Basic Symptom Diagnosis Lesson Test

Answer: A

Correct answer: The starter spins the engine at normal speed, but the engine never runs on its own. Crank-no-start means the starter turns the engine at normal speed, yet the engine never begins running by itself. That points away from the starting circuit and toward fuel, spark, air or engine control.

• A (correct): Crank-no-start means the starting circuit works but the engine lacks fuel, spark, air or proper control.
• B: An engine that runs, even briefly, has started; this is a stalling complaint.
• C: A single click with no cranking is a no-crank symptom, not crank-no-start.
• D: That describes a no-crank condition, which points to the starting circuit.

Answer: B

Correct answer: The anti-lock function may be disabled, though normal braking usually remains. An amber ABS lamp means the anti-lock function may be off, although ordinary braking usually remains. A red brake lamp is the one that can signal low fluid, a hydraulic fault or an applied parking brake.

• A: Low fluid or a hydraulic fault is signaled by the red brake lamp, not the amber ABS lamp.
• B (correct): The amber ABS lamp concerns the anti-lock system; base hydraulic braking normally still works.
• C: A parking brake that is on lights the red brake warning, not the ABS lamp.
• D: Low tire pressure is signaled by the TPMS lamp.

Answer: C

Correct answer: Oil burning in the cylinders. Blue-gray smoke suggests oil is burning in the cylinders. Black points to a rich fuel mixture and persistent sweet white smoke to coolant, but color only guides the search; it does not name the failed part.

• A: Coolant typically produces thick white, sweet-smelling smoke.
• B: Condensation appears as thin white vapor that clears as the engine warms.
• C (correct): Blue-gray smoke is the classic sign of engine oil being burned.
• D: That is the usual meaning of black smoke.

Answer: B

Correct answer: Stop safely and arrange qualified service. A brake pedal that sinks or feels spongy usually means the hydraulic system is not building normal pressure, from causes such as a fluid leak, air in the lines, or a failing master cylinder. Since stopping distance can grow suddenly and unpredictably, the safe priority is to pull over where it is safe, use low gears and the parking brake if needed, and have the vehicle towed or inspected. Continuing to drive to test the brakes risks a crash.

• A: Washer fluid does not restore brake hydraulic integrity.
• B (correct): Correct: braking performance must not be assumed.
• C: Road testing uncertain stopping ability is hazardous.
• D: More speed increases risk, and heat does not restore a soft pedal or safely diagnose brakes.

Answer: B

Correct answer: A thermostat stuck open. The thermostat should stay closed while the engine warms and open afterward. If it is stuck open, coolant is cooled by the radiator the whole time, so warm-up is slow and the heater stays weak.

• A: A thermostat stuck closed traps heat and tends to cause quick overheating, not slow warm-up.
• B (correct): If it stays open, coolant flows to the radiator from the start, so the engine warms slowly and heater output is weak.
• C: A slipping belt affects charging and may squeal, but it does not explain slow engine warm-up.
• D: A fan that fails to run would make the engine run hot in slow traffic, not cool.

Answer: A

Correct answer: Evidence identifying a monitored fault area to investigate. An on-board diagnostic system sets a trouble code when a monitored value falls outside its expected range under certain conditions. The code tells you which circuit or system disagreed with expectations, not which part failed. For example, an oxygen-sensor code might come from the sensor, its wiring, an exhaust leak or a fuel-mixture problem. Technicians use the code as a starting point, then test to confirm the cause before replacing anything.

• A (correct): Correct: it guides diagnosis, not automatic part replacement.
• B: Monitoring can cover only specific conditions and systems.
• C: A code alone cannot determine the required replacement.
• D: Codes can reflect circuitry, control, and operating conditions, not just the named sensor.

Answer: A

Correct answer: Check tire pressures safely against the vehicle placard. Under U.S. rules, the TPMS lamp lights when a tire falls well below its recommended cold pressure, roughly 25 percent low. The right response is to stop somewhere safe, inspect the tires, and measure each one with a gauge, comparing the readings to the door placard, not the sidewall maximum. Correcting the pressure and then watching whether the lamp resets also helps reveal a slow leak or puncture.

• A (correct): Correct: confirm cold pressures with a suitable gauge and placard values.
• B: TPMS warns; it cannot inflate or repair a tire.
• C: Alignment does not establish air pressure.
• D: Sidewall maximum is not the specified routine pressure.

Answer: C

Correct answer: A potentially serious lubrication-system concern. The oil-pressure lamp lights when the pressure switch senses that oil is not being pumped to bearings and other moving parts at the needed pressure. Without that oil film, metal surfaces rub directly, and serious engine damage can follow within minutes. The safe response is to stop and shut off the engine as soon as safely possible, then check the oil level. Do not confuse it with an oil-change reminder, which only signals a maintenance interval.

• A: Tire pressure is a different monitoring system.
• B: Oil condition is not certified by the pressure warning.
• C (correct): Correct: engine damage can occur if required oil pressure is lost.
• D: Vehicle cleaning has nothing to do with oil pressure.

