ASE Automobile (A1–A8) — All Questions

Electronic stability control (ESC) and traction control generally operate by using:

• a.The air conditioning compressor
• b.The evaporator core temperature sensor in the HVAC case
• c.The ABS wheel-speed sensors and hydraulic modulator✓
• d.The alternator diodes

ESC and traction control build on ABS hardware, using wheel-speed and yaw data to apply individual brakes and cut engine torque to keep the vehicle stable. A shared sensor fault can disable all three systems. They enhance, not replace, the base brakes.

Steel brake lines are joined and sealed using a:

• a.Soldered lap joint
• b.Double flare or ISO flare rated for high pressure✓
• c.Compression sleeve and nut like a water supply line
• d.Rubber grommet pushed into the fitting

Brake lines must use a double (or ISO) flare designed to hold high hydraulic pressure safely; ordinary compression fittings are not approved for brake lines. A single flare can crack and leak. The correct flare and fittings ensure a reliable seal.

Before installing a new or rebuilt master cylinder, the technician should:

• a.Pack the bore and pistons with wheel bearing grease
• b.Place it in a freezer overnight
• c.Fill the reservoir with power steering fluid
• d.Bench bleed it to remove the trapped air✓

Bench bleeding purges air from the master cylinder on the bench so the brakes can be bled properly after installation. Skipping this step traps air and gives a low, spongy pedal. Only the specified brake fluid is used.

A deteriorated flexible brake hose with an internal flap can act like a one-way valve, causing:

• a.One brake to drag because pressure cannot fully release✓
• b.An evaporative emission leak code from the fuel vapor canister
• c.Both rear brakes to lock together during any moderate stop
• d.A charging system fault that illuminates the battery warning lamp

When a hose breaks down internally, a flap can let pressure through but block its return, so that caliper stays partly applied and drags. The wheel overheats and pulls. Replacing the hose restores normal release.

A pulsation felt in the brake pedal that occurs mainly with rear drum brakes is most often caused by:

• a.Air trapped in the master cylinder
• b.An out-of-round brake drum✓
• c.A dirty cabin air filter restricting HVAC airflow
• d.A worn oxygen sensor

An out-of-round drum changes the shoe-to-drum contact as it rotates, producing a pulsation. Measuring the drum diameter at several points reveals it. Machining within limits or replacing the drum corrects it.

When bleeding brakes, keeping the master cylinder reservoir topped off matters because:

• a.Running it dry lets air back into the system✓
• b.It keeps the battery charged
• c.It adjusts the parking brake cable automatically
• d.It cools the engine by circulating brake fluid to the radiator

If the reservoir empties during bleeding, the master cylinder draws in air and you have to start over. Maintaining the level keeps the process moving forward. Using fresh, correct-spec fluid also matters.

Approved caliper grease is applied to the caliper slide pins to:

• a.Let the caliper move freely and prevent binding✓
• b.Seal the hydraulic circuit against leaks at the piston bore
• c.Provide extra friction between the pad and the rotor surface
• d.Raise the brake fluid's boiling point

Proper lubricant on the slide pins lets the caliper float and clamp evenly, preventing drag and uneven pad wear. The grease must be compatible with the rubber boots. Never put lubricant on the friction surfaces.

A vehicle pulls to one side during braking. All of the following can cause this EXCEPT:

• a.A restricted brake hose on one side limiting release at that wheel
• b.Contaminated linings on one wheel that grab or slip unevenly
• c.A seized caliper on one side that keeps its pads partly applied
• d.A pad set worn evenly the same amount on both front wheels✓

A brake pull comes from unequal braking side to side, such as a seized caliper, a restricted hose, or contaminated linings; pads worn evenly on both sides brake equally and do not pull. Diagnosis compares the two sides. Correcting the uneven condition centers the braking.

