22 A5 — Brakes Practice Questions & Answers

1. 1. A vehicle has a firm brake pedal that slowly sinks toward the floor while steady pressure is held at a stop. The fluid level is normal and no external leaks are found anywhere in the system. What is the most likely cause?

   • A.Air trapped in one caliper bore compressing under the held pedal
   • B.Rear drum self-adjusters failing to take up the lining clearance
   • C.A flexible hose ballooning and absorbing pedal travel at a wheel
   • D.Fluid bypassing internally past the master cylinder piston cups✓ Answer

   When the cups inside the master cylinder no longer seal, fluid bypasses the piston and returns to the reservoir instead of holding pressure, so the pedal creeps toward the floor even though nothing leaks outside. The fluid level stays normal because the fluid never leaves the system.

   Source: ASE Automobile Study Guide, Brakes (A5) task list - master cylinder diagnosis and repairReport a problem with this question

2. 2. With the engine off, a technician pumps the brake pedal several times to exhaust reserve vacuum, holds firm pressure on the pedal, and starts the engine. The pedal drops slightly under the foot. Technician A says this indicates a ruptured booster diaphragm. Technician B says this indicates a leaking vacuum check valve. Who is right?

   • A.Both Technician A and Technician B
   • B.Technician B only
   • C.Technician A only
   • D.Neither Technician A nor Technician B✓ Answer

   With the engine off and reserve vacuum used up, the pedal is high and hard. Starting the engine puts vacuum on one side of the booster diaphragm while atmospheric pressure on the other side pushes the pushrod, so a slight pedal drop is exactly what a working booster does. Neither technician has described a fault.

   Source: ASE Automobile Study Guide, Brakes (A5) task list - vacuum booster system testingReport a problem with this question

3. 3. A section of steel brake line is badly rusted and is leaking. What is the correct repair?

   • A.Braze the leaking spot closed and coat the repaired area with sealer
   • B.Splice in copper tubing with compression fittings for corrosion resistance
   • C.Replace the section with steel brake tubing using double or ISO flares✓ Answer
   • D.Install soft aluminum tubing single-flared into the original fittings

   Brake hydraulic lines must be steel tubing terminated in double (SAE) or ISO bubble flares, which are formed to seal at brake system pressures and to resist vibration fatigue. Copper and soft aluminum tubing, single flares, compression fittings and brazed patches are not approved for hydraulic brake lines and can burst.

   Source: ASE Automobile Study Guide, Brakes (A5) task list - brake lines, hoses and fittings; standard practice requiring double or ISO flared steel brake tubingReport a problem with this question

4. 4. One front wheel drags and its rotor is very hot after a short drive. When the caliper bleeder screw is opened, fluid spurts out and the wheel then turns freely. What does this indicate?

   • A.The flexible hose to that caliper is restricted and traps pressure✓ Answer
   • B.The caliper piston seal is torn, so the piston cannot retract at all
   • C.The caliper mounting slides are seized and hold the pads on the rotor
   • D.The master cylinder pushrod is long and blocks the compensating port

   A flex hose that has collapsed internally acts as a one-way valve: it passes pressure on apply but will not let it bleed back, so the caliper stays applied and overheats. Fluid spurting from the bleeder proves pressure was trapped between the restriction and the caliper. A master cylinder pushrod fault would drag all four wheels, and seized slides do not trap hydraulic pressure.

   Source: ASE Automobile Study Guide, Brakes (A5) task list - diagnose brake drag and hydraulic restrictionsReport a problem with this question

5. 5. During pressure bleeding of a front-disc, rear-drum system with a combination valve, no fluid will flow from the front bleeders at the applied bleeding pressure. What should the technician do?

   • A.Hold the metering valve open with the proper tool or release button✓ Answer
   • B.Raise bleeder pressure until the proportioning valve opens the front
   • C.Clamp the rear flexible hoses so all pressure reaches the front calipers
   • D.Press the pressure differential switch to recenter its internal piston

   The metering, or hold-off, valve blocks pressure to the front calipers until enough pressure builds to overcome the rear shoe return springs, so both ends apply together. Pressure bleeding is normally done below that hold-off pressure, so the valve must be held open with the manufacturer's tool or its release button before fluid will flow at the front.

   Source: ASE Automobile Study Guide, Brakes (A5) task list - metering (hold-off) valve inspection and system bleedingReport a problem with this question

6. 6. During a hard stop on dry pavement the rear wheels lock before the fronts on a vehicle without ABS. Which condition would most likely cause this?