Answer: C

Correct answer: Rough engine idle while stopped. A useful diagnostic habit is to sort symptoms by what they depend on. Anything tied to wheel rotation, such as tire hum or speed-dependent shake, disappears when the vehicle is not moving. A rough idle comes from the engine itself, often from a misfire, vacuum leak or worn engine mounts, so it can occur while the car is parked. If a symptom appears at zero road speed, wheels and tires can usually be ruled out.

• A: Tire hum requires wheel motion in this stated scenario.
• B: That explicitly depends on moving road speed.
• C (correct): Correct: a running engine can idle roughly while stationary.
• D: A zero-speed vehicle has no highway-speed tire rotation.

Answer: A

Correct answer: Prevent wheel lock during certain braking events. A locked, skidding tire has less grip than a rolling one and cannot steer the car. ABS uses wheel-speed sensors to detect a wheel that is about to lock, then a hydraulic modulator rapidly releases and reapplies pressure to that brake, many times per second, so the tire keeps rolling near the limit of traction and the driver keeps steering control. ABS has nothing to do with charging the battery, moving coolant or measuring oil.

• A (correct): Correct: ABS modulates brake pressure to help maintain traction and steering control.
• B: ABS does not measure lubricant viscosity.
• C: The charging system restores electrical energy.
• D: The cooling system moves coolant; ABS has no role in it.

Answer: A

Correct answer: 360 W. Use

for each load: blower

W and defroster

Together they draw

the same as $12\times 30$.

• A (correct): The blower uses 12 × 12 = 144 W and the defroster 12 × 18 = 216 W, for 360 W total.
• B: This divides the total current by the voltage instead of multiplying.
• C: This adds the currents but never multiplies by voltage, so the result is in amperes, not watts.
• D: This is only the defroster's power (18 A × 12 V); the blower adds its own 144 W.

Answer: D

Correct answer: 0.54 V. A bad connection acts like a small series resistor.

V is lost at the clamp before current reaches the starter.

• A: This squares the current (180² × 0.003), which gives the heat power in watts, not the voltage drop.
• B: This divides current by resistance; the drop is current multiplied by resistance.
• C: This misplaces the decimal, treating the resistance as 0.03 $\Omega$.
• D (correct): The drop is 180 A × 0.003 $\Omega$ = 0.54 V, voltage the starter never receives.

Answer: D

Correct answer: 88 ft. Convert the speed:

/s. Then

• A: This multiplies mph by seconds without converting the speed to feet per second.
• B: This uses 88 ft/s, the speed at 60 mph, rather than 44 ft/s at 30 mph.
• C: This divides the speed by the time instead of multiplying.
• D (correct): 30 mph equals 30 × 5280 ÷ 3600 = 44 ft/s, and 44 × 2 = 88 ft.

Answer: B

Correct answer: Whether the starting conditions, such as brake pedal applied and Park selected, were met. This is a no-crank, so the starting circuit and its controls come first. Push-button systems usually require the brake pedal to be pressed and the transmission in Park or Neutral, so confirming those conditions is the quickest, least intrusive check before testing parts.

• A: Condemning the starter skips a simple interlock check that matches the exact conditions described.
• B (correct): Many push-button cars block the starter unless the brake is pressed and the shifter is in Park or Neutral, so this free check comes first.
• C: The alternator charges the system once the engine runs; it plays no part in a starter that is not being allowed to engage.
• D: Fuel matters for a crank-no-start; here the engine does not turn at all, which points to the starting circuit and its controls.

Answer: D

Correct answer: Whether the vibration follows engine rpm rather than road speed. A strong first step in diagnosing vibration is to find what it follows. If the vibration changes as you raise engine rpm in park or neutral, its source is likely in the engine or its accessories and mounts. If it changes with vehicle speed regardless of rpm, look at wheels, tires and driveline. Since this rough idle occurs only while stationary, road-speed parts such as tires and axles are unlikely causes.

• A: Paint has no stated mechanical connection.
• B: Sidewall inflation data cannot isolate rough idle.
• C: Axle ratio is irrelevant while not moving in this scenario.
• D (correct): Correct: speed association separates some engine and wheel hypotheses.

Answer: C

Correct answer: The monitored circuit or condition requires additional diagnosis. A sensor-related code means the control module saw a signal that did not make sense, such as a voltage out of range or a value inconsistent with other readings. That signal passes through the sensor, connectors, wiring and the module itself, and the engine condition being measured could also be abnormal. Testing those pieces before buying parts prevents replacing a good sensor when the real problem is a corroded connector or damaged wire.

• A: Wiring or operating conditions can generate the monitored fault, so replacing the sensor first is premature.
• B: A DTC does not guarantee readiness status.
• C (correct): Correct: codes narrow investigation, not the exact repair.
• D: Compression cannot be inferred from that code alone.

Answer: A

Correct answer: Useful fault-context data may be lost and monitors may reset. When a code sets, the computer also stores freeze-frame data: a snapshot of conditions such as engine speed, coolant temperature, load and fuel trim at that moment. This helps a technician reproduce and understand the fault. Clearing codes erases that snapshot and resets readiness monitors, which then must rerun through specific driving cycles. That is why the standard practice is to record codes and freeze-frame data before clearing anything.

