Automobile & Light Truck Certification Test A5 Brakes flashcards

A condition during brake drum machining where the friction surface becomes shiny and hard, indicating the cutting tool is rubbing rather than cutting cleanly, often due to improper lathe settings.

• Results in poor surface finish.
• Can be caused by insufficient depth of cut or incorrect feed/speed.
• Requires adjustment to lathe parameters for proper material removal.

Memory trick: Rubbing makes it shine, but cutting makes it fine!

The largest allowable internal diameter for a brake drum, typically stamped on the drum itself, beyond which the drum must be replaced for safety.

• Exceeding this limit compromises drum strength.
• Results in reduced braking effectiveness and potential failure.
• Always replace drums that exceed this specification.

Memory trick: Don't cross the red line, or your brakes will decline!

A common issue where an on-car brake lathe produces a rotor surface that is thicker on one side (inner or outer) than the other, often caused by underlying vehicle component issues.

• Indicates uneven material removal.
• Can lead to brake pulsation after machining.
• Often points to issues with wheel bearings or suspension components.

Memory trick: If the wheel wiggles, the rotor won't be even!

Vibrations that occur during machining, resulting in an uneven, wavy, or torn surface finish on the brake rotor or drum, often indicating instability in the lathe setup or cutting process.

• Can be caused by dull tools, improper settings, or loose components.
• Leads to poor braking performance and noise.
• Requires careful diagnosis of the entire machining system.

Memory trick: If the setup wobbles, the cut gobbles!

Localized areas of increased hardness in a brake drum's friction surface, often caused by extreme heat, which can lead to chatter during machining and uneven braking.

• Caused by localized overheating and material transformation.
• Difficult to machine smoothly.
• Requires specific lathe settings to overcome.

Memory trick: Slow and deep beats fast and shallow for tough spots!

A condition where the main rotating component (spindle/arbor) of a brake lathe is not perfectly straight or aligned, leading to consistent errors like tapered cuts, regardless of workpiece mounting.

• Causes persistent dimensional inaccuracies.
• Requires professional repair or replacement of lathe components.
• Cannot be corrected by adjusting workpiece mounting or cutting parameters.

Memory trick: If the core is crooked, every cut is a crooked look it!

The smallest allowable thickness for a brake rotor, typically stamped on the rotor, below which the rotor must be replaced due to compromised structural integrity and heat dissipation capabilities.

• Exceeding this limit reduces heat capacity and strength.
• Can lead to warping, cracking, or brake fade.
• Always replace rotors that are at or below this specification.

Memory trick: Measure twice, cut once, and make sure there's enough to cut!

A brake rotor or drum surface finish characterized by visible, fine concentric grooves, resembling an old vinyl record, often caused by an improper (usually too high) feed rate during machining.

• Indicates an uneven surface at a microscopic level.
• Can lead to premature pad wear or noise.
• Requires adjustment of lathe feed rate for correction.

Memory trick: Fast feed, fancy grooves, but not for your brakes!

The amount of lateral deviation or wobble in the friction surface of a brake drum as it rotates, which can cause pulsation, noise, and uneven pad wear if excessive.

• Measured with a dial indicator.
• Can be caused by improper mounting, warped drums, or worn bearings.
• Must be corrected before machining for a quality finish.

Memory trick: Is it seated right? If not, it's not straight!

The final, very light cut taken during brake rotor machining, designed to create a smooth, non-directional surface texture essential for proper brake pad seating and optimal braking performance.

• Uses a minimal depth of cut.
• Aims for a specific surface finish (non-directional).
• Crucial for preventing brake noise and ensuring proper pad break-in.

Memory trick: The final polish for a perfect pad hug!

A rupture or tear in the flexible diaphragm inside a vacuum brake booster, causing a vacuum leak.

• Leads to reduced or no power assist (hard pedal).
• Can cause engine idle issues (rough idle, stalling) if the leak is significant.
• Often accompanied by a hissing sound from the pedal area.

Memory trick: Engine 'sucks' extra air through the leak, making it stumble.

A flexible rubber membrane inside the vacuum brake booster that separates the vacuum and atmospheric pressure chambers, allowing for pressure differential to assist braking.

• Separates booster chambers.
• Crucial for creating pressure differential.
• Rupture or leak causes loss of assist (hard pedal).

Memory trick: Hard pedal, good vacuum? The booster's diaphragm is probably undone!

A service procedure for electronic brake systems to ensure accurate correlation between pedal input (position/force) and the produced hydraulic brake pressure.