   • A.A metering valve stuck open, applying the front discs too early
   • B.A failed proportioning valve passing full pressure to the rear circuit✓ Answer
   • C.A pressure differential switch stuck off center toward the rear
   • D.A residual check valve missing from the rear drum brake circuit

   Weight transfers forward during hard braking, so the lightly loaded rear wheels lock first unless rear pressure is limited. The proportioning valve limits rear circuit pressure above a split point; if it fails and passes full pressure, the rear wheels lock early. A metering valve affects the front, and a residual check valve only keeps a few psi in a drum circuit.

   Source: ASE Automobile Study Guide, Brakes (A5) task list - proportioning valve diagnosisReport a problem with this question

7. 7. A residual pressure check valve is used in a drum brake hydraulic circuit. What is its purpose?

   • A.To delay drum apply until the front disc pads have contacted the rotors
   • B.To limit rear circuit pressure so the rear wheels cannot lock up early
   • C.To hold slight pressure so wheel cylinder cup lips stay sealed against air✓ Answer
   • D.To keep the shoes lightly applied so the self-adjusters work in reverse

   A residual pressure check valve keeps a small pressure, roughly 5 to 12 psi, in a drum circuit so the wheel cylinder cup lips stay expanded against the bore and air cannot be drawn past them when the shoes return. It is never used in a disc circuit, where any residual pressure would hold the pads against the rotor and cause drag.

   Source: ASE Automobile Study Guide, Brakes (A5) task list - brake system valves and residual pressure check valve functionReport a problem with this question

8. 8. A vehicle with hydro-boost hydraulic power assist has a hard brake pedal and poor assist. Which check should be made first?

   • A.Test the vacuum check valve at the booster for its ability to hold vacuum
   • B.Inspect the power steering fluid level, belt, and hoses at the pump✓ Answer
   • C.Measure engine manifold vacuum at idle with a gauge at the booster port
   • D.Replace the booster accumulator because it no longer stores any pressure

   Hydro-boost takes its assist from the power steering pump, not from engine vacuum, so a hard pedal points first to power steering fluid level, a slipping or broken belt, restricted hoses, or a worn pump. Vacuum checks belong to a vacuum booster and tell nothing about this design, and parts are not replaced before the basic checks are made.

   Source: ASE Automobile Study Guide, Brakes (A5) task list - hydraulic (hydro-boost) power assist diagnosisReport a problem with this question

9. 9. New rear pads are to be installed on a vehicle whose electric parking brake uses motor-on-caliper actuators. What must be done before the pistons are retracted?

   • A.Release the parking brake switch and compress the pistons with a C-clamp
   • B.Place the calipers in service mode with a scan tool, then retract them✓ Answer
   • C.Back off the cable adjuster at the equalizer until the pistons move freely
   • D.Disconnect the battery so the parking brake motors cannot apply the brakes

   A motor-on-caliper parking brake piston is driven by an internal screw, so the caliper must be commanded into service or maintenance mode with a scan tool and the motor run back before the piston will move. Forcing it straight in with a clamp damages the actuator, and this design has no cable equalizer. The system is re-initialized after the pads are installed.

   Source: ASE Automobile Study Guide, Brakes (A5) task list - electronic parking brake caliper retraction and initializationReport a problem with this question

10. 10. All of the following statements about brake fluid are true EXCEPT:

    • A.Brake fluid must be poured from a sealed container, and used fluid is never reused
    • B.DOT 5 silicone fluid may be added to a DOT 3 system to raise the boiling point✓ Answer
    • C.DOT 3 and DOT 4 glycol fluids are hygroscopic, and absorbed water lowers the boiling point
    • D.DOT 4 glycol fluid has a higher specified dry boiling point than DOT 3 fluid does

    DOT 5 is silicone based and is not miscible with the glycol based DOT 3, DOT 4 and DOT 5.1 fluids; mixing them causes sludging, poor lubrication of seals and a spongy pedal, and DOT 5 is also unsuitable for most antilock systems. The other three statements are correct.

    Source: FMVSS No. 116, Motor Vehicle Brake Fluids (DOT 3, DOT 4, DOT 5 and DOT 5.1 designations)Report a problem with this question

11. 11. A vehicle with rear duo-servo drum brakes has a low brake pedal that comes up when pumped, and the pedal improves after several hard stops in reverse. What is the most likely cause?

    • A.Inoperative self-adjusters leaving excessive lining-to-drum clearance✓ Answer
    • B.An internally leaking master cylinder that bypasses on every apply
    • C.Grease-soaked linings that cannot generate normal servo action
    • D.Weak shoe return springs that let the linings stay near the drums

    Excess lining-to-drum clearance means the first pedal stroke is used up taking up clearance, and each following stroke has less to take up, so the pedal pumps up. Duo-servo self-adjusters are operated by reverse stops, so a pedal that improves after backing up points at the adjuster mechanism rather than at the hydraulic system.

