feeler gauges measure gaps and grease guns lubricate fittings, so none of them can turn a hex head.

• A: Incorrect: A screwdriver of any width turns a matching screw slot, not a hex bolt head.
• B: Incorrect: Its coupler dispenses lubricant into a fitting and cannot grip a bolt.
• C (correct): Correct: The closed wrench ring engages the proper flats of the fastener when access permits.
• D: Incorrect: Its thin blades measure gaps rather than turn fasteners, whatever their thickness.

Answer: A

Correct answer: A breaker bar. A breaker bar has a long, solid handle and a pivoting head with no pawl to break, so its length produces a large turning force. The usual practice is to break the nut loose with the bar, then spin it off with a ratchet.

• A (correct): A breaker bar is a long, solid handle with no ratchet mechanism, so its length delivers high torque for loosening tight nuts.
• B: A torque wrench is a measuring tool for final tightening and should never be used to loosen stuck fasteners.
• C: Pliers bite into the corners of a nut and round it off; they are not a substitute for a wrench or socket.
• D: A ratchet is meant for quickly running fasteners in and out; extreme force can damage its internal pawl.

Answer: D

Correct answer: A feeler gauge. A feeler gauge is a set of thin steel blades, each stamped with its exact thickness. To check a gap, you slide in blades until one passes with light drag; that blade's marked thickness is the clearance. A scan tool can be tempting because it is a diagnostic tool, but it reads electronic data from vehicle modules and cannot physically measure the space between two parts. Spark-plug gaps and valve lash are classic feeler-gauge jobs.

• A: Incorrect: Scan data does not directly measure a mechanical clearance.
• B: Incorrect: A stand supports a raised load rather than measuring a gap.
• C: Incorrect: A pan captures fluid; it has no measuring blade.
• D (correct): Correct: Its blades provide known thicknesses for checking a designated clearance.

Answer: A

Correct answer: It lifts a vehicle but must not be the sole support underneath a person. A floor jack is designed to raise a load, not hold it for long. Its weight rests on hydraulic fluid held in place by seals and valves, and a leak, a bumped handle or a shifting vehicle can let it drop without warning. The safe sequence is to lift with the jack, then lower the vehicle onto rated jack stands at the specified support points before anyone gets underneath. Setting the parking brake helps, but it does nothing to keep the jack itself from failing.

• A (correct): Correct: Approved rated stands or support systems are essential when an elevated vehicle is worked under.
• B: Incorrect: Foundation, lifting location and stability remain critical even with the parking brake set.
• C: Incorrect: A lifting jack does not measure turning torque.
• D: Incorrect: Hydraulic pressure alone is not safe continuous support, because seals and valves can fail.

Answer: D

Correct answer: The socket engages the fastener; the ratchet provides indexed turning action. Think of the pair as an interchangeable system: sockets come in many sizes and fit over the fastener, while one ratchet handle drives them all through a square drive. Inside the ratchet, a pawl and gear let the handle turn the socket in one direction and click back freely in the other, so you can keep turning without lifting the tool off. Neither part sets a final torque; that job belongs to a torque wrench.

• A: Incorrect: Neither tool measures temperature or pressure.
• B: Incorrect: A socket alone provides no calibrated torque indication.
• C: Incorrect: Sockets are fastener-engagement tools, not wire strippers.
• D (correct): Correct: The two components have different, complementary functions.

Answer: B

Correct answer: Exhaust carbon monoxide can build up and poison people. Engine exhaust contains carbon monoxide, an odorless, colorless gas that prevents the blood from carrying oxygen. In a closed garage it builds up quickly, so engines must run only with an outdoor-vented exhaust hose and good ventilation.

• A: The most dangerous exhaust gas has no odor at all, so smell is not the concern.
• B (correct): Carbon monoxide is colorless and odorless and keeps blood from carrying oxygen, so it can kill in an enclosed space.
• C: Hydrogen from batteries is a separate hazard and is not produced by running the engine in a closed space.
• D: Overheating is not the main hazard; the danger is to the people breathing the exhaust.

Answer: B

Correct answer: Remove the tool from service until properly repaired or replaced. Cord insulation is what keeps the user from touching live conductors. Once it is cut or cracked, the exposed wire can shock the user or short and start a fire. A rag or other makeshift wrap does not have a voltage rating, so it cannot restore that protection. Raising the breaker rating is especially dangerous because the breaker protects the wiring and a larger one lets more current flow before it trips. Tag the tool out of service and have the cord properly replaced.

