ASE A5 Brakes Practice Test
This is a free 15-question sampler on ASE A5, the brakes test, written by the StudyPDF team. It covers hydraulic system diagnosis, brake fluid, drum brakes, disc brakes, power assist units, wheel bearings, parking brakes and electronic brake control, mixing multiple choice, select all that apply and fill in the blank. Answer all 15 questions, then check your score and read the explanation for every question.
A dual, or split, master cylinder is used so that:
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Prefer to read before you play? Every question in the sampler is listed below. Answers and explanations stay collapsed until you open them.
1. A dual, or split, master cylinder is used so that:
- A. the pedal takes less effort to push
- B. the rear brakes always get the same pressure as the front brakes
- C. a leak in one circuit still leaves the other circuit able to stop the vehicle
- D. the brake fluid never has to be replaced
Show answer and explanation
Answer: C. a leak in one circuit still leaves the other circuit able to stop the vehicle
A dual master cylinder has two pressure chambers feeding two separate circuits, split either front to rear or diagonally. Lose one circuit and the other still works, but only about half the braking is left, the pedal travels much farther before it does anything, and the stopping distance grows. A pressure differential switch senses the imbalance and turns on the brake warning lamp, so a warning lamp with a long pedal is a failed circuit to be found, never a top off job.
2. Complete the sentence.
Brake fluid meeting DOT 3 and DOT 4 is hygroscopic, which means it absorbs _____ from the air over time. That lowers the fluid's _____, so hard repeated braking can boil it and leave the pedal soft just when it is needed most.
Options for blank 1: moisture, heat, copper, oxygen
Options for blank 2: viscosity, color, boiling point, freezing point
Show answer and explanation
Answer: moisture, boiling point
Glycol based fluid pulls water vapor in through hoses, seals and the reservoir cap, and even a small percentage of water drops the boiling point sharply. Liquid fluid does not compress, but the vapor bubbles that form when it boils do, which is why fluid that was fine on flat roads can give a long soft pedal on a mountain descent. That is the whole reason manufacturers publish a fluid replacement interval by time rather than by mileage.
3. Which of the following statements about brake fluid are true?
Select all that apply.
- A. DOT 3 and DOT 4 are glycol based and pull moisture out of the air
- B. Water absorbed by the fluid raises its boiling point
- C. DOT 5 is silicone based and must not be mixed with DOT 3 or DOT 4
- D. Spilled glycol based fluid can damage painted surfaces
- E. An opened container of brake fluid can sit uncapped on the bench with no effect on it
Show answer and explanation
Answer: A. DOT 3 and DOT 4 are glycol based and pull moisture out of the air, C. DOT 5 is silicone based and must not be mixed with DOT 3 or DOT 4, D. Spilled glycol based fluid can damage painted surfaces
DOT 3, DOT 4 and DOT 5.1 are glycol based and hygroscopic. DOT 5 is silicone, does not absorb water and is not compatible with the glycol fluids, so mixing them is a system contamination, not a top off. Water lowers the boiling point rather than raising it. Glycol fluid strips paint, so wipe spills immediately and flush with water. And an open container starts absorbing moisture right away, which is why you use fluid from a sealed container and cap what is left.
4. A brake pedal feels soft and springy, and it firms up when the driver pumps it. This most often means:
- A. air is trapped in the hydraulic system
- B. the master cylinder seals are bypassing internally
- C. the rotors have excessive lateral runout
- D. the parking brake cable is seized
Show answer and explanation
Answer: A. air is trapped in the hydraulic system
Brake fluid does not compress, so a pedal that squashes has something in it that does, and that is air. Pumping compresses the trapped air enough to move fluid to the wheels, which is why the pedal firms up on the second and third push. Bleeding fixes the symptom, but find how the air got in first, because a hose, a loose fitting or a low reservoir that let the master cylinder suck air will simply put it back.
5. Stopped at a light with steady foot pressure, the pedal slowly sinks toward the floor. There is no fluid on the ground and no wet spot at any wheel. The most likely cause is:
- A. rotors with excessive thickness variation
- B. a metering valve stuck open
- C. glazed brake linings
- D. master cylinder cup seals letting fluid bypass inside the cylinder
Show answer and explanation
Answer: D. master cylinder cup seals letting fluid bypass inside the cylinder
A pedal that sinks under constant pressure means fluid is going somewhere. With no external leak, it is going past the master cylinder cup seals and back into the reservoir, so the level can look perfectly normal. Keep this separate from the spongy pedal: spongy and pumps up points at air, slowly sinking under steady pressure points at the master cylinder. Rotor and lining problems change how the vehicle stops, not whether the pedal holds.