• A (correct): Correct: freeze frame and readiness can be affected by a reset.
• B: Clearing data does not inflate tires.
• C: Code clearing does not chemically contaminate engine oil.
• D: Clearing codes cannot mechanically change toe or camber.

Answer: D

Correct answer: 132 ft. First find the deceleration:

Then

• A: This is the deceleration in ft/s², not a distance.
• B: This divides the speed squared by the time instead of by twice the deceleration.
• C: This multiplies the starting speed by the time, ignoring that the car slows down the whole way.
• D (correct): Deceleration is 66 ÷ 4 = 16.5 ft/s², and 66² ÷ (2 × 16.5) = 132 ft.

Answer: B

Correct answer: Inspect drive belt condition and tension with the engine off. A squeal when accessories add load often means the drive belt is slipping. Because that belt turns the alternator, slippage can also trigger the charging lamp, so the belt's condition and tension are inspected first, with the engine off.

• A: The lamp flags the charging system, not a specific part; replacing parts before simple checks skips the evidence.
• B (correct): A squeal under added load suggests belt slip, which can also cut alternator output; checking the belt is quick and safe.
• C: Clearing codes erases evidence and does nothing to fix a slipping belt.
• D: The battery-shaped lamp is a charging-system warning, not a battery-condition verdict.

Answer: A

Correct answer: Pressure loss can threaten engine lubrication immediately. Oil pressure is what forces oil between bearings and moving surfaces; without it, metal rubs on metal and parts can be damaged within minutes. The pressure lamp therefore calls for stopping safely and shutting the engine off. An oil-service reminder is just a maintenance timer based on mileage, time or operating conditions, and it can wait for a convenient appointment. Treating the red pressure warning like a routine reminder is the dangerous mix-up.

• A (correct): Correct: insufficient oil pressure may quickly damage engine components.
• B: Tread depth is unrelated.
• C: Illumination is not the safety significance.
• D: Maintenance interval reminders do not imply brake failure.

Answer: B

Correct answer: Wheel/tire imbalance or rotating assembly condition. When a vibration appears at a specific road speed, regardless of engine rpm, the source is usually something that turns with the wheels. A wheel imbalance acts like a small rotating weight, and it often becomes most noticeable within a certain speed range where it excites the suspension and steering. Felt in the steering wheel, it points toward the front wheels. Engine-related problems, by contrast, tend to follow rpm and appear at idle too.

• A: Plug appearance is not the main discriminating feature.
• B (correct): Correct: road-speed association is a clue toward rotating components.
• C: Fuel quality is not the only explanation for speed-linked steering vibration, and it is an unlikely one.
• D: Trim fabric does not produce the described rotating-force pattern.

Answer: D

Correct answer: Tire inflation, road crown and brake drag. Several tire, road and brake factors can cause a pull.

• A: A cabin filter affects ventilation, not chassis alignment.
• B: Oil grade and service timing are not a direct explanation for steering pull.
• C: Fuel octane and brand do not change wheel geometry.
• D (correct): Correct: uneven tire pressure, a sloped road surface or a dragging brake can each cause a pull.

Answer: A

Correct answer: Normal ABS pressure modulation in that context. During hard braking, ABS rapidly releases and reapplies brake pressure at any wheel that starts to lock. Those quick pressure changes push back through the hydraulic system, so the driver feels pulsing in the pedal and may hear buzzing or grinding from the ABS unit. This is normal; keep firm pressure on the pedal and steer. A pulsation during ordinary gentle stops, without ABS activity, points more toward a brake rotor problem.

• A (correct): Correct: the context of ABS intervention matters.
• B: Coolant does not cause ABS-modulation pulsation.
• C: Electrical short diagnosis cannot be made from pedal vibration.
• D: Pulsation during active ABS is not sufficient evidence for new rotors.

Answer: D

Correct answer: Check tires with a gauge when cold. The TPMS lamp stays off until pressure drops a set amount, often about 25 percent below the placard value, so tires can be low enough to affect handling and wear without any warning. Checking monthly with a gauge, before driving or after the vehicle has sat for a few hours, gives accurate cold readings to compare with the door placard. Think of TPMS as a smoke alarm, not a substitute for routine inspection.

• A: TPMS has warning thresholds and does not replace maintenance.
• B: No failed sensor has been established.
• C: Maximum marking is not ordinary recommended inflation.
• D (correct): Correct: cold-gauge measurements against vehicle recommendations remain useful.

Answer: C

Correct answer: Investigate the braking system, but keep related wheel causes in view. Good diagnosis changes one condition at a time and watches how the symptom responds. If vibration appears only when the brakes are applied, the braking system becomes the main suspect, with uneven rotor thickness or rotor runout being common causes. However, rotors sit on the hubs, so a bent wheel, loose lug nuts or worn wheel bearings can also show up during braking. Narrowing the search without ruling out connected parts avoids misdiagnosis.

