ASE Practice Test (A5: Brakes)
Which of the following is caused by a power assist brake booster push rod that is too short?
Correct answer: Excessive brake pedal travel
A short push rod length will have to travel farther for contact and result in excessive pedal travel.
Which of the following indicates a spongy brake pedal on a car with 4-wheel disc brakes and a longer than normal travel?
Correct answer: Air in the hydraulic system
Air in the hydraulic system is the only choice that creates a spongy pedal.
A vacuum brake booster is installed on a vehicle. It doesn't have power assist until the engine has been running for a minute, after which it functions normally. What is the most probable cause?
Correct answer: Defective check valve
The defective check valve causes a loss in vacuum when the engine is off. That’s why the power assist begins to function properly after the engine runs. The other three answers wouldn’t cause the same issues.
During braking, the brake pedal on a vehicle with power-assisted disc/drum brakes gently glides to the floor. Which of these possibly be the source of the problem?
Correct answer: An internal master cylinder leak
The cause of the brakes that moves slowly to the floor is an internal master cylinder leak.
What may be the cause of a spongy brake pedal?
Correct answer: Air in hydraulic system
Air causes a gap in the hydraulic fluid flow because the fluid has to compress the air before it can apply the piston. This delay causes the spongy feel. The other choices do not affect this concern.
The ABS (antilock brake system) amber light does not go off after the engine is started. Technician X says a parking brake not fully released could be the cause. Technician Y says when this happens the brakes will operate like a normal non-ABS brake system. Who is right?
Correct answer: Y only If the amber light is on it indicates an ABS fault and the system will revert to regular brake operation without ABS. Technician X is wrong because the parking brake only affects the RED Brake Light not the amber.
Even though all of the adjustments have been done according to the specifications, the brake pedal begins to feel spongy and low. What might be the source of the issue?
Correct answer: Weak hydraulic hose
The weak hydraulic brake hose causes a spongy pedal. The pressure can continue to build and the hose might expand, but not release the pressure to the brake units. Binding pedal linkage would lead to a hard pedal, which is also true for a dented brake line. The plugged compensator port leads to dragging brakes instead.
When light pedal pressure is applied to a vehicle with disc/drum brakes, the front brakes grab quickly. It's possible that this is the result of a failed:
Correct answer: metering valve
The metering valve controls the pressure to the front disc brakes on a combination system and if defective can allow too much pressure causing a lock-up. The other choices will not do this.
Which of the conditions listed below can cause brake pedal fade?
Correct answer: Brake drum machined beyond its limit
The greatest drawback of drum brakes is that they are susceptible to fade. Brake fade is loss of stopping power that occurs when excessive heat reduces friction between brake shoe linings and drum. There are four types of brake fade. Mechanical fade occurs when the brake drum gets so hot it expands away from the brake linings. If the brake drum is machined beyond its limit the contact surface is further from the brake shoes and they move outward to maintain contact with the drum, causing the brake pedal to drop toward the floor as additional brake fluid moves into the hydraulic system. The other 3 choices would not cause brake fade.
The axle grease soaked the rear brake linings, and there's still a lot of lining left on them. What is the proper procedure for servicing these brakes?
Correct answer: Repair leak and replace brake linings
The leak must be repaired before the linings are replaced.
The absence of free play on a vehicle's brake pedal can lead to:
Correct answer: Pressure build-up and dragging brakes
When there’s no free play, the brakes can’t disengage fully. This leads to the brakes dragging. The other situations wouldn’t be caused by the lack of free play.
On a car with single piston floating caliper disc brakes, the disc brake pad between the caliper piston and the rotor is badly worn. The other brake pad is slightly worn. Technician X says excessive rotor run out could be the cause. Technician Y says insufficient clearance between the pads and caliper slider could be the cause. Who is right?
Correct answer: Y only
Insufficient clearance between the pads and caliper slider causes the slider not to move and only applies one brake pad causing only that pad to wear. Technician X is wrong because excessive rotor runout will cause brake pulsations with no effect on wear.
When the front brakes of a car with a drum/disc system are applied lightly, the front brakes lock up. This problem could be caused by a bad:
Correct answer: Metering valve
The metering valve controls the pressure to the front disc brakes on a combination system and if defective can allow too much pressure causing a lock-up. The other choices will not do this.
All of these steps must be completed when removing the master cylinder, except:
Correct answer: Drain the master cylinder
Draining the master cylinder isn’t required. If it needs to be done, the fluid can be removed after the lines are capped. Fluid will not run from the master cylinder while you remove it. Then, it’s easier to empty once it’s out.