6. Complete the sentence.
A _____ valve limits how much pressure reaches the rear brakes during a hard stop, so the lighter loaded rear wheels do not lock before the fronts. A _____ valve holds pressure back from the front disc brakes at low pedal effort, so the rear drum shoes have time to overcome their return springs.
Options for blank 1: metering, residual pressure, proportioning, check
Options for blank 2: metering, proportioning, bypass, load sensing
Show answer and explanation
Answer: proportioning, metering
Both often live inside one combination valve along with the pressure differential switch that lights the brake warning lamp. The proportioning valve exists because weight shifts forward under braking and the rear tires lose grip. The metering valve exists because disc brake pads sit almost touching the rotor while drum shoes have to be pulled off their return springs first, so without it the front would grab before the rear did anything. Many newer vehicles handle rear pressure electronically through the ABS module instead of with a mechanical valve.
7. No manufacturer bleeding sequence is available for a vehicle. Common practice is to start bleeding at the wheel farthest from the master cylinder and work toward the closest. The usual reason given is that:
- A. the farthest wheel has the highest pressure in it
- B. the longest line holds the most air, so clearing it first avoids pushing fluid back through circuits you already finished
- C. the rear brakes need less fluid than the front brakes
- D. starting at the closest wheel would damage the master cylinder
Show answer and explanation
Answer: B. the longest line holds the most air, so clearing it first avoids pushing fluid back through circuits you already finished
The point of a sequence is to move air out in an orderly way instead of chasing it around the system. Two things matter more than the habit itself. The manufacturer's published sequence always wins where one exists, and on many vehicles with ABS the module has to be commanded through a bleed routine with a scan tool or trapped air will never come out of it. Also bench bleed a new master cylinder before installing it, because air sitting in the cylinder bore is very hard to push out afterward.
8. A pulsation felt in the brake pedal only while braking is most directly caused by:
- A. excessive lateral runout of the rotor
- B. thickness variation across the rotor
- C. air trapped in the caliper
- D. a worn wheel bearing
Show answer and explanation
Answer: B. thickness variation across the rotor
Thickness variation means the rotor is measurably thicker in some spots than others. As the thick spot passes between the pads, the caliper piston is pushed back, and that motion travels up the fluid column into your foot. Lateral runout is side to side wobble measured with a dial indicator, and by itself it does not move the pedal. It matters because the wobbling high spot keeps brushing the pads between stops and grinds thickness variation into the rotor over the following weeks, so runout found today is pulsation a month from now. Check runout with a dial indicator and thickness variation with a micrometer at several points around the rotor.
9. On a floating caliper disc brake, the inboard pad is worn far more than the outboard pad. The most likely cause is:
- A. brake fluid that is past its replacement interval
- B. a restricted proportioning valve
- C. caliper slides or bushings that are binding, so the caliper cannot move on its mounts
- D. a rotor that is below minimum thickness
Show answer and explanation
Answer: C. caliper slides or bushings that are binding, so the caliper cannot move on its mounts
A floating caliper has pistons on the inboard side only. The piston pushes the inboard pad against the rotor, and the reaction force slides the whole caliper body inward to pull the outboard pad in behind it. If the slides are dry, corroded or have swollen bushings, the caliper cannot move, so the inboard pad does nearly all the work and wears out first. Clean and lubricate the slides with the specified high temperature grease whenever pads are replaced. A different pattern, both pads worn and the wheel hot after a drive, points at a piston or a hose that is not releasing.
10. On many duo-servo drum brakes, when does the star wheel self adjuster take up lining wear?
- A. Every time the brakes are applied while moving forward
- B. Only when the drum is removed and the star wheel is turned by hand
- C. Whenever the engine is started
- D. When the brakes are applied while the vehicle is backing up
Show answer and explanation
Answer: D. When the brakes are applied while the vehicle is backing up
In that design the shoes float around slightly during a reverse stop, and that movement lets the adjuster lever climb one tooth and turn the star wheel. It is why a vehicle that is always parked nose out can develop a low pedal from underadjusted rear brakes, and why backing up and stopping a few times is a standard step after a drum brake job. Other designs advance the adjuster through the parking brake linkage instead, so on those the parking brake going unused causes the same low pedal. Either way, a self adjuster that is seized, installed on the wrong side or missing its spring stops adjusting entirely.