• Crucial for consistent brake feel and performance.
• Required after component replacement or system updates.
• Ensures accurate electronic interpretation of driver input.

Memory trick: Calibrate to match the foot's 'speak' to the brake's 'listen'.

A one-way valve located on the vacuum booster that maintains vacuum within the booster when the engine is off or manifold vacuum is low, ensuring power assist is available.

• Prevents vacuum loss from the booster.
• Essential for initial brake assist when starting the engine.
• Failure leads to hard pedal or no power assist.

Memory trick: Press, Start, Drop. If no drop, check the valve, then booster's a flop!

A condition where hydraulic fluid bypasses the piston seals within the master cylinder, preventing full pressure buildup and causing the brake pedal to slowly sink.

• Pedal sinks slowly under steady pressure.
• Often no external fluid leaks.
• Indicates worn or damaged piston seals.

Memory trick: Pedal sinks slow, master cylinder's seals let the fluid flow!

The foot-operated valve in an air-over-hydraulic brake system that controls the flow of compressed air to the air-over-hydraulic slave cylinders.

• Directly controls brake application and release via air pressure.
• Malfunction can cause both hard pedal and slow release.
• Crucial for proportionate braking control.

Memory trick: Treadle valve is the 'air faucet' for the brakes; if it's stuck, flow is bad.

A power brake assist system that uses hydraulic pressure from the power steering pump instead of engine vacuum to amplify brake pedal force.

• Uses power steering pump for pressure.
• Assists both braking and steering.
• Pump failure affects both systems.

Memory trick: Hydro-Boost shares the pump's might, if it fails, both systems fight!

Any blockage or kink in the vacuum line supplying the brake booster, which limits the rate at which vacuum can be drawn into the booster.

• Restricts vacuum flow to booster.
• Causes loss of assist after rapid pedal applications.
• Can be due to collapsed hose or carbon buildup.

Memory trick: Rapid pumps, hard pedal? Vacuum hose restriction, don't meddle!

A tear or hole in the flexible membrane inside a vacuum brake booster, leading to a vacuum leak, loss of power assist, and often a hissing sound.

• Causes loud hiss from pedal area.
• Results in hard brake pedal.
• Creates a large vacuum leak, affecting engine idle.

Memory trick: Hissing, hard pedal, idle drop? Diaphragm's ruptured, make it stop!

A malfunction of an electrically operated pump designed to augment or provide vacuum for the brake booster, especially in vehicles with low engine vacuum.

• Leads to a hard brake pedal due to insufficient vacuum assist.
• Symptoms are more pronounced on cold starts or under specific driving conditions.
• Requires checking pump operation and its electrical circuit.

Memory trick: Electric pump is the 'vacuum maker'; if it stops, vacuum 'starves'.

A valve within the power steering pump that regulates hydraulic fluid flow and pressure, supplying both the power steering gear and the hydro-boost brake unit.

• Crucial for proper operation of both steering and hydro-boost.
• Malfunction can cause reduced assist to both systems simultaneously.
• Often a spring-loaded plunger that diverts flow.

Memory trick: Two systems, one pump, one shared valve. If one fails, both suffer.

An integrated electro-mechanical unit that provides brake pedal assist and often incorporates ABS/ESC functions, replacing traditional vacuum or hydro-boost systems.

• Uses an electric motor for assist.
• Highly integrated unit.
• Internal faults often require full assembly replacement.

Memory trick: i-Booster's motor fault? It's a full assembly vault!

A diagnostic trouble code indicating an internal failure within the Electric Power Assist Steering (EPAS) control module, typically requiring replacement of the module.

• Indicates hardware failure of EPAS module.
• Often results in loss of power assist (heavy steering).
• Usually requires module/motor assembly replacement.

Memory trick: C0550: The EPAS brain is fried, no fix, just replace, don't hide!

A component in a hydro-boost brake system that stores hydraulic pressure, allowing for power-assisted braking after the engine is turned off.

• Stores hydraulic pressure.
• Provides reserve brake assist.
• Typically spring-loaded or gas-charged.

Memory trick: The accumulator's like a battery, saving power for when the engine's off, you see!

A diagnostic trouble code indicating an electrical fault within the circuit of an Electric Power Steering (EPS) system's position sensor.

• Often caused by wiring issues, loose connectors, or sensor failure.
• Leads to intermittent or complete loss of power assist.
• Requires inspection of the circuit before component replacement.

Memory trick: DTCs point to circuits; circuits mean wires and connectors first.