• A: Wheel/tire conditions cannot be completely excluded.
• B: TPMS sensor replacement is unrelated to the observation.
• C (correct): Correct: changing a single operating condition is useful evidence.
• D: Brake-onset vibration does not guarantee ignition failure.

Answer: C

Correct answer: Normal A/C condensation draining from the vehicle. The A/C pulls moisture out of cabin air and drains it as clear, odorless water, usually near the passenger side of the firewall. With an unchanged coolant level, this is normal condensation, not a leak.

• A: Coolant is usually colored, slightly slick and sweet-smelling, and its reservoir level would drop.
• B: An internal leak lowers the coolant level and would not leave clear water under the car.
• C (correct): Clear, odorless water near the passenger-side firewall with a steady coolant level fits normal A/C drainage.
• D: Brake fluid is oily and would lower the brake reservoir; it does not drip as clear water after A/C use.

Answer: A

Correct answer: The root cause may persist despite the lamp clearing. Erasing codes simply wipes the computer's memory and turns off the warning light; it does not repair anything. If the fault remains, such as a misfire or leaking evaporative system, the monitor that found it will detect it again during later driving and the lamp will return. Clearing codes also resets readiness monitors, which can cause a vehicle to fail an emissions inspection until they complete. A fix is confirmed only by repairing and retesting.

• A (correct): Correct: the underlying condition may return when monitors run.
• B: Erasure is not repair confirmation.
• C: A cleared lamp does not test fuel.
• D: Resetting diagnostic memory does not restore compression.

Answer: B

Correct answer: About 10. Circumference is

or about 6.54 ft. Each second the car covers 66 ft, so the tire turns

times per second.

• A: This divides by the 25 in diameter (about 2.08 ft) instead of the circumference.
• B (correct): Circumference is $\pi$ × 25 ≈ 78.5 in ≈ 6.54 ft, and 66 ÷ 6.54 ≈ 10 turns per second.
• C: This divides feet per second by the diameter in inches, mixing units.
• D: This divides feet per second by the circumference in inches without converting to feet.

Answer: D

Correct answer: One side is likely braking harder, so the brakes should be inspected first. Because the pull happens only when braking, the likely cause is uneven braking force from side to side, such as a sticking caliper, contaminated pads or a hose problem. Inspect the brakes first while keeping tires and suspension in view.

• A: A misfire causes shaking tied to engine rpm, not a sideways pull during braking.
• B: Imbalance causes a speed-related shake, not a pull that appears only during braking.
• C: A misalignment would usually cause a pull or drift while cruising too, not only during braking.
• D (correct): A pull that appears only when braking points to uneven braking force, such as a sticking caliper or contaminated pads.

Answer: C

Correct answer: Remove it from service and arrange qualified assistance. Exposed cords mean the rubber that protects the tire's internal reinforcement has worn or torn through. The cords carry the load and hold the air, so the tire can fail suddenly, especially when hot or at high speed. Safety takes priority over diagnosis: stop driving on it, install the spare if safe, or have the vehicle towed. Adding pressure or patching the outside cannot restore strength to damaged reinforcement.

• A: High-speed tests may provoke tire failure.
• B: Excess pressure cannot repair exposed reinforcement.
• C (correct): Correct: visible structural damage is a safety concern.
• D: Tape cannot restore structural integrity.

Answer: C

Correct answer: 9.8 V. First find the voltage lost inside the battery, then subtract it from the rest voltage.

• A: This ignores internal resistance; a large current always pulls terminal voltage below the resting value.
• B: This is the voltage lost inside the battery, not the voltage left at the terminals.
• C (correct): The internal drop is 180 A times 0.015 ohm, or 2.7 V, and 12.5 V minus 2.7 V leaves 9.8 V.
• D: This adds the internal drop to the rest voltage; voltage lost inside the battery lowers the terminal voltage.

Answer: D

Correct answer: 200 W. Heat lost in a resistance is found with

That heat is why a bad terminal can feel hot after cranking, and it also means the starter is losing voltage.

• A: The decimal is misplaced by three places; 40,000 times 0.005 is 200, not 0.2.
• B: Current times resistance gives the voltage drop (1 V), not the power; power uses current squared times resistance.
• C: This squares the current but forgets to multiply by the 0.005-ohm resistance.
• D (correct): Power lost as heat is current squared times resistance: 200 squared times 0.005 equals 200 W.

Answer: B

Correct answer: 225 ft. With constant deceleration, braking distance is proportional to speed squared. The speed ratio is

so the distance factor is

• A: This treats braking distance as proportional to speed; it actually grows with the square of speed.
• B (correct): Speed tripled, and braking distance grows with the square of speed, so 25 ft times 9 gives 225 ft.
• C: This squares the 25 ft distance instead of squaring the speed ratio of 3.
• D: This multiplies by 6 rather than by the speed ratio squared, which is 9.

Answer: D

Correct answer: 110 ft. Convert the speed to feet per second, then multiply by the time.

• A: This divides the speed by the time instead of multiplying them.
• B: This uses 88 ft/s, which is the conversion for 60 mph, not 50 mph.
• C: This multiplies 50 by 1.5 without converting miles per hour to feet per second.
• D (correct): 50 mph is about 73.3 ft/s, and 73.3 ft/s times 1.5 s equals 110 ft.

