ASE Automobile (A1–A8) — All Questions

A hiss that changes with throttle, plus a rough idle and lean fuel trims, most likely indicates:

• a.A vacuum or intake manifold gasket leak adding unmetered air✓
• b.A worn crankshaft bearing that knocks louder as engine load rises
• c.A slipping serpentine belt squealing under accessory drive load
• d.A clogged oil filter forcing oil through the filter's bypass valve

Unmetered air entering through a leaking intake or vacuum line makes a hiss and leans the mixture, roughening idle and driving fuel trims positive. Smoke testing pinpoints the leak. Sealing the leak restores idle quality.

The purpose of the crankcase ventilation (PCV) system in managing airflow is to prevent:

• a.Pressure buildup and sludge from blow-by in the crankcase✓
• b.Engine coolant from being drawn into the oil through the galleries
• c.The catalytic converter from overheating during hard acceleration
• d.The alternator from overcharging the battery at higher rpm

By drawing blow-by vapors out of the crankcase, the PCV system relieves internal pressure and reduces moisture and sludge, sending the vapors to be burned. A blocked system builds pressure that pushes out oil at seals. It also lowers emissions.

After a coolant refill, an engine has intermittent overheating and inconsistent heater output. The MOST likely cause is:

• a.A cracked cylinder head letting combustion gases into the coolant
• b.A worn oil pump unable to maintain pressure at operating speed
• c.A seized brake caliper dragging and overheating one front wheel
• d.Trapped air (an airlock) that must be bled from the system✓

Air trapped after service blocks coolant flow, causing erratic temperature and poor heat until it is purged through the bleeder or by proper fill procedure. Many engines require a specific bleeding sequence. Confirming full coolant flow resolves it.

Technician A says a straightedge check can reveal a warped intake manifold sealing surface. Technician B says an intake gasket leak can cause coolant loss or a vacuum leak. Who is correct?

• a.Technician A only
• b.Neither A nor B
• c.Both A and B✓
• d.Technician B only

A straightedge reveals a warped intake flange, and depending on design an intake gasket can leak coolant, oil, or vacuum. Both technicians are correct. The failure mode depends on which passages the gasket seals on that engine.

Technician A says excessive valve guide clearance can cause oil consumption and smoke. Technician B says worn guides can cause erratic seating and a misfire. Who is correct?

• a.Technician B only
• b.Neither A nor B
• c.Both A and B✓
• d.Technician A only

Loose guides let oil down the stems and allow the valve to wander off its seat, causing oil burning and possible misfire. Both technicians are correct. Guide and seal service restores control of the valve and oil.

A shudder at light throttle around 40-50 mph that smooths out under harder acceleration most likely indicates:

• a.An unbalanced tire
• b.A worn outer CV joint that clicks in tight turns
• c.A torque converter clutch (lockup) shudder✓
• d.A slipping serpentine belt

TCC shudder appears when the converter clutch applies at cruise, often from worn friction material or degraded fluid, and it disappears when the clutch releases under heavier throttle. Fresh fluid of the correct type sometimes cures early shudder. Scan data confirms lockup timing.

In a modern electronically controlled automatic, shift points are determined mainly by the:

• a.Mechanical governor and vacuum modulator working on their own
• b.Throttle cable position acting alone
• c.A driver-adjustable vacuum valve
• d.Control module using sensor inputs and shift solenoids✓

Electronic automatics use the control module reading throttle, speed, and load to command shift solenoids, replacing the old governor and vacuum modulator. This allows adaptive, precise shifting. Faults set codes read with a scan tool.

The valve body in an automatic transmission functions to:

• a.Generate the engine's intake vacuum used by the accessory systems
• b.Direct hydraulic fluid to apply the correct clutches and bands✓
• c.Charge the battery through a gear-driven generator inside the case
• d.Cool the engine oil by passing it through internal fluid passages

The valve body is the hydraulic control center that routes pressurized fluid to the apply devices for each gear, guided by the solenoids and pump pressure. A stuck valve causes shift complaints. It works with the electronic controls to time shifts.