A system that uses an electric motor to drive a hydraulic pump, providing power assist for steering and sometimes braking, independent of engine speed.

• Electric motor drives hydraulic pump.
• Can provide assist to both steering and braking.
• Failure of electric pump affects both systems.

Memory trick: The electric heart of EHPAS, if it stops, steering and brakes are in a pass.

Initial diagnostic steps for heavy steering in an Electric Power Steering system, starting with basic mechanical checks before electrical diagnostics.

• Rule out non-EPS issues first.
• Check tire pressure and alignment.
• No fluid in EPS systems.

Memory trick: Heavy steering, no lights? Check tires and alignment, make it right!

A brake assist system that uses an electric motor-driven hydraulic pump to provide power braking, eliminating reliance on engine vacuum.

• Common in hybrid/electric vehicles and some gasoline vehicles.
• Provides consistent brake assist regardless of engine vacuum.
• Often integrates ABS, traction control, and stability control functions.

Memory trick: EHPB is electric, not engine vacuum – like a 'battery-powered' brake.

A condition where the vacuum supply to the brake booster is impeded, leading to reduced power assist and a hard brake pedal.

• Causes increased pedal effort, especially after multiple applications.
• Can be due to a collapsed or kinked vacuum hose, or a faulty check valve.
• Engine vacuum may be good, but booster vacuum recovery is slow.

Memory trick: Hard pedal, low vacuum recovery means a 'tight' vacuum line.

Air trapped within the hydraulic brake fluid, which is compressible unlike fluid, leading to a soft or spongy brake pedal feel.

• Causes a spongy or soft pedal.
• Pedal feel may improve with rapid pumping.
• Requires bleeding the brake system to remove.

Memory trick: Soft pedal, puff of air, pump to firm it fair.

Air trapped within the hydraulic brake system, which is compressible and reduces braking efficiency, causing a spongy pedal feel.

• Causes spongy pedal
• Pedal can improve with pumping
• Requires bleeding to remove

Memory trick: Spongy pedal, pump it up, air's the culprit, clear it out!

Adding too much brake fluid to the reservoir, exceeding the maximum fill line, which can occur during improper service.

• Common cause is human error
• Can lead to fluid overflow when pads wear
• Does not directly cause brake issues if not severe

Memory trick: Fluid's high, no issues? Just an overfill, no need for tissues!

A tear or hole in the rubber diaphragm within the brake booster, preventing it from holding vacuum and providing power assist to the brake pedal.

• Causes hard pedal
• Increases stopping effort
• Often due to age or material degradation

Memory trick: Hard pedal, no vacuum assist, booster's diaphragm is probably missed!

Brake fluid is hygroscopic, meaning it absorbs moisture from the atmosphere. Water contamination significantly lowers the fluid's boiling point. When brake fluid boils due to high temperatures from braking, it forms compressible vapor bubbles, leading to a 'spongy' or 'mushy' pedal and reduced braking effectiveness, known as brake fade.

• Hygroscopic nature.
• Absorbs water over time.
• Water lowers boiling point.
• Boiling creates compressible vapor.

Memory trick: When the fluid's boiling point takes a dive, your brake pedal won't feel alive!

Malfunction of the electric pump motor within the ABS Hydraulic Control Unit (HCU), preventing proper pressure modulation during anti-lock braking events.

• Causes 'hard pedal' during active ABS.
• ABS warning light may activate during events.
• Conventional braking may remain normal.

Memory trick: ABS light on, pedal hard, pump motor failed in the yard.

The process of pre-bleeding a new master cylinder on a workbench to remove air from its internal passages before installation, ensuring proper function.

• Prevents air from entering the system upon installation.
• Uses short hoses to cycle fluid back into the reservoir.
• Hoses must remain submerged to avoid drawing in air.

Memory trick: Tubes must dive, to keep air alive (out).

A hydraulic valve in the brake system that limits the amount of fluid pressure reaching the rear brakes during hard braking.

• Prevents premature rear wheel lock-up.
• Reacts to sudden pressure increases.
• Works by restricting fluid flow to the rear circuit after a certain pressure threshold.

Memory trick: Proportioning: 'P' for Prevent rear lock-up.

The brake fluid level in the reservoir naturally drops as brake pads wear because the caliper pistons extend, drawing fluid into the calipers. Adding fluid before replacing pads can lead to overfilling.