Answer: C

Correct answer: Electric cooling fan operation and radiator airflow. The fault appears only when road airflow is missing. At highway speed, air rushing through the radiator removes heat; in stop-and-go traffic the fan must do that job, so fan operation and clean radiator fins are the next checks, with hands kept clear since the fan can start on its own.

• A: Naming an expensive internal part skips the evidence; the speed-dependent pattern and normal coolant level point first to airflow.
• B: A thermostat stuck open makes the engine warm up slowly and run cool; it does not cause overheating at low speed.
• C (correct): At highway speed, moving air cools the radiator; in slow traffic the fan must supply airflow, so a fan or blocked-fin problem matches the pattern.
• D: Oil pressure relates to lubrication, not to a coolant temperature rise that depends on vehicle speed.

Answer: D

Correct answer: Possible coolant entering combustion; get professional testing. Thin white vapor on a cold morning is often condensation, but thick white smoke that persists after warm-up and smells sweet suggests coolant is being burned. A dropping reservoir with no visible leak supports an internal leak, which calls for professional testing before naming a part.

• A: Condensation is thin vapor on cold starts; persistent thick, sweet-smelling smoke after warm-up with coolant loss is not normal.
• B: Burning oil gives blue-gray smoke and does not explain a falling coolant level.
• C: A rich mixture produces black smoke, not sweet-smelling white smoke with coolant loss.
• D (correct): Thick, sweet, persistent white smoke plus coolant loss without external leaks suggests an internal leak that needs proper testing.

Answer: B

Correct answer: Load-test or conductance-test the battery. A 12.6 V resting reading only shows the battery is charged, and bright headlights draw very little current. Slow cranking with sharp dimming means voltage collapses under heavy load, which an aging battery can do, so a load or conductance test is the evidence needed before blaming any other part.

• A: Headlights draw only a few amps, while the starter draws over 100 A, so bright lamps prove little about cranking ability.
• B (correct): A full resting voltage shows charge, not the ability to deliver high current; a load or conductance test checks real cranking capacity.
• C: The resting reading shows the battery is being charged; nothing yet points to the alternator, and the starting load test comes first.
• D: Resting voltage does not prove the battery can supply starter current, and the sharp dimming points to voltage collapsing under load.

Answer: C

Correct answer: Reduce engine load and have the vehicle checked promptly for a misfire. A steady check-engine lamp means have it checked soon, but a flashing lamp usually signals a severe misfire. Unburned fuel can overheat and damage the catalytic converter, so the driver should reduce load and have the misfire diagnosed promptly.

• A: Clearing codes erases freeze-frame data and repairs nothing; the misfire would continue and the lamp would return.
• B: A flashing lamp is more urgent than a steady one, so waiting risks damage to the catalytic converter.
• C (correct): A flashing lamp usually means a severe misfire that can overheat the catalytic converter, so ease the load and get it diagnosed soon.
• D: A maintenance reminder is a separate message; a flashing MIL warns of an active, severe fault.

Answer: A

Correct answer: A monitored condition may not yet be confirmed; record evidence and diagnose further. Many monitors require a fault to appear on two separate drive cycles before the check-engine light is lit. After the first detection, the system stores a pending code without lighting the MIL. A pending code is an early clue that something may be wrong, or it may have been a one-time event. The best approach is to record the code and freeze-frame data, check the related system, and watch whether it matures.

• A (correct): Correct: pending codes need context; MIL behavior is monitor-dependent.
• B: Pending status does not prove a named part is defective.
• C: Erasing codes can remove freeze-frame data and other useful evidence.
• D: Pending status does not indicate monitor completion.

Answer: B

Correct answer: Inspect for clutch/drivetrain slip while excluding other factors. In a manual transmission, the clutch disc is clamped between the flywheel and pressure plate so engine torque reaches the wheels. If the clutch is worn, oil-soaked or poorly adjusted, the engine can speed up while the disc slips, so rpm rises without a matching increase in road speed. That pattern strongly suggests slip, but a careful technician confirms it with tests, since other drivetrain issues can look similar.

• A: TPMS tracks pressure and cannot explain torque transfer.
• B (correct): Correct: mismatch supports evaluating power transmission, not certainty of one part.
• C: Charging voltage is not established by a speed mismatch.
• D: Rpm/road-speed mismatch cannot validate an oil sensor.

Answer: B

Correct answer: The starting circuit. An engine that does not turn over at all is a no-crank condition. No-crank points to the starting circuit: battery charge, cables and connections, starter-control interlocks and the starter itself. Fuel, spark and air come into play only once the engine cranks but will not run.

• A: Fuel problems leave the engine cranking but not running; they cannot stop the engine from turning over.
• B (correct): When the engine does not turn over, the battery, cables, interlocks and starter that make it rotate are the logical place to begin.
• C: Missing spark causes a crank-no-start, where the engine still spins; it does not prevent rotation.
• D: Cooling problems cause overheating while running and have nothing to do with the engine refusing to turn.