Planetary gearsets are used in automatic transmissions mainly because they can provide:

• a.Several gear ratios plus reverse in a compact, strong unit✓
• b.Electrical power generation to help run the vehicle's accessories
• c.Cooling for the engine by circulating fluid through the gearset
• d.Only one fixed ratio, which keeps the whole assembly very simple

By holding or driving different members, a planetary set delivers several forward ratios plus reverse in a compact package that stays in constant mesh. This makes automatic shifting smooth and durable. Clutches and bands control which members are held.

An automatic transmission will not move in any gear, forward or reverse. A likely cause is:

• a.A single worn synchronizer preventing engagement of just one gear
• b.A dragging brake caliper holding the vehicle back on one wheel
• c.A worn outer CV joint that has begun to click loudly during turns
• d.Very low fluid or a failed pump producing no line pressure✓

No movement in any range points to a loss of hydraulic pressure from low fluid or a failed pump, since pressure applies every gear. A pressure test confirms it. Synchronizers exist only in manual transmissions.

A manual transmission grinds only when shifting into one particular gear. The MOST likely cause is:

• a.A low engine oil level
• b.A worn front wheel bearing
• c.A slipping serpentine belt under accessory load
• d.A worn synchronizer for that specific gear✓

A synchronizer matches shaft speeds so the gear engages smoothly; when one wears, that specific gear grinds while others shift fine. Clutch drag can also cause grinding but usually affects all gears. Replacing the worn synchro corrects it.

The synchronizer in a manual transmission functions to:

• a.Generate line pressure that applies the clutches during each shift
• b.Match gear and shaft speeds for smooth, clash-free engagement✓
• c.Engage the starter motor with the flywheel ring gear when cranking
• d.Lubricate the clutch disc so it engages the flywheel more smoothly

The synchronizer brings the rotating gear and shaft to the same speed before the collar locks them, preventing clash. Worn synchros cause grinding in that gear. Double-clutching can help engage a transmission with weak synchros.

A manual-transmission clutch that chatters (shudders) as it engages is most often caused by:

• a.An oil-soaked disc or a worn or warped component✓
• b.A stuck-closed engine thermostat
• c.An overcharged air conditioning system raising high-side pressure
• d.Too much brake fluid in the clutch master cylinder

Chatter usually comes from a glazed or oil-soaked disc, a warped flywheel, or worn parts that grab unevenly during engagement. A leaking rear main or input seal can soak the disc. Correcting the leak and replacing the disc cures it.

A hydraulic clutch pedal that goes to the floor and will not disengage the clutch most likely has:

• a.A worn front wheel bearing that has developed play and roughness
• b.Low fluid or air in the clutch hydraulics, or a failed cylinder✓
• c.A warped brake rotor causing a pulsation through the brake pedal
• d.A clogged cabin air filter restricting airflow from the HVAC vents

Loss of hydraulic pressure from low fluid, air, or a leaking master or slave cylinder prevents the clutch from releasing, so the pedal feels dead. Bleeding and repairing the leak restores operation. The clutch hydraulic system is separate from the brakes but uses similar fluid.

A noise present only when the clutch pedal is depressed, stopping when released, most likely indicates a worn:

• a.Water pump bearing
• b.Release (throwout) bearing✓
• c.Pilot bearing, noisy with the transmission in gear
• d.Front wheel bearing, which drones with vehicle speed

The release bearing spins only while the pedal is down and pressing on the pressure plate fingers, so noise that appears then points to it. A pilot bearing, by contrast, is noisy with the pedal down and the transmission in gear. Replacing the release bearing with the clutch is standard practice.

A flywheel with heat cracks or a worn friction surface should be:

• a.Left as-is as long as a new clutch disc is installed
• b.Painted over the cracked area to seal the heat checks
• c.Coated with high-temperature grease
• d.Resurfaced or replaced during clutch service✓

A scored or heat-checked flywheel prevents proper clutch engagement and causes slipping or chatter, so it is machined or replaced when the clutch is done. Dual-mass flywheels are inspected for excessive play and usually replaced. A fresh surface ensures full disc contact.

