Free ASE A5 Exam Flashcards

Pressure applied to a confined brake fluid is transmitted throughout the fluid. A master-cylinder piston creates line pressure that acts on caliper or wheel-cylinder piston area to produce braking force.

A tandem master cylinder supplies two hydraulic circuits so one circuit failure does not necessarily eliminate all service braking. Pedal travel and stopping ability can change substantially after a circuit failure.

At brake release, the compensating port connects the pressure chamber to the reservoir. It lets expanding fluid return to the reservoir; a blocked port can trap pressure and cause brake drag.

A pedal that continues to sink under steady force while fluid level stays stable can indicate internal master-cylinder bypass. Confirm the concern with the manufacturer's diagnostic procedure before replacing parts.

Bench bleeding removes trapped air from the master-cylinder bore before installation. Follow the component maker's procedure and use the specified brake fluid so air is not carried into the rest of the hydraulic system.

Use only the fluid specification called for by the vehicle manufacturer. Keep containers sealed and avoid contamination; incompatible or contaminated fluid can damage components and degrade brake performance.

Inspect rigid lines and fittings for leaks, corrosion, dents, kinks, and support problems. Inspect flexible hoses for leakage, cracking, bulging, wear, kinks, and correct routing through suspension travel.

A damaged hose can restrict fluid return and leave a brake applied after pedal release. Compare symptoms and pressures using approved procedures; do not loosen fittings around hot components without proper safety precautions.

A proportioning valve limits rear brake pressure as braking demand rises to help maintain stable front-to-rear braking. Its operation and test method depend on the system design and manufacturer specifications.

On systems that use one, a metering valve delays front disc-brake pressure briefly so rear drum shoes can overcome return-spring tension. Do not assume every vehicle uses the same valve arrangement.

A pressure differential device can detect a significant pressure difference between hydraulic circuits and trigger a brake warning indication. It identifies a system imbalance, not the exact failed component.

Use the vehicle manufacturer's bleeding sequence and method. ABS-equipped systems may require scan-tool functions or other specified steps; a generic sequence can leave air trapped or produce an incorrect diagnosis.

With the engine off, deplete stored assist by applying the pedal as directed by the manufacturer. Holding pedal force while starting the engine should show a change consistent with power assist if the system is operating properly.

The check valve helps retain vacuum in the booster when engine vacuum falls. Test its direction of flow and sealing according to manufacturer instructions; a failed valve can reduce reserve assist.

A hydro-boost unit uses hydraulic pressure from a power-steering or dedicated hydraulic source instead of engine vacuum. Service, refill, and bleed it using the vehicle manufacturer's procedure.

Free travel is the initial pedal movement before brake application. Too much or too little can signal adjustment, linkage, or hydraulic concerns; measure and adjust only to the manufacturer specification.

Inspect parking-brake cables, levers, equalizers, and related hardware for wear, corrosion, binding, and correct return. A cable adjusted too tightly can keep brakes partially applied.

Many electronic parking-brake systems require a manufacturer-specified service or maintenance mode before pad or caliper work. Forcing an actuator without the correct procedure can cause damage or faults.

Some rear disc calipers incorporate the parking-brake mechanism. Retract and adjust the piston only with the approved method, then verify the lever or actuator returns fully when the parking brake is released.

A brake warning lamp can relate to hydraulic imbalance, parking-brake status, fluid level, or another circuit depending on vehicle design. Verify the concern, inspect basics, and follow the wiring diagram and diagnostic routine.

Verify the customer concern and review applicable service information before replacing parts. Then inspect for safety-critical faults and use measured test results to identify the cause rather than diagnosing by symptom alone.

In a conventional drum brake, shoe action depends on drum rotation and the anchor arrangement. Use vehicle-specific service information because drum layouts and hardware differ across designs.

A wheel cylinder converts hydraulic pressure into outward movement that applies drum-brake shoes. Leakage, sticking, improper mounting, or air entry can cause poor braking or uneven operation.

A self-adjuster compensates for lining wear to maintain correct shoe-to-drum clearance. A seized, misassembled, or incorrect adjuster can contribute to long pedal travel or reduced rear braking.

Brake shoes slide on designated backing-plate contact areas. Clean and lubricate only the points and lubricant specified by the manufacturer; never contaminate friction surfaces with lubricant.