Answer: C

Correct answer: 2 Ω. Use

• A: This multiplies voltage by current; Ohm's law divides voltage by current to get resistance.
• B: This divides current by voltage, which inverts the formula.
• C (correct): Resistance equals voltage divided by current: 12 V divided by 6 A is 2 ohms.
• D: This subtracts the current from the voltage; volts and amps cannot be subtracted to give ohms.

Answer: C

Correct answer: 0.015 Ω. The terminal voltage equals the resting voltage minus the internal drop, so first find the drop: 12.4 V minus 10.0 V is 2.4 V.

Then rearrange the drop formula

to solve for resistance.

• A: This divides the cranking voltage by the current; the internal resistance depends only on the voltage lost, not the voltage remaining.
• B: This divides the resting voltage by the current, ignoring that most of that voltage still reaches the terminals.
• C (correct): The voltage lost inside is 12.4 minus 10.0, or 2.4 V, and 2.4 V divided by 160 A is 0.015 ohm.
• D: This divides current by the voltage drop, which inverts Ohm's law.

Answer: B

Correct answer: Check whether the fuel pump primes and scan for codes. Normal cranking clears the starting circuit, so the problem is in what the engine needs to run: fuel, spark, air and engine control. Listening for the pump to prime and reading stored codes are quick, noninvasive checks that eliminate branches before any part is replaced.

• A: The starter is already spinning the engine at normal speed, so the starting circuit has done its job.
• B (correct): A crank-no-start points to fuel, spark, air or engine control, and a gauge reading does not prove that fuel is actually being delivered under pressure.
• C: Fuel quantity in the tank says nothing about whether the pump runs, the filter flows or the injectors are commanded.
• D: The battery is already charged and cranking is normal, so charging it again gathers no new evidence.

Answer: C

Correct answer: The charging system may not be keeping up. The battery lamp normally goes out once the engine runs, because the alternator takes over. If it lights while driving, the charging system (belt, alternator, wiring or connections) may not be supplying enough current. It identifies a system to test, not a single failed part.

• A: The lamp flags a charging-system problem, not the age of the battery.
• B: Oil pressure has its own red oil-can lamp; the battery icon concerns electrical charging.
• C (correct): With the engine running the alternator should supply the electrical load; the lamp warns that charging may have dropped out.
• D: The lamp warns that charging may be insufficient, not that a long trip has overfilled the battery.

Answer: D

Correct answer: Clean and tighten the battery terminals. Corrosion on the posts acts like extra resistance in series with the starter, so less current reaches it and the engine cranks slowly even though the battery is charged. Cleaning and tightening the connections is the least intrusive first step; test further only if the slow crank remains.

• A: A slow crank with heavy corrosion on the posts has not yet been traced to the starter, so this skips the cheap evidence.
• B: The battery shows full charge; the visible problem is in the connections, not its size.
• C: A jump start may get the truck going but leaves the high-resistance connection in place.
• D (correct): Corrosion adds resistance that limits starter current, and cleaning and tightening is a quick, low-cost check that may fix it.

Answer: B

Correct answer: 275 ft. Convert the speed:

/s.

Then use distance equals speed times time.

• A: This multiplies 75 by 2.5 without converting miles per hour into feet per second.
• B (correct): 75 mph is 110 ft/s, and 110 ft/s times 2.5 s is 275 ft.
• C: This uses 88 ft/s, which is the conversion for 60 mph, not 75 mph.
• D: This divides the speed by the time instead of multiplying them.

Answer: C

Correct answer: 147 ft. Braking distance is proportional to the square of speed. The speed ratio is

• A: This scales distance in direct proportion to speed, but braking distance grows with the square of speed.
• B: This simply doubles the distance; the speed ratio is 1.75, and its square, not 2, sets the new distance.
• C (correct): The speed ratio is 70/40 = 1.75, and 1.75 squared is about 3.06, so 48 ft times 3.0625 is 147 ft.
• D: This applies the four-times rule for doubled speed, but 70 mph is not double 40 mph.

Answer: A

Correct answer: 22 ft/s². Use

The speed changes by 88 ft/s over 4 s.

• A (correct): Deceleration is the speed change divided by the time: 88 ft/s divided by 4 s is 22 ft/s squared.
• B: This multiplies speed by time, which gives a distance-like number, not a rate of slowing.
• C: This divides time by speed, which inverts the formula.
• D: This divides by 2 times the time, mixing in the 2 from the stopping-distance formula where it does not belong.

Answer: C

Correct answer: 67.5 W. First find the connection's resistance:

Then find the heat power.

As a check, voltage drop times current gives the same result:

• A: This puts the 0.45 V drop into $I^{2}R$ as if it were the resistance; the resistance is only 0.003 ohm.
• B: This divides current by voltage, which does not give power.
• C (correct): The resistance is 0.45 V divided by 150 A, or 0.003 ohm, and $150^2\times 0.003$ is 67.5 W, the same as 0.45 V times 150 A.
• D: This is the connection's resistance in ohms, found by stopping after the first step instead of going on to power.