When the brakes are applied, the front of a car with a disc/drum system vibrates. Which of these possibly be the source of the problem?
Correct answer: Excessive rotor runout
Excessive rotor runout can be the cause of the vibration that comes from the front of a vehicle.
The race (cup) of a bearing can be dented after it has been shock loaded. What is the type of this sort of bearing failure?
Correct answer: Brinelling
Brinelling is defined as indentations in the race caused by impact loads or vibrations.
Brakes on an older vehicle with a quick take up valve in the master cylinder are being bled. Technician X believes that you must depress the quick take up valve. Technician Y believes that the brakes can’t be bled. Who is correct?
Correct answer: Neither technician
Both of these techs are wrong. The brakes on quick take up systems use the exact bleeding procedure as systems without the valve. You don’t need to do anything different.
After machining, the thickness of a front disc brake rotor is slightly less than the minimum thickness specification. The technician should be able to:
Correct answer: replace the rotor
If the front disc brake rotor is slightly below minimum thickness specification after machining, you have to replace the rotor.
Technician X says a defective wheel or axle bearing can make a growling or rumbling noise. Technician Y says a defective wheel displays looseness or excessive play in the steering wheel especially while driving over rough road surfaces. Who is right?
Correct answer: Both X and Y
Both technicians are correct.
Which of these will be the result of a short power assist brake booster push rod?
Correct answer: Excessive brake pedal travel
The short push rod length has to travel farther to make contact. This leads to excessive pedal travel. The other complaints wouldn’t occur as a result.
A hydraulic brake line has sprung a leak. Which of these repairs is correct?
Correct answer: Replace the leaking line with double-flared steel tubing.
You have to replace the leaking line with double-flared steel tubing when the hydraulic brake line is leaking.
The front wheel bearings are being adjusted. Technician X says you torque the adjusting nut to a specified torque and back off the nut till it lines up with the hole and install the cotter pin. Technician Y says backing off the castle nut will cause the bearing to overheat. Who is right?
Correct answer: X only
You torque an adjusting nut to a specified torque and back off the nut till it lines up with the hole and install the cotter pin. Technician Y is wrong because backing off the castle nut will not cause the bearing to overheat.
When a vehicle's brakes are applied, erratic brake pulling happens. All of these could cause this problem EXCEPT:
Correct answer: High-pressure rubber tubing
Excessive tire pressure isn’t going to cause the erratic pulling. It will lead to increased tire wear. If the vehicle has low or uneven tire pressure, there might be a pull.
After each application, the drag on a vehicle's drum brakes increases until they lock up. For a brief period, bleeding the system restores normal operation; however, drag increases until the brakes lock up again. Which of these possibly be the source of the problem?
Correct answer: A failed master cylinder
A failed master cylinder could be the cause of a vehicle’s drum brakes increases after each application.
The ABS (antilock brake system) and TRACTION OFF indicator lights remain ON with the engine running. Technician X says to check for ABS or TCS (traction control system) diagnostic trouble codes. Technician Y says you can check for ABS or TCS blink codes by connecting two pins of the DLC (Data Link Connector). Who is right?
Correct answer: Both X and Y
Both technicians are correct.
The engine has brake fluid in it, which you notice. This leakage could be caused by:
Correct answer: Defective one-way check valve in booster vacuum hose
A defective hose would not allow the fluid to enter the engine. The PCV valve vents the crankcase of blowby gases and isn’t part of the braking system. The air cleaner also can’t cause a brake fluid leak.
With the brakes applied, the pedal moves down slightly when the engine is started on a vehicle with power brakes. Technician X says that a leaking power brake booster diaphragm could be the cause. Technician Y says that a stuck-closed brake booster vacuum check valve could be the cause. Who is right?
Correct answer: Neither X nor Y
Both technicians are wrong because this is how power brakes are supposed to operate.
A vehicle with disc/drum brakes requires excessive brake pedal effort to stop. The brake pedal is firm when applied. While starting the engine with the brakes applied, the pedal does not go down slightly. Technician X says excessive brake pedal freeplay could be the cause. Technician Y says air trapped in the hydraulic system could be the cause. Who is right?
Correct answer: Neither X nor Y
Both technicians are wrong because the problem is in the power booster. Excessive freeplay delays application and air in the hydraulic system will cause a spongy pedal.
All of these components are included in brake system except:
Correct answer: Double wall copper tubing
Copper tubing should never be used within the brake system. Copper corrodes easily which makes it a poor option. It also expands when subjected to high pressures.
The following would cause a low brake pedal, EXCEPT:
Correct answer: Seized caliper piston
A seized caliper piston could cause the pedal to be high with reduced braking power.