Brake linings that have become glazed (hard and shiny) from overheating will typically cause:

• a.A slow coolant leak from the engine's cooling system passages
• b.Reduced braking and noise until the linings are renewed✓
• c.A spongy, low pedal caused by air in the hydraulic brake lines
• d.An overcharged battery from extra load on the charging system

Glazing hardens the friction surface so it grips less and may squeal, lowering braking performance. Light glazing can sometimes be sanded, but badly glazed linings are replaced. Correcting the cause of overheating, such as a dragging caliper, prevents recurrence.

When the ABS warning lamp is on but the red brake lamp is off, the vehicle usually has:

• a.A parking brake that has locked and will not release
• b.No braking capability at all
• c.A boiling master cylinder overflowing from the reservoir
• d.Normal base braking with anti-lock disabled✓

An ABS-only fault disables anti-lock control but leaves conventional hydraulic braking working, so the pedal still stops the vehicle. The red lamp would indicate a base hydraulic problem instead. The ABS fault is diagnosed with a scan tool.

A banjo bolt connecting a brake hose to a caliper should be reassembled with:

• a.No sealing washers at all
• b.New copper crush washers, torqued to spec✓
• c.A coat of anti-seize applied to both washer sealing faces
• d.The original washers reused with thread sealant

Banjo fittings seal with soft copper crush washers that deform once, so new washers and proper torque are needed to prevent a leak. Reused washers often weep fluid. The banjo bolt has hollow passages for fluid flow.

The dry boiling point of a brake fluid is higher than its wet boiling point because:

• a.Absorbed moisture over time lowers the boiling point✓
• b.Pressure inside the sealed brake system has no effect
• c.The fluid gains additives as it ages
• d.Cold weather raises the boiling point

Glycol brake fluid absorbs moisture in service, and that water lowers the boiling point, which is why the wet rating is lower than the fresh dry rating. Boiled fluid produces vapor and a spongy pedal. Periodic fluid replacement restores the margin.

Brake rotor thickness variation (parallelism) differs from lateral runout in that thickness variation is measured with a:

• a.Vacuum gauge
• b.Micrometer at several points around the rotor✓
• c.Feeler gauge slipped between the pad and rotor at each wheel
• d.Dial indicator against the face of the spinning rotor

Thickness variation is the difference in rotor thickness measured with a micrometer at points around the disc, while runout is side-to-side wobble read with a dial indicator. Both cause pedal pulsation but are checked differently. Excess of either is corrected by machining or replacement.

A low brake pedal after a drum brake service, with no leaks or air, most often means the:

• a.Shoes need adjustment to reduce excess clearance✓
• b.Rotors machined thicker than the original specification
• c.Booster vacuum is higher than the engine can make
• d.Master cylinder bore is too large

Freshly installed shoes with too much clearance require several pedal strokes or manual adjustment to take up, causing a low pedal until adjusted. The self-adjusters or a manual adjustment set the clearance. A properly adjusted drum brake gives a high pedal.

A firm pedal that requires very high effort, with the engine running, most likely indicates a problem with the:

• a.Parking brake cable that has gone out of adjustment
• b.Wheel-speed sensor
• c.Vacuum booster or its vacuum supply✓
• d.ABS tone ring

A failed booster, leaking check valve, or lost vacuum supply removes the assist, leaving a hard, high-effort pedal even though the hydraulics are fine. Checking vacuum at the booster and the check valve isolates it. The brakes still work but require much more force.

The residual pressure (check) valve sometimes used in drum brake circuits is designed to:

• a.Raise rear brake pressure only during an anti-lock braking event
• b.Store extra brake fluid to also supply the hydraulic clutch system
• c.Block the parking brake from applying while the vehicle is moving
• d.Keep slight line pressure so wheel cylinder cups stay seated✓

A small residual pressure keeps the wheel cylinder cup lips seated so air is not drawn in and response stays quick. It is used on drum circuits, not on disc circuits, which need full release. The proportioning or metering functions are separate.