Answer: A

Correct answer: Alternator. The battery supplies the burst of energy needed for cranking. After the engine starts, the belt-driven alternator powers the vehicle's electrical loads and recharges the battery, which is why running voltage is normally about 13.5 to 14.7 V.

• A (correct): The engine-driven alternator takes over the electrical load once the engine runs and recharges the battery.
• B: The starter only cranks the engine and stops working once the engine runs.
• C: The coil produces high voltage for spark plugs; it does not charge the battery.
• D: A resistor uses up voltage; it cannot produce electrical energy.

Answer: A

Correct answer: Lamps draw only a few amps, while a starter can draw over 100 A. Lighting circuits need only a few amps, but cranking can require well over 100 A. A weak battery or a poor connection can keep lamps bright and still fail under starter load, so a load test or a voltage reading during cranking is needed.

• A (correct): A battery or cable can light bulbs well yet collapse under the far larger cranking load, so bright lamps prove only that some power is present.
• B: With the engine off, the headlights are powered by the battery, so they do reflect the battery to some degree.
• C: A typical car uses a single 12 V battery for both lighting and starting.
• D: Bright lamps do not show overcharging; they just show that the battery can support a small load.

Answer: D

Correct answer: The charging system is not keeping up and should be tested. A healthy running system should raise battery voltage to roughly 13.5 to 14.7 V. Here running voltage stays near the 12.5 V resting value and falls as loads are added, so the charging system is not supplying the demand. Inspect the belt and connections, then perform a charging-system test, even though no lamp is lit.

• A: A rise of only 0.1 V is far below the roughly 13.5 to 14.7 V expected from a working charging system.
• B: A 12.5 V resting reading shows a charged battery; the readings point at charging, not at the battery itself.
• C: Nothing in the readings suggests the starter is engaged; low running voltage is a charging-system sign.
• D (correct): Running voltage that stays near resting voltage and drops under load means the alternator, belt or wiring needs checking.

Answer: C

Correct answer: Stop safely and have the brake system checked. A red brake lamp can mean the parking brake is on, fluid is low or the hydraulic system has a fault. Once the parking brake is ruled out, the remaining causes affect stopping ability, so the safe choice is to stop and have the brakes inspected.

• A: The red lamp concerns the base hydraulic brakes, not the anti-lock function, so it cannot be ignored.
• B: Road-testing a suspect brake system risks a crash; the lesson calls for stopping safely instead.
• C (correct): With the parking brake released, the red lamp can mean low fluid or a hydraulic fault, so the vehicle should be checked before further driving.
• D: Clearing a warning does not fix low fluid or a hydraulic problem and removes evidence.

Answer: A

Correct answer: The freeze-frame data saved with the code. When a code sets, the computer saves a freeze-frame snapshot that includes coolant temperature, engine speed, vehicle speed and load. Reading it shows whether the fault happened cold or warm, which is why it should be recorded before codes are cleared.

• A (correct): Freeze-frame data record values such as coolant temperature, rpm and vehicle speed at the moment the code set.
• B: Readiness monitors show whether self-tests have run, not the conditions when a fault occurred.
• C: Recall status is a separate clue and records nothing about this particular fault event.
• D: A maintenance reminder tracks time or mileage for service, not engine conditions.

Answer: D

Correct answer: The computer's own tests confirming the repair. A permanent code cannot be erased with a scan tool or by removing power. It clears itself only after the engine computer runs its own tests under the needed driving conditions and confirms that the fault is fixed.

• A: Permanent codes are designed to survive power loss as well as scan-tool clearing.
• B: No scan tool can erase a permanent code; that is what makes it permanent.
• C: A part swap alone does not clear the code; the computer must still verify the repair.
• D (correct): A permanent code clears only after the computer reruns its monitors and finds the fault gone.

Answer: B

Correct answer: Leave them alone for trained technicians. Hybrid and electric vehicles carry high-voltage batteries and cables, usually with orange insulation, that can deliver a lethal shock. Basic diagnosis covers conventional 12 V systems only, so orange cables and high-voltage parts are left to trained technicians.

• A: Handling high-voltage cables can cause a lethal shock; they are not for home checks.
• B (correct): Orange insulation marks high-voltage parts, which should be handled only by trained technicians using the manufacturer's procedures.
• C: A 12 V test light is not rated for high-voltage systems and puts the user at risk.
• D: Disconnecting high-voltage cables is dangerous and requires special procedures and protective equipment.

Answer: D

Correct answer: Stop safely and have the power-assist system checked. Sudden heavy steering can come from a broken power-assist belt, low hydraulic fluid or an electric assist fault, and the squeal-then-silence pattern fits a belt that slipped and came off. Because steering affects control, slow down, stop safely and have it checked rather than continuing.

• A: Heavy steering reduces control, especially in an emergency maneuver, so driving on is unsafe.
• B: A squeal followed by heavy steering points to the drive belt and power assist, not engine oil.
• C: No evidence yet links the problem to the rack; buying parts first skips the inspection.
• D (correct): The sounds and heavy steering suggest a lost assist belt or assist fault, which affects control and needs inspection.