A clunk heard shifting from Drive to Reverse or on throttle tip-in, with the transmission otherwise fine, often indicates:

• a.A clogged fuel filter
• b.A broken or worn engine or transmission mount✓
• c.A worn oxygen sensor
• d.A low brake fluid level in the master cylinder reservoir

A failed mount lets the powertrain shift on its supports, producing a clunk during gear and load changes. Inspecting the mounts for cracks and separation confirms it. Worn U-joints can cause a similar driveline clunk.

The transfer case in a four-wheel-drive vehicle is used to:

• a.Split engine power between the front and rear axles✓
• b.Filter the engine oil before it reaches the main bearings
• c.Increase A/C system pressure
• d.Charge the vehicle's battery

The transfer case distributes torque to both axles and often provides a low range for extra reduction. Low fluid or worn chains and clutches cause noise or engagement problems. It is serviced with the specified fluid.

A limited-slip differential that chatters or shudders while turning slowly is often corrected by:

• a.Increasing the tire pressure well above the placard specification
• b.Adding the specified friction-modifier additive to the gear oil✓
• c.Replacing the wheel speed sensor mounted at the affected axle
• d.Adding a small amount of brake fluid directly into the axle housing

Clutch-type limited-slip units need a friction modifier so the plates release smoothly; without it, they grab and chatter in tight turns. Using the correct gear oil with additive cures it. Persistent noise may mean worn clutch plates.

When setting up a ring-and-pinion gear, the tooth contact pattern is checked to verify correct:

• a.Pinion depth and backlash✓
• b.Tire balance and radial runout
• c.Brake fluid level
• d.Ignition timing advance at the crankshaft sensor

A marking-compound pattern on the ring gear teeth reveals whether pinion depth and backlash are correct before final assembly. An improper pattern causes whine and premature wear. Shims and adjusters are changed to center the pattern.

Gear oil leaking from an axle seal onto the brake can cause:

• a.A charging system fault
• b.Contaminated linings and a brake pull or grab✓
• c.An evaporative emission leak code from the vapor canister
• d.Higher engine oil pressure at idle

A leaking axle seal lets gear oil reach the brake shoes or pads, causing them to grab or the vehicle to pull. The seal must be replaced and the friction material cleaned or renewed. Ignoring it risks unsafe braking.

Many automatic transmissions route fluid through a cooler located in the:

• a.Air cleaner housing
• b.Fuel tank
• c.Radiator, sometimes with a separate auxiliary cooler✓
• d.Exhaust manifold, using engine heat to warm the fluid when cold

ATF is cooled in a heat exchanger inside the radiator, sometimes with an added external cooler for heavy use, because heat is the main enemy of the fluid. A failed internal cooler can cross-contaminate coolant and ATF. Adequate cooling extends transmission life.

An automatic that shifts fine when cold but slips as it warms up most likely has:

• a.A clogged cabin air filter reducing airflow through the HVAC case
• b.A worn outer tie rod end introducing play into the steering
• c.A misadjusted parking brake dragging the rear brakes when warm
• d.Worn clutches or low pressure that worsen as fluid thins✓

As fluid warms and thins, marginal clutches or seals slip more, so a transmission that fails only when hot points to internal wear or low pressure. A pressure test at temperature helps confirm. Correct fluid level and condition are checked first.

A momentary rise in engine rpm during an upshift, with no matching increase in vehicle speed, is called:

• a.Engine braking
• b.Shift flare (slippage during the shift)✓
• c.Converter lockup
• d.Torque multiplication in the converter during acceleration

Flare happens when the oncoming clutch or band applies too slowly and engine speed briefly runs up during the shift, indicating wear or low pressure. It stresses the friction elements. Diagnosis includes fluid condition, pressure, and solenoid operation.

A code for the torque converter clutch circuit (such as P0741) most often relates to:

• a.A worn front wheel bearing
• b.The TCC failing to lock up or slipping too much✓
• c.A leaking radiator cap
• d.A faulty ABS wheel-speed sensor at one of the wheels

This code sets when the module sees the converter clutch not achieving or holding lockup, from a stuck solenoid, worn clutch, or fluid issues. Persistent slip overheats the fluid. Checking the solenoid, fluid, and valve body is the next step.