• A: Incorrect: Cloth cannot restore appropriate electrical insulation.
• B (correct): Correct: Damaged cords create shock and fire hazards; inspection and safe condition are essential.
• C: Incorrect: A larger breaker can make overcurrent protection less effective.
• D: Incorrect: Tool speed is unrelated to safe insulation.

Answer: C

Correct answer: An OBD-compatible scan tool. Since 1996, cars and light trucks sold in the U.S. have used OBD-II, a standard onboard diagnostic system with a connector usually found under the dashboard. A scan tool plugs into that port and asks the vehicle's computer for stored trouble codes and live sensor data. A digital caliper can look tempting because it has a screen, but it only measures physical size. A code tells you which monitored condition failed, which guides further testing.

• A: Incorrect: A hammer transfers impacts and cannot read module data.
• B: Incorrect: A lug wrench turns wheel fasteners.
• C (correct): Correct: A scan tool communicates with vehicle diagnostic systems where supported.
• D: Incorrect: A caliper measures physical dimensions and cannot read module data.

Answer: B

Correct answer: A correctly sized six-point socket. Rounding happens when force is concentrated on the corners of a hex head instead of the flat sides. A six-point socket has exactly six flats that match the head, so it pushes on the sides of the flats and leaves the corners alone. A twelve-point socket has more engagement positions, but its contact is closer to the corners, so it is more likely to slip on a tight or worn fastener. Locking pliers bite into the corners and often cause the very damage you are trying to avoid.

• A: Incorrect: Added paper prevents correct metal engagement.
• B (correct): Correct: Proper socket contact on flats commonly reduces slip versus an ill-fitting tool.
• C: Incorrect: Serrated jaws can damage hex corners.
• D: Incorrect: A screwdriver does not fit a hex head.

Answer: D

Correct answer: They help protect eyes from hazards such as flying particles. Safety glasses are personal protective equipment (PPE), the last line of defense after hazards have been removed or guarded. Impact-rated lenses and side shields stop chips, dust and splashes from grinding, drilling or cutting. The common misconception is that wearing PPE makes other precautions optional. Glasses protect only the eyes, so machine guards, insulated tools and safe procedures are still required for hands, body and electrical hazards.

• A: Incorrect: High voltage requires trained isolation and rated equipment.
• B: Incorrect: PPE cannot restore damaged tools.
• C: Incorrect: Eye protection cannot prevent contact with rotating or cutting parts.
• D (correct): Correct: Task-appropriate PPE mitigates exposure but does not replace machine guards and safe work methods.

Answer: B

Correct answer: 17.5 N·m. For a force applied at a right angle, torque is distance times force.

• A: This value has a misplaced decimal point; 0.35 times 50 is 17.5, not 1.75.
• B (correct): Torque equals distance times force: 0.35 m times 50 N gives 17.5 N·m.
• C: This comes from dividing the force by the distance instead of multiplying them.
• D: This adds the distance to the force; torque is their product, not their sum.

Answer: A

Correct answer: Use a suitable calibrated torque wrench and manufacturer instructions. Bolts work like stiff springs: tightening stretches them slightly, and that stretch creates the clamping force that holds parts together. Too little torque lets the joint loosen; too much can stretch the bolt beyond its limit or strip the threads. A calibrated torque wrench lets you reach the manufacturer's value, often in a specified tightening sequence such as a crisscross pattern for wheels. An impact wrench or long breaker bar delivers force but gives no reading, so the final torque is guesswork.

• A (correct): Correct: The correct tool, specified value and sequence matter for the joint.
• B: Incorrect: Impact stall torque is not controlled final torque.
• C: Incorrect: A breaker bar supplies leverage but does not read torque.
• D: Incorrect: Appearance is not a quantitative joint-clamp criterion.

Answer: D

Correct answer: It can offer additional indexing positions for engagement. A six-point socket can engage a hex head only every 60 degrees, but a twelve-point socket can drop on every 30 degrees. In a cramped space where the handle can swing only a short arc, those extra positions make it easier to fit the socket and keep turning. The tradeoff is grip: twelve-point contact is closer to the corners, so it is more likely to round off a tight fastener. Socket shape never changes leverage or bolt size.

• A: Incorrect: A socket is not an electrical instrument.
• B: Incorrect: Socket points do not multiply leverage.
• C: Incorrect: The fastener dimensions do not change.
• D (correct): Correct: Twelve-point geometry can allow more angular approach choices when correctly matched.