Grease or brake fluid contamination on one set of brake linings typically causes:

• a.A charging system fault lighting the battery lamp
• b.A pull or grab toward that wheel✓
• c.A perfectly balanced, straight stop
• d.A slow coolant leak

Contaminated friction material changes that wheel's braking, causing the vehicle to grab or pull to one side. The source of contamination, such as a leaking seal or caliper, must be fixed and the linings replaced. Cleaning alone rarely restores the friction material.

During pressure or gravity brake bleeding, the goal is to:

• a.Purge air from the lines so the pedal is firm✓
• b.Adjust the wheel bearing preload
• c.Raise the boiling point of the fluid in the system
• d.Add air to soften the pedal

All bleeding methods remove compressible air so the pedal becomes firm and braking is consistent. Pressure, vacuum, gravity, and manual methods all achieve this. Some ABS units require a scan tool to cycle the modulator during bleeding.

Technician A says a seized caliper can cause a pull and a burning smell from overheating. Technician B says it can boil the brake fluid and cause a fade. Who is correct?

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

A stuck caliper drags, overheating that wheel, which causes a pull, odor, and can boil the fluid into vapor. Both technicians are correct. The caliper, slides, and hose are inspected to find the cause.

Technician A says ignored worn brake pads can score the rotor. Technician B says continued metal-to-metal braking reduces stopping power. Who is correct?

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

When the friction material is gone, the metal backing grooves the rotor and braking suffers. Both technicians are correct. Timely pad replacement avoids rotor damage and a longer stop.

Steering axis inclination (SAI) is the:

• a.Difference in the toe setting between the left and right wheels
• b.Inward or outward tilt of the tire tread
• c.Forward or rearward tilt of the steering axis, seen from the side
• d.Inward tilt of the steering axis, viewed from the front✓

SAI is the inward tilt of the line through the steering pivots, viewed from the front, and it aids steering return and reduces required effort. It is built into the design and not directly adjustable. A bent part changes SAI and the included angle.

Setback in a wheel alignment refers to:

• a.The rear axle assembly being shifted ahead of the vehicle center
• b.The inward or outward tilt of the wheel measured from true vertical
• c.One front wheel sitting rearward of the other front wheel✓
• d.The measured distance between the two front tie rod adjusting sleeves

Setback describes one wheel sitting farther back than the opposite wheel, often from a collision or worn part. It can cause a pull or steering problems. It is compared side to side during a four-wheel alignment.

A vehicle that tracks slightly sideways (dog-tracks) usually has an incorrect:

• a.Front wheel camber angle set too far positive on both sides
• b.Thrust angle from rear axle position or rear toe✓
• c.Brake fluid level
• d.Battery voltage at full steering lock

The thrust angle is the direction the rear axle points; when it is off, the rear steers the vehicle at an angle and the steering wheel sits crooked. A four-wheel alignment corrects rear toe to center the thrust line. Bent parts or a shifted axle cause it.

In a MacPherson strut front suspension, the strut assembly serves as a damper and also as:

• a.The lower control arm
• b.The stabilizer bar
• c.An upper suspension locating member for the knuckle✓
• d.The steering gear that converts wheel input into road-wheel movement

The MacPherson strut combines the shock absorber with a structural role, locating the top of the knuckle so a separate upper control arm is not needed. This saves space and weight. The upper strut mount often includes a bearing for steering.

A binding or clunk felt through the steering when turning, traced to the top of a strut, often means a worn:

• a.Wheel-speed sensor
• b.Tie rod boot
• c.Upper strut mount or its bearing✓
• d.Brake caliper slide pin seized in its bracket

The strut mount bearing lets the strut rotate with the steering; when it wears, turning produces a bind, clunk, or memory steer. Replacing the mount and bearing restores smooth steering. It is inspected during strut service.