A manual transmission that pops out of gear on its own most commonly indicates:

• a.Worn shift detents, synchronizers, or a broken mount✓
• b.A clogged fuel injector
• c.A weak battery
• d.An overcharged air conditioning system raising high-side pressure

Worn detent springs, damaged synchro teeth, or excessive powertrain movement from a bad mount let the gear disengage under load. Inspection of the linkage, internal parts, and mounts finds the cause. Continued use accelerates wear.

The correct way to remove air from a hydraulic clutch system is to:

• a.Bleed at the slave cylinder while keeping the reservoir full✓
• b.Pump the pedal until it firms up and then simply drive the vehicle
• c.Loosen the transmission mount to let the trapped air work its way out
• d.Add a heavier, thicker fluid so the trapped air cannot compress

Air makes the clutch hydraulic pedal soft and prevents full release, so the system is bled at the slave bleeder like a brake circuit while topping the reservoir. A gravity or pressure bleed removes trapped air. Then full disengagement returns.

A torn CV joint boot found during inspection should be addressed promptly because:

• a.It causes the alternator to overcharge and boil the battery dry
• b.It reduces engine oil pressure delivered to the crankshaft bearings
• c.It sets an evaporative emission leak code from the vapor canister
• d.Lost grease and entering dirt will quickly ruin the joint✓

Once the boot tears, grease flings out and grit gets in, wearing the joint until it clicks and fails. Replacing the boot early, before contamination, can save the joint. A neglected joint requires a full axle replacement.

A vehicle will not crank in Park but cranks in Neutral. The MOST likely cause is:

• a.A slipping torque converter
• b.A leaking axle seal
• c.A worn clutch disc slipping under load in the higher gears
• d.A faulty transmission range (neutral safety) switch✓

The range switch tells the starter circuit the vehicle is in Park or Neutral; when it is misadjusted or failing, starting may work in only one position. Adjusting or replacing the switch restores normal cranking. It also feeds gear position to the module.

A transmission fluid cooler line that leaks lowers the fluid level, which can lead to:

• a.Improved shift quality because the clutches apply quicker
• b.A stronger clutch engagement
• c.Higher fuel economy from reduced drag in the transmission
• d.Slipping, overheating, and internal damage✓

Low fluid from a leaking cooler line reduces pressure and cooling, causing slip and heat that damage the clutches. The line is repaired and the fluid refilled to the correct level. Prompt repair prevents costly failure.

An automatic transmission used for frequent trailer towing benefits most from:

• a.A higher-octane fuel to lower operating temperature
• b.An auxiliary cooler to control fluid temperature✓
• c.A larger battery
• d.A thicker grade of engine oil

Towing loads the transmission and raises fluid temperature, so an auxiliary cooler keeps the ATF within a safe range and extends its life. Heat is the leading cause of transmission failure. Fluid condition should also be monitored under heavy use.

The vehicle speed sensor (VSS) signal is used by the transmission controller to:

• a.Control the air conditioning compressor clutch air gap
• b.Measure oxygen content in the exhaust
• c.Help determine shift timing and converter lockup✓
• d.Read the coolant level in the radiator and overflow reservoir

The controller compares vehicle speed with throttle and load to schedule shifts and apply the converter clutch. A faulty VSS can cause erratic or no shifts and a speedometer fault. Its signal is verified with a scan tool.

In a continuously variable transmission (CVT), the ratio is changed by:

• a.Shifting between fixed planetary gearsets held by clutches and bands
• b.Varying the effective diameter of two belt-linked pulleys✓
• c.Engaging a series of dog clutches to select individual gear pairs
• d.Changing the final drive ring-and-pinion gear ratio on the fly

A CVT uses a steel belt or chain running between variable-width pulleys, so moving the pulley halves changes the ratio smoothly with no fixed steps. This keeps the engine near its most efficient speed. CVT fluid is a specific type not interchangeable with ATF.

Technician A says worn universal joints can cause a driveline clunk and vibration. Technician B says a bent or unbalanced driveshaft can cause a speed-related vibration. Who is correct?