• Low fluid due to pad wear is normal
• Add fluid AFTER pad replacement
• Overfilling can cause overflow or issues

Memory trick: Pads wear down, fluid goes low, replace the pads, then let the fluid flow!

A two-stage flare used on hydraulic brake lines to create a strong, leak-proof seal, common in domestic and Asian automotive applications.

• Creates a double wall for strength
• Used with inverted flare fittings
• Standard for high-pressure brake lines

Memory trick: For brake lines, double up the flare, for safety and pressure beyond compare!

During manual brake bleeding, if the bleeder screw is not sufficiently tightened, air can be drawn into the brake caliper or wheel cylinder around the threads when the brake pedal is released, giving a false indication of air still being present in the hydraulic system.

• Occurs during manual bleeding.
• Bleeder screw not tight enough.
• Draws air in on pedal release.
• Produces persistent small bubbles.

Memory trick: Bleeder screw's loose, air's a goose!

A pressure differential valve (or warning switch) is a safety device in dual-circuit brake systems that detects a pressure loss in one circuit and activates a warning light on the dashboard.

• Monitors pressure in both primary and secondary brake circuits.
• Contains a piston that shifts when pressure imbalance occurs.
• Shifting piston activates an electrical switch.
• Illuminates the brake system warning light for the driver.

Memory trick: Differential pressure lights up the danger signal.

The proportioning valve, often part of a combination valve, reduces hydraulic pressure to the rear brakes during heavy braking. This prevents premature rear wheel lock-up caused by the forward weight transfer, ensuring stable and controlled deceleration.

• Reduces rear brake pressure.
• Activates during heavy braking.
• Prevents rear wheel lock-up.
• Compensates for weight transfer.

Memory trick: Rear wheels lock, the proportioning valve's clock is stuck!

A persistent leak at a brake line connection, despite proper tightening and correct thread engagement, often indicates a defect in the double flare itself. This could be a crack, an uneven surface, or an incorrect angle, preventing a complete hydraulic seal against the mating fitting.

• Leak after tightening.
• Threads on easily.
• Flare is the sealing surface.
• Cracked or uneven flare.

Memory trick: The flare's the face, if it's not smooth, the fluid finds its escape proof!

The complex internal design of an ABS Hydraulic Control Unit (HCU) can trap air that is resistant to removal by conventional manual or pressure bleeding methods. This results in a persistent spongy brake pedal, often requiring a scan tool to activate the ABS pump and valves for proper bleeding.

• Spongy pedal persists.
• Conventional bleeding fails.
• HCU's complex passages.
• Requires scan tool for ABS cycle.

Memory trick: Bleeding's done, but the pedal's still soft; the HCU's got air, it's aloft!

Specialized bleeding procedures required for brake calipers designed to minimize pad-to-rotor contact when brakes are not applied, often involving piston manipulation.

• Piston slightly retracts after pedal release.
• Can trap air if bled conventionally.
• May require specific manufacturer-recommended piston cycling during bleeding.

Memory trick: Low-drag calipers need tricky bleeds.

The electric pump within the ABS Hydraulic Control Unit that is responsible for returning brake fluid from the wheel circuits to the master cylinder during an ABS event and assisting in pressure control.

• Recycles fluid during ABS activation.
• Maintains hydraulic pressure within the ABS system.
• Failure can cause various brake symptoms, including a hard pedal if it creates a restriction.

Memory trick: ABS hard pedal? HCU pump might be jammed.

A flexible brake hose can internally collapse, acting as a check valve that allows fluid to flow to the caliper but restricts its return, leading to a dragging brake.

• Internal layers of the hose separate or swell.
• Fluid can pass under pressure (pedal applied).
• Return flow is blocked or restricted when pressure drops.
• Causes a dragging brake on the affected wheel.

Memory trick: Dragging brake on one wheel? Check the hose, it might be choking.

A condition where brake fluid bypasses the piston seals within the master cylinder, preventing pressure buildup and causing the brake pedal to slowly sink.

• Pedal sinks slowly under steady pressure.
• No external fluid loss.
• Caused by worn primary cup seal.

Memory trick: Pedal sinks slow, master cylinder's flow, seals won't go.

Corrosion on steel brake lines, particularly pitting and rust scale, weakens the line's structural integrity. This significantly increases the risk of a sudden rupture during braking, leading to a rapid loss of hydraulic pressure and potential brake failure. It is a critical safety concern requiring immediate replacement.

• Weakens line integrity.
• High risk of sudden rupture.
• Leads to loss of hydraulic pressure.
• Causes brake failure.