    Source: ASE Automobile Study Guide, Brakes (A5) task list - drum brake self-adjuster diagnosisReport a problem with this question

12. 12. All of the following are correct drum brake service practices EXCEPT:

    • A.Lubricating the backing plate shoe pads with high-temperature brake lubricant
    • B.Torquing the lug nuts in a star pattern with a torque wrench on reassembly
    • C.Wet-cleaning the assembly or using an enclosed HEPA vacuum before service
    • D.Blowing the assembly clean with shop compressed air before disassembly✓ Answer

    Compressed air is never used on brake assemblies because it puts respirable brake dust, historically containing asbestos, into the technician's breathing zone; wet cleaning or an enclosed vacuum with a HEPA filter is required instead. The other three practices are correct drum brake service.

    Source: OSHA asbestos standard, automotive brake and clutch repair work appendix (29 CFR 1910.1001)Report a problem with this question

13. 13. A customer reports a brake pedal pulsation with steering wheel shudder that happens only while braking. Which measurement most directly identifies the cause?

    • A.Wheel and tire radial runout measured with a dial indicator on the tread
    • B.Rotor thickness variation measured with a micrometer around the rotor✓ Answer
    • C.Rotor lateral runout measured with a dial indicator on the rotor face
    • D.Rotor thickness compared with the minimum value cast into the rotor hat

    Pulsation felt while braking comes from disc thickness variation: the rotor is thicker in some places than others, so the caliper piston is pushed in and out once per revolution. Thickness variation is measured with a micrometer at several points around the rotor. Lateral runout, read with a dial indicator, creates thickness variation over time but is not the direct measurement, and a front rotor is what shows up as steering wheel shudder.

    Source: ASE Automobile Study Guide, Brakes (A5) task list - measure rotor thickness variation and diagnose pulsationReport a problem with this question

14. 14. After machining, a rotor measures less than the minimum thickness cast into it. What should the technician do?

    • A.Replace the rotor, because the cast figure is the discard specification✓ Answer
    • B.Install it with new pads, since machining always removes some material
    • C.Reuse it if runout and thickness variation are within specification
    • D.Machine the opposite rotor to the same thickness so the pair matches

    The thickness cast or stamped into the rotor is the discard specification, the minimum allowed in service, not a machining target. A rotor at or below it has too little mass to absorb and shed heat, so it is prone to fade, distortion and cracking and must be replaced rather than reused or matched to the other side.

    Source: ASE Automobile Study Guide, Brakes (A5) task list - rotor minimum (discard) thickness specificationReport a problem with this question

15. 15. A single-piston floating caliper is found with the inboard pad worn much more than the outboard pad. Technician A says binding caliper slides or pins can cause this. Technician B says excessive rotor lateral runout is the usual cause. Who is right?

    • A.Technician B only
    • B.Neither Technician A nor Technician B
    • C.Technician A only✓ Answer
    • D.Both Technician A and Technician B

    On a floating caliper only the inboard pad is pushed directly by the piston; the outboard pad is applied as the caliper housing slides on its pins. If the slides bind, the housing cannot follow, so the inboard pad does nearly all the work and wears much faster. Excessive lateral runout wears both pads and shows up as pulsation, so Technician A only is correct.

    Source: ASE Automobile Study Guide, Brakes (A5) task list - floating caliper inspection and uneven pad wear diagnosisReport a problem with this question

16. 16. A growling noise rises in pitch with vehicle speed, does not change when the brakes are applied, and gets louder when the vehicle is steered to one side. What is the most likely cause?

    • A.A warped rotor knocking the pads back at road speed
    • B.A dragging parking brake shoe rubbing inside the drum
    • C.A pad wear indicator contacting the rotor friction surface
    • D.A worn wheel bearing loaded by cornering side thrust✓ Answer

    Bearing noise is tied to wheel rotation, so it tracks vehicle speed rather than engine speed and does not change when the brakes are applied. Cornering shifts vehicle weight to the outside wheels, so a growl that gets louder while turning one way identifies the loaded bearing as the source.

    Source: ASE Automobile Study Guide, Brakes (A5) task list - wheel bearing noise diagnosisReport a problem with this question

17. 17. On the first hard stop on a gravel road, the driver feels the brake pedal pulse and hears rapid clicking and a motor running under the hood. The amber ABS lamp stays off. What does this indicate?

    • A.A faulty hydraulic control unit venting pressure back to the reservoir
    • B.Normal ABS cycling as the module modulates pressure to prevent lockup✓ Answer
    • C.Air in the ABS modulator that must be removed with an automated bleed
    • D.A wheel speed sensor signal dropout that causes false ABS activation

    Rapid pedal pulsation with clicking solenoids and a running pump motor during a stop on a low-traction surface is the antilock system releasing and reapplying pressure exactly as designed. With no stored fault the amber lamp stays off, which confirms normal operation rather than a defect.