• a.Both A and B✓
• b.Technician B only
• c.Neither A nor B
• d.Technician A only

Worn U-joints clunk and vibrate, and a bent or unbalanced shaft vibrates more as speed rises. Both technicians are correct. Inspecting the joints, runout, and balance isolates the source.

Technician A says overheated automatic transmission fluid turns dark and smells burnt. Technician B says burnt fluid indicates the friction material may be damaged. Who is correct?

• a.Neither A nor B
• b.Technician A only
• c.Technician B only
• d.Both A and B✓

Overheating darkens the fluid and produces a burnt odor, and that heat comes from slipping friction elements that are wearing. Both technicians are correct. Fluid condition is an important early diagnostic clue.

The hydraulic brake system transmits force to all wheels based on the principle that:

• a.Liquids expand in volume when they are put under high pressure
• b.Fluid pressure gradually decreases as it travels farther from the pedal
• c.Pressure on a confined fluid is transmitted equally throughout✓
• d.Fluid compresses under pressure and stores energy to release later

Pascal's principle states that pressure in a confined, incompressible fluid is transmitted undiminished throughout, which is why pedal force reaches every wheel. Air in the system defeats this because air compresses. This is the basis of hydraulic braking.

A modern tandem (dual) master cylinder is designed so that:

• a.Both circuits fail together when one leaks
• b.A leak in one circuit still leaves the other working✓
• c.It boosts pedal effort by itself without vacuum or hydraulic assist
• d.It also stores and supplies fluid for the clutch system

The tandem master cylinder splits braking into two independent hydraulic circuits so that a single leak leaves partial braking rather than total loss. The pedal travels farther and the warning light comes on. This redundancy is a required safety feature.

The red brake warning light (not the ABS lamp) can be triggered by:

• a.Low fluid or a pressure difference between the two circuits✓
• b.A dirty cabin air filter that has restricted airflow from the vents
• c.A high engine coolant temperature approaching the overheat point
• d.A worn wheel-speed sensor sending an erratic signal to the module

The base brake warning lamp responds to low reservoir fluid, an applied parking brake, or a pressure imbalance sensed by the differential switch. It signals a hydraulic problem needing attention. The separate amber ABS lamp covers anti-lock faults.

Drum brakes use a self-adjuster mechanism that typically operates when the:

• a.Vehicle is parked on a steep hill
• b.Wheels are removed from the vehicle during a tire rotation
• c.Ignition switch is first turned on
• d.Brakes are applied while the vehicle is backing up✓

Many drum self-adjusters take up shoe clearance during reverse stops, turning the star wheel a little at a time. If the mechanism seizes, the pedal gets low as the shoes wear. Proper adjustment restores a high, firm pedal.

A wheel cylinder leaking brake fluid onto the drum brake shoes will cause:

• a.An increase in fuel economy from lower rolling resistance there
• b.An overcharged battery
• c.Contaminated linings and reduced or grabby braking there✓
• d.A high, firm pedal needing very little effort

A leaking wheel cylinder soaks the shoes with fluid, ruining the friction material and causing grab or reduced braking. Both the cylinder and shoes must be replaced. Fluid on the drum also signals the leak.

Brake fade after repeated hard stops, where the pedal stays firm but braking weakens, is most often:

• a.A cracked windshield
• b.Mechanical fade from overheated linings losing friction✓
• c.A worn front wheel bearing
• d.Air being drawn into the master cylinder past its worn seal

When linings overheat they temporarily lose their friction coefficient, so the pedal feels normal but stopping power drops. Fluid fade, by contrast, gives a soft pedal from boiling fluid. Cooling and quality linings reduce mechanical fade.

After machining a brake rotor on a lathe, the technician should apply a:

• a.Bead of RTV silicone around the rotor edge to reduce vibration
• b.Non-directional finish and clean it before installing pads✓
• c.Layer of thread sealant to the rotor hat where it meets the hub
• d.Thin coat of high-temperature grease across the rotor friction surface

A non-directional finish helps the new pads seat and prevents pad noise or pull, and the surface is cleaned of metal dust before assembly. Directional swirl marks can act like a screw thread. Proper prep improves braking and reduces comebacks.