Answer: D

Correct answer: A suitably ranged micrometer. A micrometer uses a finely threaded spindle; each turn of the thimble advances it a tiny known distance, so it typically reads to 0.001 inch or 0.01 millimeter. Each micrometer covers a limited range, such as 0 to 1 inch, which is why you must pick one sized for the part. A scan tool can seem plausible because it gives precise numbers, but those values come from electrical sensors, not from measuring a part's thickness. Brake rotors are commonly checked against a minimum-thickness specification this way.

• A: Incorrect: Its blade is not a calibrated thickness instrument.
• B: Incorrect: Vehicle code and live data do not directly give a physical part thickness.
• C: Incorrect: Its toothed jaws grip round piping rather than measure to tolerance.
• D (correct): Correct: A properly used micrometer measures small outside dimensions precisely.

Answer: C

Correct answer: 2 A. Resistors in series add:

Then apply Ohm's law.

• A: This adds 12/2 and 12/4 as if each resistor had the full 12 V across it, which treats a series circuit like a parallel one.
• B: This divides resistance by voltage (6/12), which inverts Ohm's law.
• C (correct): Series resistances add to 6 ohms, and 12 V divided by 6 ohms is 2 A.
• D: This multiplies voltage by resistance; Ohm's law gives current as voltage divided by resistance.

Answer: C

Correct answer: They may not be rated to withstand repeated impact loads. An impact wrench drives the socket with rapid hammer blows rather than a smooth, steady pull. Ordinary chrome sockets are hard but relatively brittle, so repeated shock loads can crack or shatter them and throw fragments. Impact sockets are made of tougher steel, usually have thicker walls, and carry a black oxide finish that makes them easy to spot. Size is not the difference; a 14 mm chrome socket and a 14 mm impact socket fit the same fastener.

• A: Incorrect: Both types can have compatible square drive interfaces.
• B: Incorrect: Sockets are not electrical energy stores.
• C (correct): Correct: Impact-rated sockets and accessories are designed for the relevant pulse-loading demands.
• D: Incorrect: Opening size can be the same on both types.

Answer: D

Correct answer: A circuit condition was detected, but wiring and other causes remain possible. The engine computer sets a code when a monitored signal falls outside its expected range, but it cannot tell where along the circuit the problem lies. A failed sensor, a corroded connector, a broken wire or a fault in the computer itself can all produce the same code. The tempting mistake is to buy the named part first. Good diagnosis means checking wiring, connections and the sensor's signal so you replace only what is actually faulty.

• A: Incorrect: A sensor-circuit code does not prove this coolant state.
• B: Incorrect: Oil filtering has nothing to do with this sensor code or how its circuit is tested.
• C: Incorrect: Code text alone cannot exclude connector or wiring issues, so replacement is premature.
• D (correct): Correct: A DTC identifies monitored conditions, not automatically the failed individual component.

Answer: C

Correct answer: 0.512 in. One inch is exactly 25.4 mm, so divide millimeters by 25.4 to get inches.

That is close to 1/2 in but not the same, so a 1/2-inch wrench would be a slightly loose fit.

• A: This simply moves the decimal point, as if 1 inch were 100 mm instead of 25.4 mm.
• B: This multiplies by 25.4, which converts inches to millimeters rather than millimeters to inches.
• C (correct): Dividing 13 mm by 25.4 mm per inch gives about 0.512 in.
• D: This divides 25.4 by 13, flipping the division the wrong way.

Answer: B

Correct answer: Voltage is observed across points; current is usually measured in series. Voltage is the difference in electrical pressure between two points, so a voltmeter is connected in parallel across the part being tested, and its very high internal resistance draws almost no current. Current is the flow through a path, so the circuit is opened and the ammeter is inserted in series, letting all the current pass through it. An ammeter has very low resistance; connected straight across a battery, it acts as a short circuit and can blow the meter's fuse or damage it.

• A: Incorrect: Current mode directly across a source can short it.
• B (correct): Correct: A voltmeter measures potential difference whereas conventional ammeter placement follows current flow.
• C: Incorrect: Mechanical thickness blades do not measure current.
• D: Incorrect: A voltage reading does not require an opened series path in the model.

Answer: C

Correct answer: Use oil and filter specifications approved for that exact engine. Engines are designed around specific oil properties. The viscosity grade, such as 5W-30, describes how the oil flows when cold and when hot, and approval standards cover additives that protect parts such as turbochargers or emissions equipment. Filters also differ inside, in thread size, gasket shape, bypass valve setting and anti-drainback valve, even when two look alike. A filter that looks right may still leak or starve the engine of oil. Always check the owner's manual or service data for the exact requirement.