A broken coil spring will most commonly cause:

• a.A high, hard brake pedal that requires extra effort to fully stop
• b.An evaporative emission leak code from the fuel vapor canister
• c.A charging system fault that turns on the battery warning lamp
• d.A sagging corner, noise over bumps, and possible tire contact✓

A broken coil lowers ride height at that corner and can rattle or let the tire rub, upsetting alignment and handling. The spring must be replaced, often in pairs for balance. Corrosion is a common cause of spring breakage.

Worn control arm bushings can cause:

• a.A stuck-closed thermostat
• b.Higher engine oil pressure at idle and at cruise
• c.Clunks, alignment changes, and tire wear✓
• d.An overcharged battery

Deteriorated bushings let the control arm shift, producing noise, altering caster and camber, and wearing tires. They are inspected for cracking and looseness. Replacement restores correct geometry and quiet operation.

In a parallelogram (recirculating-ball) steering linkage, the idler arm functions to:

• a.Support and pivot the outer end of the center link✓
• b.Generate the hydraulic pressure for steering assist
• c.Adjust vehicle ride height with load
• d.Sense wheel speed for the ABS controller

The idler arm mirrors the pitman arm to keep the center link level and support the linkage on the passenger side. A worn idler arm causes play, wander, and tire wear. It is checked for vertical movement during inspection.

A recirculating-ball steering gear with excessive play on-center may be corrected by:

• a.Adjusting the sector (lash) screw to spec, if not worn out✓
• b.Adding brake fluid directly into the steering gear housing reservoir
• c.Replacing the wheel-speed sensors mounted at each front wheel
• d.Raising the tire pressure well above the placard specification

The sector adjustment removes excess lash in the gear's center position, restoring a tighter feel if the gear is not internally worn. Over-tightening causes binding. A badly worn gearbox is replaced instead.

A torn rack-and-pinion bellows (boot) should be replaced promptly because it:

• a.Sets an evaporative emission leak code from the fuel vapor canister
• b.Reduces the engine's oil pressure delivered to the crankshaft bearings
• c.Overcharges the battery by increasing load on the charging system
• d.Lets dirt and moisture into the rack, causing wear or leaks✓

The bellows keeps contaminants out of the inner tie rod and rack; once torn, grit and water enter and cause wear or a fluid leak. Replacing the boot early protects the rack. A neglected boot leads to costly rack replacement.

A power steering pump whine loudest at full lock, with a low fluid level, most likely means:

• a.A failed oxygen sensor that has slowed its response in the exhaust
• b.A clogged engine fuel filter restricting flow to the injectors
• c.A worn brake rotor causing a pulsation felt through the pedal
• d.Air in the system or low fluid, which is corrected first✓

Low fluid or aeration makes the pump whine, especially under the high load of full lock. Topping off the correct fluid and bleeding out the air often quiets it. A persistent noise after that may mean a worn pump.

On a vehicle with electric power steering (EPS), a loss of assist with a warning light usually means:

• a.The brake hydraulic system has air trapped in one of its circuits
• b.The air conditioning system has been overcharged with refrigerant
• c.The EPS system set a fault and disabled assist, leaving manual steering✓
• d.The engine is completely out of oil and has lost oil pressure

An EPS fault disables the motor assist but the steering remains mechanically connected, so the wheel gets heavy and a light comes on. The system is diagnosed with a scan tool for codes. Common causes include the torque sensor, motor, or a voltage problem.

Excessive free play felt at the steering wheel before the wheels respond can be caused by:

• a.An overcharged air conditioning system raising the high-side pressure
• b.Worn tie rod ends, idler arm, or a loose steering gear✓
• c.A weak battery unable to hold a charge between vehicle uses
• d.A dirty cabin air filter restricting airflow through the HVAC case

Play in the linkage or gear shows up as steering-wheel free travel before the wheels turn, causing wander and imprecise steering. Each joint is checked for looseness. Worn parts are replaced before an alignment.