    Source: ASE Automobile Study Guide, Brakes (A5) task list - identify normal antilock brake system operationReport a problem with this question

18. 18. Which statement correctly describes an active (Hall-effect or magnetoresistive) wheel speed sensor?

    • A.It stops producing a usable signal below a few miles per hour of speed
    • B.It is powered by the module and outputs a square wave to near zero mph✓ Answer
    • C.It is checked for winding resistance across its terminals with an ohmmeter
    • D.It generates its own AC voltage whose amplitude rises with wheel speed

    An active sensor is supplied voltage by the control module, commonly in the range of about 8 to 12 V, and returns a digital square wave whose frequency tracks wheel speed, so it stays accurate almost to a standstill. The passive variable reluctance sensor is the type that generates its own AC signal and is tested for coil resistance.

    Source: ASE Automobile Study Guide, Brakes (A5) task list - wheel speed sensor testing, active and passive typesReport a problem with this question

19. 19. The amber ABS warning lamp is on steadily, the red BRAKE lamp is off, and the pedal feels normal with good stopping power. What should the driver be told?

    • A.The lamp is only a reminder that fluid has reached the add mark
    • B.Antilock control is still active and the lamp shows a bulb fault
    • C.Base hydraulic braking still works, but antilock control is disabled✓ Answer
    • D.The vehicle should not be driven because hydraulic braking failed

    The amber lamp means a stored fault has disabled the antilock function, while the base hydraulic system keeps working normally, which is why the pedal and stopping power feel unchanged. A base system concern such as low fluid, an applied parking brake or a pressure differential is what turns on the red BRAKE lamp instead.

    Source: FMVSS No. 135, Light Vehicle Brake Systems - antilock malfunction indicator requirementReport a problem with this question

20. 20. An alignment and an outer tie rod replacement were completed on a vehicle with electronic stability control, and the stability control lamp is now on steadily. What is required?

    • A.Perform the steering angle sensor zero and the yaw rate sensor learn✓ Answer
    • B.Replace the steering angle sensor because it was disturbed during the work
    • C.Clear the codes and road test, since the lamp self-corrects after driving
    • D.Perform an automated ABS bleed to purge air from the modulator unit

    Changing toe or replacing a steering linkage part moves the steering wheel relative to the road wheels, so the steering angle sensor no longer reports true straight ahead. Stability control compares steering angle with yaw rate, lateral acceleration and wheel speeds, so the sensor must be zeroed and the related values relearned using the manufacturer's procedure.

    Source: ASE Automobile Study Guide, Brakes (A5) task list - steering angle and yaw rate sensor calibration after serviceReport a problem with this question

21. 21. A vehicle has oversized tires installed on one axle only, sets antilock codes, and shows false ABS activation at low speed. Technician A says mismatched tire sizes can produce wheel speed signals the module reads as a fault. Technician B says a tire diameter different from stock can affect antilock, traction control and stability control operation. Who is right?

    • A.Technician A only
    • B.Both Technician A and Technician B✓ Answer
    • C.Neither Technician A nor Technician B
    • D.Technician B only

    Wheel speed is calculated from tone ring pulses on the assumption that all four tires roll at the same rate for a given road speed. A different rolling diameter on one axle creates a permanent speed difference that the module can store as a fault or act on as wheel slip, and the same wheel speed signals feed traction control and stability control, so both technicians are correct.

    Source: ASE Automobile Study Guide, Brakes (A5) task list - brake concerns caused by vehicle modificationsReport a problem with this question

22. 22. A dial indicator is mounted with its tip against the rotor face about a half inch in from the outer edge, and the rotor is turned one full revolution. What is being measured?

    • A.Lateral runout, the side-to-side wobble of the rotor as it turns✓ Answer
    • B.Minimum thickness, compared with the discard value cast in the hat
    • C.Parallelism, meaning the taper of the rotor from the edge inward
    • D.Thickness variation between opposing points of the friction faces

    A dial indicator reading the rotor face through one full rotation shows lateral runout, how far the face moves side to side as the rotor turns. Thickness measurements require a micrometer instead. Excess runout is corrected by cleaning the hub face and indexing the rotor, then rechecking, because runout eventually wears the rotor into thickness variation and pulsation.

    Source: ASE Automobile Study Guide, Brakes (A5) task list - measure rotor lateral runout with a dial indicatorReport a problem with this question

Practice questions written to the ASE Automobile & Light Truck (A-series) task lists and standard automotive service principles. ASE is a mark of the National Institute for Automotive Service Excellence; this site is not affiliated with or endorsed by ASE. Always follow the vehicle manufacturer's service information for specifications and procedures on a real repair. About the ASE tests →