• A: Incorrect: That is not a valid general filling specification.
• B: Incorrect: Viscosity and performance certifications affect suitability at every temperature.
• C (correct): Correct: Different engines and service conditions can require distinct products and procedures.
• D: Incorrect: Appearance cannot validate thread, seal or bypass characteristics.

Answer: D

Correct answer: Some joints are sealed or require a particular lubricant and application method. Many modern ball joints and tie-rod ends are sealed at the factory with lifetime lubricant and have no grease fitting. Forcing grease into such a joint can rupture its boot and let in dirt and water. Serviceable joints have a zerk fitting, and the manufacturer specifies the grease type and service interval. Another misconception is that greasing fixes looseness; lubrication slows wear but cannot restore a worn joint, which must be inspected and replaced if it is beyond limits.

• A: Incorrect: Lubrication does not restore damaged hardware.
• B: Incorrect: They are generally designed for grease.
• C: Incorrect: A grease gun does not measure joint wear limits.
• D (correct): Correct: A grease fitting or manufacturer instruction determines serviceability and material.

Answer: B

Correct answer: The size of the bolt head or nut it fits. A socket has two separate sizes. The drive size (3/8 in) is the square hole for the ratchet or extension, while the opening size (17 mm) is the hex head it fits; the two numbers are unrelated.

• A: That is the drive size, which here is the 3/8 in marking, not the 17 mm marking.
• B (correct): The opening size names the fastener the socket fits, here a 17 mm hex head.
• C: Drive size is a separate square-hole measurement; the 17 mm figure is unrelated to the handle.
• D: Socket markings for size describe the opening, not the overall length of the socket.

Answer: D

Correct answer: Unexpected motion or stored energy may injure the worker. Machines can move even when they seem to be off. Someone may switch the power back on, or stored energy in springs, hydraulic pressure, capacitors or raised parts can be released suddenly. Lockout/tagout procedures isolate every energy source, attach a lock and tag so it cannot be restarted, and then verify that the equipment is at zero energy before work begins. Controlling energy is separate from PPE: safety glasses are still needed even after the power is locked out.

• A: Incorrect: PPE requirements are separate from energy-control procedures.
• B: Incorrect: Isolation is not a calibration operation.
• C: Incorrect: Energy isolation has no such relationship.
• D (correct): Correct: Hazardous-energy protection addresses startup and residual energy hazards.

Answer: D

Correct answer: It can create particle and injection hazards, and regulated safeguards may be required. Compressed air can drive dust, metal chips and fluids into the eyes at high speed, and a nozzle held against the skin can force air into the tissue or bloodstream, causing serious injury. For this reason, OSHA limits air used for cleaning to under 30 psi when the nozzle is dead-ended and requires chip guarding and personal protective equipment. A common misconception is that blowing off clothing is harmless, but directing air at the body is a known source of injury.

• A: Incorrect: Air blows debris outward, so flying particles remain a risk.
• B: Incorrect: High-pressure air can enter and injure tissues.
• C: Incorrect: Directing compressed air at the body creates serious hazards, especially at full pressure.
• D (correct): Correct: OSHA general-industry cleaning restrictions involve reduced air pressure, chip guarding and PPE where allowed.

Answer: B

Correct answer: Opening a hot pressurized cooling system can cause serious scalding. A cooling system is sealed and pressurized so the coolant can get hotter than its normal boiling point without boiling. If the cap is opened while it is hot, the pressure drops suddenly and the coolant can flash into steam and spray out, causing severe burns. Turning off the ignition stops the engine, but the heat and pressure remain for some time. Let the engine cool, then open the cap slowly with a cloth so any remaining pressure can escape.

• A: Incorrect: Thermal expansion and system design affect pressure.
• B (correct): Correct: Follow the vehicle procedure and ensure conditions are safe before any cap service.
• C: Incorrect: A rag cannot guarantee pressure release safety.
• D: Incorrect: Residual heat and pressure may remain after the engine stops.

Answer: A

Correct answer: It provides an appropriate grip for the designed filter type. Oil filters come in two main forms: spin-on canisters and cartridge filters held in a housing with a cap. A filter wrench is designed to grip one of these shapes, whether with a band, a cap-style cup that fits the end, or adjustable jaws, so it can be loosened without crushing it. Choose the style and size that fit the filter. The wrench only grips and turns; oil level is checked with the dipstick, and electrical problems require a meter.