Memory trick: Rust on the line, a ticking bomb's sign!

A diagnostic test for vacuum brake boosters where the pedal is held down with the engine off, then the engine is started. A functional booster will cause the pedal to drop slightly.

• Checks for proper vacuum assistance.
• Pedal should drop when engine starts.
• No drop indicates booster or vacuum issue.

Memory trick: Hard pedal, no drop, booster's a flop.

DOT 4 and DOT 5.1 brake fluids are both glycol-ether based and are fully compatible with each other and with systems designed for DOT 3, 4, or 5.1.

• DOT 3, DOT 4, and DOT 5.1 are glycol-ether based.
• These fluids are hygroscopic and compatible with each other.
• DOT 5 is silicone-based and NOT compatible with other DOT fluids.
• Higher DOT numbers (4, 5.1) generally indicate higher boiling points.

Memory trick: Glycol fluids mix, but silicone stands alone.

A malfunction of the electric pump motor within the ABS Hydraulic Control Unit, which is responsible for maintaining and modulating brake fluid pressure during ABS events.

• Causes issues specifically during ABS activation
• Can result in a hard pedal or poor ABS performance
• Often accompanied by ABS warning light

Memory trick: ABS pedal's hard, pump motor's tired, pressure control is now misfired!

Over time, brake fluid's additives (especially corrosion inhibitors) degrade, and it absorbs moisture. This combination leads to internal corrosion of metal hydraulic components (like the master cylinder bore and caliper pistons) and breakdown of rubber seals, resulting in dark, sludgy, and contaminated fluid.

• Fluid additives degrade.
• Moisture absorption.
• Causes internal corrosion.
• Breaks down rubber seals.

Memory trick: Dark fluid, like a muddy bog, means internal rust and components log!

Degradation of steel brake lines due to rust and environmental exposure, leading to reduced strength and potential leaks.

• Pitting corrosion is more dangerous than surface rust.
• Compromises hydraulic pressure integrity.
• Requires replacement, not repair, for safety.

Memory trick: Brake lines: if it's pitted, it's quitting.

A ruptured brake booster diaphragm prevents the booster from holding vacuum and creating the necessary pressure differential to assist braking, resulting in a 'hard' brake pedal.

• Brake boosters use engine vacuum to assist braking.
• The diaphragm separates atmospheric pressure from vacuum.
• A rupture allows vacuum to escape, neutralizing the assist.
• Symptom: hard brake pedal requiring excessive force.

Memory trick: Hard pedal + no vacuum hold = a 'hole' in the booster.

A safety valve that monitors pressure balance between the primary and secondary brake circuits and illuminates a warning light if a significant pressure difference is detected.

• Indicates a hydraulic pressure loss in one circuit.
• Does not stop the leak, only warns the driver.
• Often integrated into a combination valve.

Memory trick: Warning light: Low fluid, parking brake, or pressure imbalance.

A blockage or collapse within a brake line, preventing the proper flow of hydraulic fluid to the brake component it serves.

• Can be caused by corrosion or internal damage
• Prevents fluid from reaching caliper/wheel cylinder
• Leads to lack of braking at affected wheel or difficulty bleeding

Memory trick: Firm pedal, no fluid's flow, restricted line is the pathway's woe!

To diagnose an internally collapsed flexible brake hose causing delayed brake release, clamp the suspect hose with vice grips (or a specialized brake line clamp). Depress the brake pedal. If the pedal becomes significantly firmer than before, it suggests the hose was the culprit, as the clamp is mimicking its internal restriction and preventing fluid return.

• Causes delayed brake release.
• Acts as a one-way valve.
• Clamping restricts fluid.
• Pedal feels firmer if good.

Memory trick: Clamp the hose, feel the squeeze; if the pedal's firm, you're at ease (with your diagnosis).

A restricted brake line or hose impedes the flow of hydraulic fluid, leading to symptoms such as inconsistent fluid flow during bleeding, pulling to one side during braking, or a wheel dragging after pedal release. This occurs despite normal system pressure.

• Inconsistent fluid flow.
• Steady pressure applied.
• Can be hard line or flexible hose.
• Causes uneven braking.

Memory trick: Fluid's trying to pass, but a hidden block's in its class.

Reasons why a flare nut connection on a brake line might leak, focusing on installation errors.

• Proper torque is crucial for a leak-free seal.
• Under-tightening allows seepage.
• Over-tightening can damage the flare itself.

Memory trick: Flare leaks: too loose to seal, or too tight to hold.