A wheel bearing drone that changes as the vehicle is gently swayed side to side is diagnosed as:

• a.A worn wheel bearing on the loaded side✓
• b.A worn oxygen sensor
• c.A leaking heater core
• d.A slipping clutch disc that cannot hold torque in high gear

A failing wheel bearing drones and the noise changes as cornering loads shift onto or off of it, helping identify which side. A road test with gentle sway maneuvers isolates it. Play or roughness is confirmed with the wheel raised.

On a serviceable tapered wheel bearing, correct preload is set by:

• a.Leaving the spindle nut only finger tight and installing the cotter pin
• b.Tightening the spindle nut as tight as an impact gun can drive it
• c.Seating the bearing, then backing off and adjusting per spec✓
• d.Using a lock washer alone with no specified torque on the nut

Adjustable tapered bearings are seated, then set to a slight preload or endplay following the procedure so they neither bind nor run loose. Too tight causes overheating; too loose causes play and wander. A cotter pin or lock secures the final setting.

Many modern sealed hub assemblies contain the wheel bearing and also:

• a.The brake master cylinder that supplies that corner
• b.An integrated wheel-speed sensor for the ABS✓
• c.A fuel pressure regulator
• d.The alternator

Sealed hub units combine the bearing, flange, and often the ABS speed sensor or tone ring in one non-serviceable assembly. A bad hub bearing can also set an ABS code if the integrated sensor is affected. The unit is replaced rather than repacked.

After certain tire or wheel services, a tire pressure monitoring system (TPMS) may require a:

• a.Full brake bleed at all four wheels before the vehicle is driven
• b.Relearn so the module recognizes each sensor's position✓
• c.Coolant flush and refill to restore proper engine temperature
• d.Fuel system decarbonizing service to clear the intake passages

Rotating tires or replacing sensors can require a TPMS relearn so the module maps each sensor to its wheel position. Without it, the system may warn or show wrong locations. The procedure varies by manufacturer and tool.

A tire worn on one edge only, with the tread blocks otherwise even, most directly indicates a:

• a.Toe problem
• b.Camber problem at that wheel✓
• c.Wheel balance problem, which gives a speed-related vibration
• d.Brake problem causing a pull to that side

Wear concentrated on a single shoulder points to excessive positive or negative camber tilting the tire. Feathered wear across the tread instead indicates a toe error. Correcting the alignment angle stops the wear.

Directional tires marked with a rotation arrow should be rotated so that they:

• a.Stay on the same side, moving front to rear✓
• b.Are dismounted and remounted backward on the wheel
• c.Cross over to the opposite side at every rotation
• d.Are never rotated at all

Directional tires must keep their intended rotation direction, so they move front-to-rear on the same side rather than crossing sides. Mounting them backward hurts wet traction and noise. Always follow the correct pattern for the tire type.

A tire's DOT date code is important to check because tires:

• a.Change their physical size and diameter as they age
• b.Age and can deteriorate even with adequate tread✓
• c.Gain load capacity the longer they are used
• d.Require no age consideration as long as the tread is legal

Rubber ages and can crack or fail regardless of remaining tread, so the DOT week/year code helps judge whether an old tire should be replaced. Old spare tires are a common concern. Age plus condition guide replacement.

Dynamic wheel balancing differs from static balancing in that dynamic balancing corrects for:

• a.Only up-and-down imbalance in a single plane
• b.The tire's inflation pressure
• c.Both up-and-down and side-to-side imbalance✓
• d.The remaining tread depth

Dynamic (spin) balancing places weights to cancel imbalance in two planes, eliminating both hop and shimmy, while static balancing addresses only the vertical plane. Modern balancers do dynamic balancing. Correct balance prevents vibration and cupping.

Mixing a radial tire with a bias-ply tire on the same axle is not recommended because it can cause:

• a.A slow coolant leak from the engine's cooling system passages
• b.Unstable handling from different construction and grip✓
• c.A charging system fault that turns on the battery warning lamp
• d.An evaporative emission leak code from the fuel vapor canister

Radial and bias-ply tires flex and grip differently, so mixing them on an axle produces unpredictable handling. Matching tire type, size, and condition keeps the vehicle stable. Manufacturers specify consistent tires on each axle.