• A (correct): Correct: Filter wrench form must match the filter and service procedure.
• B: Incorrect: The tool does not adjust steering geometry.
• C: Incorrect: Gripping a filter is mechanical, not diagnostic electronic measurement.
• D: Incorrect: Fluid quantity is established through service instructions and measurement.

Answer: A

Correct answer: 0.27 mm. Wear is the original size minus the measured size.

Compare that result, or the measured size, with the service limit.

• A (correct): Wear is 30.00 mm minus 29.73 mm, which equals 0.27 mm.
• B: This reads only the decimal part of the measurement instead of subtracting it from 30.00 mm.
• C: This adds the two diameters; wear is the difference between original and measured size.
• D: The decimal point is misplaced; the difference is 0.27 mm, ten times smaller.

Answer: C

Correct answer: It helps resist unintended rolling under an appropriate setup. Wheel chocks are wedges placed against the tires that stay on the ground, usually on the end opposite the one being lifted. When one end of a vehicle goes up, the remaining wheels can roll, and the vehicle can slide off the jack or stands. Chocks hold the vehicle in place along with the parking brake and the transmission in Park or in gear. They do not hold up any weight, so rated stands are still needed under the raised end.

• A: Incorrect: A wedge is not a calibration device.
• B: Incorrect: Chocks do not support a raised axle; rated stands do.
• C (correct): Correct: Chocks are one control in a larger support and immobilization strategy.
• D: Incorrect: Immobilization uses multiple appropriate measures together.

Answer: B

Correct answer: Stop using it until the guard or tool is properly repaired. Guards on grinders, saws and similar tools keep hands away from blades and contain fragments if a wheel or bit breaks. A loose guard can shift into the moving part or fail to block debris, so the tool should be tagged out until it is repaired. Removing a guard may seem to improve visibility, but it exposes you to the exact hazards the guard is designed to stop. Eyewear protects only the eyes and is not a substitute for a guard.

• A: Incorrect: This increases exposure to moving or cutting hazards.
• B (correct): Correct: Required guards prevent exposure to moving components and must not be bypassed.
• C: Incorrect: A hazardous condition becomes worse at higher operating speed.
• D: Incorrect: Sunglasses do not replace required guards.

Answer: C

Correct answer: The underlying monitored condition may still exist. Clearing codes only erases the computer's memory; it does not fix whatever caused the fault. The computer keeps running its self-tests, and if the same condition is detected again, the code and warning light come back, sometimes immediately and sometimes after a few drive cycles. A light that returns right away indicates an active fault. Record the codes and freeze-frame data before clearing them, since clearing can erase details that help with diagnosis.

• A: Incorrect: Paperwork does not repair faults.
• B: Incorrect: A repeated indicator can have many root causes.
• C (correct): Correct: Clearing diagnostic information cannot guarantee repair of the root cause.
• D: Incorrect: No such universal logic follows.

Answer: A

Correct answer: 54 N·m. An in-line crowfoot makes the lever longer, so the fitting gets more torque than the wrench shows.

Setting 54 N·m delivers 60 N·m at the fitting.

• A (correct): Setting = 60 times 0.45 divided by (0.45 + 0.05), which equals 54 N·m.
• B: This multiplies by the extra reach over the wrench length instead of the wrench length over the total length.
• C: This uses the ratio upside down; an in-line crowfoot lengthens the lever, so the setting must be lower than the spec, not higher.
• D: No correction is needed only when the crowfoot is turned 90 degrees to the handle; in line it adds leverage and overtightens.

Answer: C

Correct answer: 20 N·m. When the force is not perpendicular, use

That is half of the 40 N·m a right-angle pull would give.

• A: This is the torque for a right-angle pull; at 30 degrees only part of the force turns the bolt.
• B: This uses the cosine of 30 degrees; the turning part of the force uses the sine of the angle to the handle.
• C (correct): Torque = 0.50 m times 80 N times sin 30 degrees (0.5), which is 20 N·m.
• D: This divides the force by the distance instead of multiplying and ignores the angle.

Answer: D

Correct answer: 0.9 V. A voltage drop test compares readings taken while current flows. The cables start with what the loaded battery supplies and end at the starter.

The resting 12.6 V figure is not used, because the battery's own output falls under load.