Measure drum condition and dimensions with appropriate tools, then compare the results to the manufacturer's limits. Replace or machine the drum only when permitted by those specifications.

Use proper dust-control practices and personal protective equipment when servicing drum brakes. Inspect shoes, springs, retainers, adjusters, and related hardware together and install them in the correct orientation.

A floating caliper moves on slides or guide pins. Hydraulic force pushes the inboard pad, and caliper movement clamps the outboard pad; restricted slide movement can cause uneven pad wear.

A fixed caliper is mounted rigidly and uses opposed piston action to clamp pads against both rotor faces. Its diagnosis focuses on each piston, hydraulic passage, pad movement, and mounting condition.

Inspect pad thickness, friction material condition, contamination, glazing, cracks, and wear pattern. Compare inner and outer pads and use the vehicle manufacturer's minimum thickness and replacement criteria.

A seized or restricted slide can prevent a floating caliper from centering and can create uneven pad wear or pulling. Inspect guide pins, boots, mounting surfaces, and specified lubrication before condemning the caliper.

Lateral runout is side-to-side rotor movement measured as it rotates. Excessive runout can contribute to brake-pedal pulsation and can be caused by rotor, hub, mounting-surface, or wheel-bearing issues.

Thickness variation is an uneven rotor thickness around its circumference. It can cause a changing hydraulic displacement during braking and is evaluated against manufacturer specifications, not by appearance alone.

A rotor must remain at or above the manufacturer-specified minimum thickness after any permitted machining. Do not use a generic value; compare the measured result with the vehicle's published specification.

Uneven or excessive wheel-lug torque can distort components or affect runout measurements. Follow the correct pattern and torque specification when reinstalling a wheel before final verification.

Abutment clips, shims, and pad retainers position pads and control movement. Corrosion, wrong installation, or missing hardware can create noise, binding, or uneven wear.

Before retracting a caliper piston, follow the manufacturer's procedure and consider fluid level, electronic parking-brake design, and ABS/service requirements. A forced piston can damage a component or move contaminated fluid improperly.

A dragging disc brake may involve mechanical binding, a caliper issue, a hose restriction, or retained hydraulic pressure. Compare temperatures and test results safely, then isolate the cause using manufacturer procedures.

A pull can result from unequal braking force, tire or suspension concerns, or road conditions. Inspect the full system and measure rather than assuming the caliper on the pulling side is the cause.

Use scan-tool data with the manufacturer's procedure to compare relevant inputs, such as wheel-speed signals, during the reported condition. A signal discrepancy must be traced to its cause rather than treated as automatic proof of a failed sensor.

An antilock brake system modulates brake pressure when it detects wheel-lock tendencies, helping the driver retain steering control during hard braking. ABS does not eliminate the need for safe following distance or proper tires.

Wheel-speed sensors provide rotation information to the brake-control module. The module uses those signals to identify wheel-speed differences and command brake-pressure modulation when appropriate.

The hydraulic control unit contains valves and may contain a pump that lets the system increase, hold, or reduce hydraulic pressure at a wheel circuit. Its exact operation and service steps are vehicle-specific.

Verify the warning concern, inspect obvious wiring and component issues, retrieve diagnostic trouble codes, and follow the manufacturer's test routine. Clearing a code without finding its cause is not a repair.

A fault can disable an electronic brake-control function while leaving conventional hydraulic braking available, but warning behavior and failsafe operation vary by vehicle. Consult service information before driving or diagnosing further.

TCS manages excessive driven-wheel slip during acceleration. Depending on vehicle design, it may reduce engine output, apply braking at a spinning wheel, or use both strategies.

ESC compares driver input and vehicle motion signals to help mitigate understeer or oversteer. It can request selective braking and, on many vehicles, changes in engine torque.

ESC uses sensor inputs such as yaw rate, steering angle, wheel speed, and often lateral acceleration to compare intended vehicle path with actual motion. Calibrate or initialize sensors only as specified by the manufacturer.

Substantially different tire rolling diameters or incorrect tire pressures can produce unexpected wheel-speed relationships. Follow vehicle specifications for tire fitment and investigate sensor data before replacing electronic components.

After a repair, clear codes only when the procedure calls for it, confirm the concern is resolved, and complete required functional checks or road testing. Recheck for codes and warning lamps before returning the vehicle.