A change in vehicle ride height, such as from sagging springs, affects alignment because it:

• a.Affects only the brakes and leaves the steering angles unchanged
• b.Changes only the tire inflation pressure
• c.Has no measurable effect on alignment angles
• d.Alters camber and toe as the suspension geometry shifts✓

Ride height sets where the suspension sits in its travel, so a sagging spring changes camber and toe and can cause a pull or tire wear. Ride height is checked and corrected before setting alignment angles. Worn springs are replaced first.

Bump steer is a condition in which the:

• a.Brakes grab or release unevenly while driving on a rough road
• b.Tires slowly lose air pressure each time the vehicle hits a bump
• c.Steering wheel locks up whenever the brakes are firmly applied
• d.Wheels steer slightly on their own as the suspension moves✓

Bump steer occurs when suspension travel changes toe, so hitting a bump makes the vehicle dart. It often results from bent parts, wrong ride height, or mismatched tie-rod geometry. Correcting the geometry eliminates the darting.

A shock absorber found leaking oil should be:

• a.Overinflated with compressed air
• b.Refilled with fresh brake fluid and reinstalled
• c.Wiped clean of the leaking oil and reinstalled as it was
• d.Replaced, usually in pairs on the same axle✓

A shock leaking its oil has lost damping and should be replaced, and doing both on an axle keeps handling balanced. Worn shocks cause bounce, cupping, and poor control. A quick bounce test and visual leak check confirm the condition.

An air (load-leveling) suspension that will not hold ride height most likely has a:

• a.Leaking air spring, dead compressor, or leaking line✓
• b.Faulty oxygen sensor
• c.Worn brake pad set that has gone metal-to-metal at one wheel
• d.Clogged fuel injector

Air suspension holds height by adding air, so a leak in a spring, line, or valve, or a dead compressor lets the vehicle sag. The system is checked for leaks and compressor operation. A height sensor fault can also cause improper leveling.

A vehicle that drifts on a level road but tracks straight on a crowned road may be reacting to:

• a.A boiling master cylinder overflowing from the reservoir
• b.An overcharged battery
• c.Road crown rather than a true alignment fault✓
• d.A clogged EGR valve that has begun to affect the idle

Roads are crowned for drainage, which can make a properly aligned vehicle drift slightly toward the low side. Distinguishing crown drift from a true pull avoids unnecessary repairs. Swapping tires and checking cross-camber help confirm.

Radial runout of a tire and wheel assembly refers to:

• a.The toe setting of the front wheels
• b.Side-to-side wobble of the assembly across its face
• c.The inward or outward tilt of the tire
• d.Up-and-down (out-of-round) variation as it rotates✓

Radial runout is out-of-roundness that causes a vertical hop, while lateral runout is side-to-side wobble. Excess runout causes vibration that balancing alone will not fix. It is measured with a dial indicator against the tire or rim.

For a hub-centric wheel, the wheel is centered on the hub by the:

• a.Lug nuts alone as they are tightened in a crisscross pattern
• b.Tire bead sealing against the wheel lip
• c.Center bore fitting over the hub's machined pilot✓
• d.Valve stem seating against its hole in the rim of the wheel

A hub-centric wheel locates on the machined hub pilot at its center bore, so the load and centering are carried there while the lugs clamp it. Lug-centric wheels instead center on tapered lug seats. Correct centering prevents vibration.

A steering shimmy that appears at a specific highway speed and smooths above or below it is most often:

• a.A dirty cabin air filter
• b.A worn oxygen sensor
• c.A stuck-closed thermostat
• d.Wheel and tire imbalance✓

An imbalance excites a vibration at the speed where the heavy spot's frequency peaks, felt as a shimmy that comes and goes with speed. Balancing corrects it. Runout or a worn part can cause similar symptoms if balancing does not resolve it.