• A: This compares the starter with the resting reading; part of that loss happens inside the battery under load, not in the cables.
• B: This adds the two loaded readings; a voltage drop is the difference between them.
• C: This is the drop at the battery itself from rest to cranking, not the loss in the cables and connections.
• D (correct): Under load the battery delivers 11.8 V and the starter receives 10.9 V, so the wiring between them loses 0.9 V.

Answer: A

Correct answer: Turn off power and isolate the element before measuring. An ohmmeter measures resistance by sending its own small current through the part. Any outside voltage corrupts that reading and can damage the meter, so power must be off and the part disconnected or its fuse removed before measuring.

• A (correct): An ohmmeter needs a de-energized, isolated part, so switch off the circuit and disconnect the element or pull its fuse first.
• B: The amps jack is for series current measurement; placing it across a powered part can blow the meter's fuse.
• C: A glowing test light only shows voltage is present; it does not measure resistance or prove the element is faulty.
• D: Circuit voltage interferes with the ohmmeter's own small test current, giving a false reading and possibly damaging the meter.

Answer: A

Correct answer: 0.4 mm. The difference is

with the acceptance decision set by the service document.

• A (correct): Correct: The difference is 23.0−22.6=0.4 mm, with the acceptance decision set by the service document.
• B: Incorrect: The subtraction was miscomputed.
• C: Incorrect: Adding the measurements does not find wear-limit deficit.
• D: Incorrect: This uses the wrong decimal place and is ten times too small for the stated difference.

Answer: C

Correct answer: 0.16 mm. Maximum minus minimum is

• A: Incorrect: Total indicated runout is presented as a positive magnitude.
• B: Incorrect: Subtracting magnitudes incorrectly loses the negative sign.
• C (correct): Correct: Maximum minus minimum is 0.12−(−0.04)=0.16 mm.
• D: Incorrect: This uses only the maximum rather than peak-to-peak motion.

Answer: A

Raising the rear means the front wheels stay on the ground, so those are chocked, with the parking brake set and the transmission in Park. After lifting at the maker's point, the car is lowered onto a matched pair of rated jack stands and checked for steadiness before anyone goes under; the jack only lifts.

• A (correct): This chocks the wheels that stay on the ground, uses the listed lift point, and puts the weight on rated stands before anyone goes under.
• B: A jack is a lifting tool only, whatever its rating; its hydraulic seals can leak down and it can roll or tip.
• C: The rear wheels leave the ground, so chocking them does nothing, and a jack alone must never support a car with a person underneath.
• D: Blocks and bricks can crumble without warning; only rated jack stands are acceptable supports, and the front wheels were not chocked.

Answer: B

Correct answer: Wait until the tires are cold, then check and adjust to 35 psi. Heat from driving raises tire air pressure, so a hot reading is temporarily above the cold specification. Letting air out now would leave the tires low once they cool, so recheck cold and set them to the door-jamb value.

• A: The sidewall number is a limit for the tire, not the vehicle's recommended pressure, which is on the door-jamb label.
• B (correct): Driving heats the air and raises pressure, so the label value applies to a cold reading.
• C: The 39 psi reading is caused by heat; the correct setting is still 35 psi measured cold.
• D: The hot reading is temporarily high; bleeding it down now leaves the tires underinflated once they cool.

Answer: B

Correct answer: Choose the tool loading and input protection specified for the circuit. Every tester draws some current from the circuit it is connected to, which is called loading. An incandescent test light can draw enough current to pull a weak signal down or overload a low-current input, giving a false reading or damaging the electronics. A high-impedance digital multimeter, often rated at 10 megohms, draws so little current that it reads the signal without disturbing it. A test light that worked on the battery is no guarantee it is safe on sensitive circuits.

• A: Incorrect: A jack is not an appropriate circuit-testing tool.
• B (correct): Correct: A test light may load or damage sensitive circuits; rated high-impedance methods may be needed.
• C: Incorrect: Some test lights draw enough current to damage sensitive circuits.
• D: Incorrect: Deliberate shorting is unsafe and not an approved diagnostic.

Answer: A

Correct answer: The reading cannot be trusted; remeasure with a calibrated instrument. Resolution is the smallest step shown, accuracy is closeness to the true value, and tolerance is the allowed range. A micrometer that is 0.08 mm off could hide a part that is actually outside the 0.10 mm-wide range, so the measurement must be repeated with a calibrated instrument before passing or failing the part.