Excessive lateral runout of a brake rotor is measured with a:

• a.Test light at the wheel-speed sensor connector
• b.Vacuum gauge
• c.Feeler gauge inserted between the pad and the rotor surface
• d.Dial indicator reading against the rotor face✓

A dial indicator mounted to read the spinning rotor face shows lateral runout, which over time creates thickness variation and pedal pulsation. Excess runout may come from the rotor, hub, or debris behind the rotor. It is corrected by machining, indexing, or replacement.

A seized caliper slide pin will most likely cause:

• a.Uneven (tapered) pad wear and a possible pull✓
• b.An evaporative emission leak code from the vapor canister
• c.A charging system fault
• d.A boiling radiator and rapid coolant loss from the overflow

When a slide pin sticks, the caliper cannot center over the rotor, so one pad wears faster and the vehicle may pull. Cleaning, lubricating, or replacing the pins and boots restores even movement. Neglected pins also cause drag and heat.

Compared with semi-metallic pads, ceramic brake pads are generally chosen for:

• a.Lower noise and less visible brake dust✓
• b.Higher rotor wear in all conditions
• c.A lower purchase cost as their only advantage
• d.The greatest heat capacity for racing use

Ceramic pads typically run quieter and produce lighter-colored, less-visible dust, which suits many passenger vehicles. Semi-metallic pads handle high heat well but can be noisier and dustier. Pad choice balances noise, dust, and heat needs.

A constant high-pitched squeal that stops when the brakes are applied usually indicates:

• a.The pad wear indicator dragging on the rotor✓
• b.Air trapped in the master cylinder past a worn piston seal
• c.A worn front wheel bearing
• d.A leaking wheel cylinder soaking the rear shoes

The mechanical wear indicator drags on the rotor when the pads are thin, squealing until the brakes are pressed. It is a warning to replace the pads soon. Ignoring it leads to metal-to-metal grinding and rotor damage.

The check valve in a vacuum brake booster is designed to:

• a.Bleed atmospheric air into the booster
• b.Adjust the parking brake cable tension as the pads wear
• c.Hold vacuum in the booster so a reserve is available✓
• d.Regulate hydraulic brake fluid pressure sent to the calipers

The one-way check valve traps engine vacuum in the booster so the driver gets assisted stops even after the engine stops or during low-vacuum conditions. A faulty valve gives a hard pedal or loss of reserve. It is a simple but important part.

A hydro-boost power brake system gets its assist from:

• a.The power steering pump's hydraulic pressure✓
• b.Exhaust backpressure stored to apply the brakes
• c.The alternator's output routed to a motor on the booster
• d.Engine intake manifold vacuum

Hydro-boost uses pressurized power steering fluid instead of vacuum to provide brake assist, common on diesels and heavy vehicles with little manifold vacuum. A steering or belt problem can affect braking assist. It stores a small hydraulic reserve for stops after shutdown.

The ABS hydraulic control unit prevents lockup by:

• a.Applying the parking brake automatically during hard braking
• b.Adding intake vacuum to each wheel circuit
• c.Increasing the master cylinder bore size
• d.Cycling solenoid valves to modulate pressure at a wheel✓

The modulator's solenoid valves cycle to hold, release, and reapply pressure at a wheel that is about to lock, based on wheel-speed data. This keeps the wheels rolling for steering control. The pump restores pressure during release cycles.

A damaged or contaminated tone ring (reluctor) at one wheel will most likely cause:

• a.A parking brake that will not hold the vehicle on a moderate grade
• b.A boiling master cylinder that overflows the brake fluid reservoir
• c.An erratic wheel-speed signal and false ABS activation or a code✓
• d.A soft, spongy brake pedal from air trapped in the hydraulic system

A cracked, rusty, or debris-covered tone ring produces an irregular signal, which the ABS module may read as a wheel about to lock, causing false activation or a code. Inspecting and cleaning or replacing the ring corrects it. The sensor air gap is also checked.