Answer: C

Correct answer: Normal condensation clearing as the exhaust warms. Thin white vapor on a cold morning is usually water condensing in a cold exhaust, and it stops once the system warms. Coolant entering combustion would give thick, sweet-smelling smoke that persists when hot and a dropping reservoir level, so the evidence here points to a normal condition.

• A: Coolant burning gives thick, sweet-smelling white smoke that persists when warm, along with falling coolant level, none of which is present here.
• B: Burning oil gives blue-gray smoke that does not clear up as the engine warms.
• C (correct): Thin vapor on a cold morning that fades with warm-up, with no odor and steady coolant, fits ordinary condensation.
• D: Excess fuel produces black smoke, not thin white vapor that clears with warm-up.

Answer: D

Correct answer: A coolant leak; inspect and check the level when cold. Coolant is often orange, green, pink or blue and smells sweet, and a coolant leak lowers the reservoir level. Look for the highest wet point around the pump and hoses, and check the level only when the engine is cold, since a hot system can spray scalding coolant.

• A: A/C drain water is clear and odorless, and it does not lower the coolant reservoir.
• B: Engine oil is not orange or sweet smelling, and a dropping coolant tank points to the cooling system.
• C: Brake fluid is not found near the water pump, and the falling coolant level points to the cooling system instead.
• D (correct): Colored, sweet-smelling fluid near the water pump plus a falling reservoir level points to coolant, and the level must be checked only with the engine cold.

Answer: D

Correct answer: Test power, control and connections at the starter. A single click with bright lights and a charged battery is a no-crank that points beyond the battery to the starter circuit. Since the clutch was pressed and the terminals are good, measure power and control at the starter and check its cable connections before deciding the starter itself has failed.

• A: The battery is charged, the lights stay bright, and the terminals are good, so nothing points to the battery yet.
• B: The engine is not turning at all, so this is a no-crank; fuel matters only after the engine cranks.
• C: Erasing codes removes evidence and does nothing to explain a single click.
• D (correct): With a good battery and the clutch interlock satisfied, the next link is whether the starter receives power and its control signal while the key is turned.

Answer: B

Correct answer: The pads are close to the end of their life. Many brake pads carry a small metal tab that touches the rotor and squeals when the pad is nearly worn out. It is a warning to inspect and replace the pads soon, before metal-to-metal grinding damages the rotor.

• A: ABS action is felt as pedal pulsing during hard or slippery stops, not as a squeal in light braking.
• B (correct): Wear tabs are designed to squeal against the rotor when the pad material is nearly used up.
• C: A slipping drive belt squeals with engine speed or accessory load, not specifically when the brakes are applied.
• D: Tire pressure does not make a squeal from the brake area each time the brakes are applied.

Answer: A

Correct answer: Record when it happens and leave the codes stored. Intermittent faults are hard to find once they go away, so the evidence must be preserved. Write down the temperature, drive length and conditions, and keep the stored codes and freeze-frame data intact; clearing codes or disconnecting the battery would erase exactly what the technician needs.

• A (correct): Notes on conditions, together with stored codes and freeze-frame data, let the technician reproduce an intermittent fault.
• B: Removing power erases codes, freeze-frame data and monitor status, which are the evidence the shop needs.
• C: Stalling has many possible causes, and replacing a part without evidence often wastes money.
• D: Clearing removes the freeze-frame snapshot and resets monitors, and the cause will remain whether or not the lamp returns.

Answer: D

Correct answer: Read the codes and engine data before replacing parts. Stumbling or hesitation when the accelerator is pressed points to fuel delivery, ignition or air metering. With the wheels ruled out, reading the stored codes, freeze-frame and live engine data is the least intrusive way to narrow the cause before any part is replaced.

• A: Plugs are only one possibility; replacing them before reviewing data skips the evidence.
• B: The problem follows throttle input, not road speed, so the wheels are an unlikely source.
• C: Clearing the code erases freeze-frame data while doing nothing to locate the fault.
• D (correct): Hesitation under acceleration involves fuel, ignition or air metering, and codes and live data narrow which one.

Answer: B

Correct answer: 7 A. Use

• A: This multiplies power by voltage; current is power divided by voltage.
• B (correct): Current equals power divided by voltage: 84 W divided by 12 V is 7 A.
• C: This divides voltage by power, which inverts the formula.
• D: This subtracts the voltage from the power, which does not give current.

Answer: A

Correct answer: Shut down as the manual directs and let it cool before opening anything. Overheating with steam is a reason to stop. Park safely, shut down as the owner's manual directs, keep clear of the fan and belts, and never open a hot pressure cap; checks such as coolant level wait until the engine has cooled.

• A (correct): Waiting for the system to cool avoids scalding coolant and keeps hands away from fans that can start on their own.
• B: Opening a hot pressure cap can spray scalding coolant onto the driver.
• C: Sudden cold water on a hot engine can cause damage and puts the driver near steam and hot parts.
• D: Electric fans can start without warning, even with the key off, so hands must stay clear.