• A (correct): An out-of-calibration tool can show precise-looking numbers that are wrong, so judge the part only with a calibrated micrometer.
• B: The tolerance is the allowed range, 22.00 to 22.10 mm, which is 0.10 mm wide and unrelated to the display step.
• C: With the micrometer 0.08 mm off, the true size could be 21.97 mm or 22.13 mm, both outside the range, so the reading cannot be trusted.
• D: Resolution is only the smallest step the instrument displays; accuracy depends on calibration.

Answer: D

Correct answer: 60 N·m. An in-line crowfoot makes the lever longer, so set the wrench lower than the spec.

• A: This uses the ratio upside down, (L + E)/L, which raises the setting and would overtighten the fastener.
• B: Setting the spec directly ignores that an in-line crowfoot lengthens the lever, so the fastener would get more than 72 N·m.
• C: This subtracts the crowfoot reach from the wrench length instead of adding it to the denominator.
• D (correct): Multiplying the spec by L/(L + E) = 0.30/0.36 lowers the setting to account for the longer effective lever.

Answer: A

Correct answer: 6 V. Series resistances add:

The drop across the 4 Ω resistor is

• A (correct): Total resistance is 8 Ω, so 1.5 A flows, and 1.5 A times 4 Ω gives 6 V across that resistor.
• B: This is the circuit current in amperes, not the voltage across the 4 Ω resistor.
• C: The full supply voltage is shared among all three resistors in a series circuit, not dropped across one of them.
• D: This splits 12 V equally three ways, but series resistors divide voltage in proportion to their resistance.

Answer: C

Correct answer: 0.11 mm. Total indicated runout equals maximum minus minimum:

Subtracting a negative reading adds it.

• A: This subtracts 0.05 from 0.06 and ignores that the low reading is on the negative side of zero.
• B: This is only the high reading; runout must include the swing below zero as well.
• C (correct): Runout is the full needle swing: 0.06 minus (-0.05) equals 0.11 mm.
• D: This averages the two readings instead of taking the full difference between them.

Answer: D

Correct answer: 120 lb-ft. Change the distance to feet first: 18 in divided by 12 = 1.5 ft. Then

-ft.

• A: This multiplies 80 by 18 inches but labels the result in pound-feet; 1,440 is pound-inches.
• B: This divides the force by the distance in feet instead of multiplying.
• C: This adds the force and the distance; torque is their product, not their sum.
• D (correct): Converting 18 in to 1.5 ft and multiplying by 80 lb gives 120 lb-ft.

Answer: B

Correct answer: 14.3 mm. Convert the fraction to a decimal,

then multiply by 25.4:

or about 14.3 mm.

• A: This divides by 25.4 instead of multiplying; to go from inches to millimeters you multiply.
• B (correct): Multiplying 0.5625 in by 25.4 mm per inch gives 14.2875 mm, which rounds to 14.3 mm.
• C: This divides 25.4 by 0.5625, which is not a valid conversion.
• D: This rounds to the nearest common metric wrench size; the true value is 14.3 mm, so a 14 mm wrench is not the same size.

Answer: B

Correct answer: Cabin air filter. Weak airflow and odors from the vents point to the cabin air filter, which cleans air entering the passenger compartment. The engine air filter is a separate part that affects engine performance.

• A: This filter feeds air to the engine; when clogged it affects engine performance, not vent airflow.
• B (correct): This filter cleans air entering the passenger compartment, and a clogged one causes weak vent airflow and odors.
• C: The oil filter cleans engine oil and has nothing to do with air delivered to the passenger compartment.
• D: The fuel filter cleans fuel going to the engine, not air for the heating and air-conditioning system.

Answer: A

Correct answer: Torque each bolt to 40 N·m in order, then use an angle gauge to add 90 degrees. This is torque-angle tightening. Bring each bolt to 40 N·m with a torque wrench in the specified pattern, then turn each one 90 degrees more, measured with an angle gauge, in the same order so the head clamps evenly.

• A (correct): Torque-angle tightening uses a torque wrench for the first stage and an angle gauge to measure the extra turn, following the set order.
• B: Degrees of rotation cannot be converted into an added torque figure; the procedure calls for a measured angle.
• C: An impact wrench gives no reliable torque, and estimating the angle by eye skips the measurement the procedure requires.
• D: Ignoring the listed sequence can clamp the head unevenly and warp it.

Answer: B

Correct answer: Seal it in a container and take it to a recycling site that accepts used oil. Used engine oil carries metals and other contaminants. Keep it unmixed, seal it in a container and take it to a place that accepts used oil for recycling.