11. In a duo-servo drum brake, which shoe does most of the stopping work when the vehicle is moving forward?
- A. The secondary shoe, the one toward the rear of the vehicle
- B. The primary shoe, the one toward the front of the vehicle
- C. Both equally, because the wheel cylinder pushes them with the same force
- D. Neither, because the parking brake strut carries the load
Show answer and explanation
Answer: A. The secondary shoe, the one toward the rear of the vehicle
The wheel cylinder pushes both shoes out with equal force, but the drum is turning. It drags the primary shoe along with it, and that force passes through the adjuster link at the bottom into the secondary shoe, wedging it harder into the drum. This self energizing action is where duo-servo gets its stopping power. It is also why the secondary lining is usually the longer of the two, so on reassembly the shorter lining goes toward the front of the vehicle. Swap them and the brakes will feel weak and the linings will wear unevenly.
12. Which steps belong in a basic function test of a vacuum brake booster?
Select all that apply.
- A. With the engine off, press and release the pedal several times to use up any stored vacuum
- B. Bleed the hydraulic system before any booster test can be considered valid
- C. Hold steady pressure on the pedal and start the engine, expecting the pedal to drop slightly
- D. Run the engine about a minute, shut it off, wait a minute, then check that the first one or two applications still feel assisted
- E. Turn the master cylinder pushrod in until the pedal feels hard
- F. Unplug a wheel speed sensor to isolate the booster from the ABS module
Show answer and explanation
Answer: A. With the engine off, press and release the pedal several times to use up any stored vacuum, C. Hold steady pressure on the pedal and start the engine, expecting the pedal to drop slightly, D. Run the engine about a minute, shut it off, wait a minute, then check that the first one or two applications still feel assisted
The three real checks are depleting the reserve, watching for the pedal to drop when the engine supplies vacuum, and then testing whether the booster holds a reserve after shutdown. A pedal that does not drop means the booster is not getting vacuum or is not working, so check the hose and the check valve before condemning it. A booster that assists while running but has no reserve after shutdown usually has a leaking check valve or a leaking diaphragm. Pushrod length is a measured adjustment, not something you turn in until the pedal feels right, because a rod that is too long keeps the master cylinder ports covered and the brakes drag.
13. The main purpose of an antilock brake system is to:
- A. shorten the stopping distance on every road surface
- B. remove the need to bleed the base brake system
- C. keep the wheels from locking so the driver can still steer during hard braking
- D. apply the brakes automatically when the driver reacts too slowly
Show answer and explanation
Answer: C. keep the wheels from locking so the driver can still steer during hard braking
ABS senses a wheel about to lock and releases, holds and reapplies pressure at that wheel many times a second, which is the pulsing the driver feels. A rolling tire can still be steered, while a locked one just slides wherever momentum takes it. On loose gravel or deep snow a locked wheel builds a wedge of material ahead of it, so ABS can actually lengthen the stop there even though control is better. Two other points the test likes: ABS sits on top of the base brakes and cannot make up for worn pads or air in the lines, and automatic emergency braking is a separate system that happens to use the same hydraulic hardware.
14. One wheel speed sensor circuit is suspected on a vehicle with ABS. Which checks belong in that diagnosis?
Select all that apply.
- A. Replace the master cylinder before testing the sensor
- B. Measure the sensor's resistance and compare it with the specification
- C. Inspect the tone ring for chipped or missing teeth and for packed debris
- D. Check the brake fluid level, because low fluid switches the wheel speed sensors off
- E. Measure AC voltage at the sensor terminals while turning the wheel by hand
Show answer and explanation
Answer: B. Measure the sensor's resistance and compare it with the specification, C. Inspect the tone ring for chipped or missing teeth and for packed debris, E. Measure AC voltage at the sensor terminals while turning the wheel by hand
A passive wheel speed sensor is a coil and a magnet. Spin the ring past it and it generates its own small alternating voltage, so a meter set to AC volts while you turn the wheel tells you whether it is producing a signal at all, and a resistance reading compared with spec tells you whether the winding is open or shorted. Just as important, a perfect sensor reads erratically if the tone ring is damaged or packed with rust and debris, so inspect the ring before condemning the sensor. Active sensor designs are powered and need a scan tool or an oscilloscope instead, so confirm which type you have first.