• A: Used oil contains metals and contaminants and must never go into a drain, no matter how much water follows it.
• B (correct): Used oil is recyclable when kept clean and delivered to a collection point such as a recycling center or parts store.
• C: Mixing used oil with antifreeze or solvents can make it impossible to recycle.
• D: Spreading used oil on the ground contaminates soil and water.

Answer: A

Correct answer: Turned down to its lowest setting. A click-type wrench uses an internal spring to set the release point. Storing it at its lowest setting keeps the spring relaxed so the wrench holds its calibration.

• A (correct): Backing the setting off relieves the internal spring so it does not weaken and lose calibration.
• B: Keeping the spring compressed for long periods can weaken it and throw readings off.
• C: Maximum setting compresses the spring the most, which is the worst condition for storage.
• D: A torque wrench is a measuring tool and should not be used to break loose stuck fasteners.

Answer: B

Correct answer: Drill a centered pilot hole, then turn the extractor counterclockwise with steady force. An extractor goes into a centered pilot hole drilled in the broken shank. Its reverse threads bite when turned counterclockwise, backing the bolt out; penetrating oil and steady, gentle force keep the brittle extractor from breaking.

• A: Turning clockwise would tighten the broken bolt, and heavy force risks snapping the brittle extractor.
• B (correct): The reverse-threaded extractor bites as it turns counterclockwise and backs the broken shank out.
• C: Extractors need a centered pilot hole, and hard blows can crack the brittle tool inside the bolt.
• D: A shank broken flush leaves nothing for pliers to grip, and pliers are not meant to turn fasteners.

Answer: C

Correct answer: Leave it alone; only trained technicians following the disabling procedure may work on it. Bright orange cables on hybrid and electric vehicles carry high voltage, often several hundred volts. Routine maintainers should not touch them; only trained technicians with insulated gloves and the maker's procedure should work on that system.

• A: Disconnecting high-voltage cables without training and the maker's disabling procedure risks fatal shock.
• B: A 12-volt test light is not suited to high-voltage systems, and probing them is work for trained technicians only.
• C (correct): Orange cabling marks high-voltage parts that can cause fatal shock, so routine maintainers must not touch them.
• D: Ordinary cotton gloves give no protection from several hundred volts.

Answer: A

Correct answer: Puller. A puller grips the pulley with its arms or a plate and pushes against the shaft end with a center screw, drawing the part off evenly without hammer blows.

• A (correct): A puller uses arms or a plate and a center screw to draw the pulley off the shaft evenly.
• B: A center punch makes a small dimple to start a drill bit; it does not remove pressed-on parts.
• C: Hammering on a pressed-on pulley can crack it or damage the shaft.
• D: Diagonal cutters snip wire and cotter pins and cannot draw a part off a shaft.

Answer: C

Correct answer: 200 N. Use

and solve for F.

• A: This treats the pull as a right angle; at 30 degrees only half the force turns the bolt, so more force is needed.
• B: This multiplies by sin 30° instead of dividing by it, which gives less force when an angled pull actually needs more.
• C (correct): Solving 40 = 0.40 × F × sin 30° gives F = 40 / 0.20 = 200 N.
• D: This uses cos 30° instead of sin 30°; the turning part of the force depends on the sine of the angle to the handle.

Answer: C

Correct answer: 1.0 Ω. Ohm's law gives the total resistance:

Subtract the bulb:

of extra resistance, such as from a corroded connection.

• A: This is the total resistance of the whole circuit, including the bulb, not the extra resistance alone.
• B: This is the bulb's own resistance; the question asks for what the wiring adds beyond it.
• C (correct): The circuit's total resistance is 12.0 / 3.0 = 4.0 Ω, and 4.0 minus the 3.0 Ω bulb leaves 1.0 Ω of extra resistance.
• D: This divides current by voltage, which flips Ohm's law; resistance equals voltage divided by current.

Answer: D

Correct answer: The fluid absorbs moisture from the air, which lowers its boiling point. Brake fluid absorbs moisture from the air. That water lowers its boiling point, so keep the container sealed and use only the type listed on the reservoir cap.

• A: Brake fluid does not flash off quickly; the main concern with an open container is moisture absorption.
• B: Exposure to air does not thicken brake fluid; the problem is the water it absorbs.
• C: Carbon monoxide comes from engine exhaust, not from brake fluid in a container.
• D (correct): Water picked up from the air lets the fluid boil at a lower temperature under hard braking, reducing braking performance.