15. Complete the sentence.
A serviceable tapered roller wheel bearing is set by turning the hub while tightening the nut, which seats the rollers against their races. The nut is then backed off and retightened to leave a small amount of _____. Going tighter than that puts the bearing into _____, which makes it run hot and fail early.
Options for blank 1: endplay, preload, runout, taper
Options for blank 2: float, endplay, preload, backlash
Show answer and explanation
Answer: endplay, preload
Turning the hub while you tighten is what makes the adjustment repeatable, because it forces the rollers into place instead of leaving them cocked. Always follow the manufacturer's procedure and torque values, and always use a new cotter pin. A bearing that is too loose gives excessive play at the top and bottom of the tire and a noise that changes when the vehicle is swerved gently side to side, since cornering loads and unloads each side. A bearing that is too tight has no room for oil film or heat growth and will fail quickly. Sealed hub units are not adjustable, so on those you measure play and replace the unit.
What the ASE A5 Brakes test covers
A5 is one test in the A series for automobile and light truck technicians, set by the National Institute for Automotive Service Excellence. It stays inside the brake system: hydraulic system diagnosis and repair, drum brakes, disc brakes, power assist units, wheel bearings and parking brakes, and electronic brake control systems such as ABS and the stability systems built on top of it. These are hydraulic brakes on cars and light trucks. Air brakes on commercial vehicles are not part of A5, they sit in the medium and heavy truck series, so a CDL air brakes study guide is the wrong book for this test.
Certification takes two things, not one. You pass the test, and you show two years of hands on work experience. Relevant formal training can stand in for part of that experience, and ASE publishes the current rules for how much. Certification also does not last forever. It expires and you retest to keep it current, which is why the technicians around you talk about recertifying rather than about having certified once.
The test day numbers move, so this page will not quote them. How many questions you get, how long you have, what score passes, what registration costs and which testing windows are open are all set by ASE and updated over time. Take those from ASE directly or from your own registration confirmation, and treat any practice site that states them as possibly out of date.
One thing worth knowing before you start studying is the flavor of the questions. A5 leans hard on diagnosis rather than recall, and a good share of items are written as Technician A says one thing, Technician B says another. Naming the parts is not enough. You have to know what symptom each failure actually produces, and which of two plausible sounding explanations fits the evidence given.
How to use this sampler
These 15 questions spread across the A5 content areas rather than drilling one of them. There are hydraulic questions on the split master cylinder, brake fluid and pedal feel, drum questions on the duo-servo layout and the self adjuster, disc questions on rotor condition and floating caliper wear, a power assist question, a wheel bearing question and two on electronic brake control. They ask why a symptom happens, not just what a part is called, because that is what the real test does.
Take it in one sitting without notes, then read the explanation for every question, including the ones you got right. Treat a wrong answer as a topic rather than a fact. If you missed the pulsation question and the caliper wear question, sit down with disc brake service as a whole instead of memorizing two answers.
The most useful study habit for A5 is learning symptoms in pairs, because that is how the test separates people who have read a book from people who have done the work. A spongy pedal and a slowly sinking pedal are not the same complaint. A pulsation and a pull are not the same complaint. Rotor runout and rotor thickness variation are measured with different tools and cause different things. Once you can say the pair out loud in your own words, the Technician A and Technician B questions stop being tricky.
Then go put your hands on the hardware. Pull a drum, work a star wheel adjuster, flex a caliper slide, watch a pedal drop when an engine starts. Brakes is one of the areas where five minutes at a vehicle fixes a misunderstanding that an hour of reading did not.
How StudyPDF builds full practice tests from your own material
Fifteen questions can show you which parts of the brake system you cannot yet explain. They cannot get you ready on their own, and a generic question bank does not know which study guide you are working from or which areas your shop rarely sees.
StudyPDF works from your material instead. You upload your A5 study guide, the brakes chapter of a service manual, or the handouts from your training program, and Bo, the study agent, builds full-length practice tests from those exact pages. Every question is grounded in your document, and every explanation points back to where the answer came from, so you can check the wording yourself when two sources seem to disagree. You can regenerate fresh tests as often as you like, narrow one to a single area such as ABS diagnosis or drum brake service, and track which topics you keep missing.
You do not need a file to start. If your study guide is at the shop, just name a topic instead, for example hydraulic brake diagnosis or disc brake service, and Bo writes a practice test from that. Starting is free.
Written by the StudyPDF team. Last updated 2026-08-19.