T4 ASE BRAKES (MEDIUM/HEAVY
DUTY BRAKES) EXAM QUESTIONS
AND ANSWERS WITH COMPLETE
SOLUTIONS
On a car with disc/drum brakes, the front brakes grab quickly when light pedal pressure is applied. This
problem could be caused by a bad:
A. Proportioning valve
B. Pressure safety switch
C. Metering valve
D. Residual check valve - ANSWER - The correct answer is C. The metering valve delays the flow of brake
fluid to the front calipers until the pressure in the system rises to a point where the wheel cylinder can
overcome the tension of the brake shoe returning spring. The purpose is to have both front and rear
brakes apply simultaneously. This prevents the front brakes from locking up during light brake
applications.
The driver of a vehicle with power disc/drum brakes says that the brake pedal moved slowly to the floor
while maintaining pedal pressure at a stoplight. What could cause this problem?
A. Leaking primary piston cup in master cylinder
B. Leaking power brake booster
C. Leaking residual check valve in master cylinder
D. Internal leak in the combination valve - ANSWER - The correct answer is A. if the primary piston cup in
the master cylinder is leaking, pressure will not build up ahead of the primary piston to increase
pressure to the rear brakes. The piston will then move forward until the spring is compressed enough to
move the secondary piston. Consequently, this internal leak will cause the brake pedal to slowly drop to
the floor.
What is the purpose of the master cylinder residual check valve(s) on vehicles equipped with drum
brakes?
A. Allowed the driver to pump up the brakes
,B. Prevents air from entering the hydraulic system
C. Prevents wheel lockup by reducing the hydraulic pressure
D. Reduces pedal pulsation by controlling hydraulic pressure - ANSWER - The correct answer is B.
Residual check valve(s) are used on drum brakes to keep residual low pressure (slight static pressure) in
the brake system at all times even when the brake pedal is released. This pressure (5-20 psi) keeps the
lips of the wheel cylinder piston cups tight against the cylinder walls to prevent air from entering the
system when at rest (brakes released).
A technician has just overhauled the front brakes on a vehicle with front disc and rear drum brakes.
However, when he attaches a pressure bleeder (pressurized to about 25 psi) to the master cylinder, he
cannot get any fluid to come out of the disc brake caliper bleeder screws. Which of the following is
MOST LIKELY the cause?
A. Bad proportioning valve
B. Bad pressure differential valve
C. proportioning valve release button not activated
D. Metering valve release button not activated - ANSWER - The correct answer is D. A metering valve
requires a minimum pressure (typically 75-125 psi) to open. At this point pressurized fluid flows to the
front calipers. Since the bleeder tank is only pressurized to 25 psi, fluid pressure is too low to open the
metering valve during this procedure, Therefore, when you use a pressure bleeder on a system with a
metering valve, you must manually keep the valve open by either pushing the button in the end of the
valve, or pulling the stem outward on the end of the valve.
On a vehicle with single piston floating caliper front disc brakes, the brake pads on the left side of the
vehicle are almost completely worn while the right side is almost new. Tech A says that too much rotor
runout could be the cause. Tech B says that a binding caliper piston could be the cause. Who is right?
A. Technician A only
B. Technician B only
C. Both A and B
D. Neither A or B - ANSWER - The correct answer is B. Excessive rotor runout would cause a pulsating
brake pedal, but not uneven side-to-side pad wear. A frozen caliper piston on the other hand, will keep
both inner and outer brake pads equally applied against the rotor even when the brake pedal is
released. This constant friction will cause rapid pad wear in the affected caliper as well as the front-end
pull
A hydraulic brake line is leaking. Which of the following is the correct repair procedure?
, A. Cut out the bad section and replace with new steel tubing using compression fittings.
B. Replace the leaking line with double-flared, seamless copper tubing.
C. Cut out the bad section and replaced with single-flared steel tubing using flare nuts and unions.
D. Replace the leaking line with double-flared steel tubing. - ANSWER - The correct answer is D. Steel
tubing of the same size, type, and length with double flared ends must be used when replacing a
traditional SAE double inverted flair style hydraulic brake line.
Which of the following problems would be caused by using a residual check valve in a disc brake master
cylinder?
A. Reduced brake pedal travel
B. Reduced brake system pressure
C. Increased brake pad wear
D. Increased rotor runout. - ANSWER - The correct answer is C. If a residual check valve was installed in a
disc brake master cylinder, it would cause increased brake pad wear since the residual brake pressure
would cause the caliper pistons to keep the pads applied even when the brake pedal is released.
A customer complains that their vehicle pulls to the right when the brakes are applied. Technician A says
a restricted brake line to the left caliper can cause this problem. Technician B says a malfunctioning
proportioning valve is probably the cause. Who is right?
A. Technician A only
B. Technician B only
C. Both A and B
D. Neither A or B - ANSWER - The correct answer is A. A restriction in the brake line will cause a drop in
fluid pressure to the affected caliper. This will cause the caliper to be unable to exert the same force
against the pads as the unrestricted side. because of this, the vehicle will pull to the side where the
pressure is highest and brake force is greatest. In this case, that would be the right side.
With foot pressure applied, the brake pedal on a vehicle with vacuum assisted power brakes moves
down slightly when the engine is started. Tech A says that this condition can be caused by a leaking
power brake booster diaphragm. Tech B says that the cause could be a faulty power brake booster check
valve. Who is right?
A. Technician A only
B. Technician B only
DUTY BRAKES) EXAM QUESTIONS
AND ANSWERS WITH COMPLETE
SOLUTIONS
On a car with disc/drum brakes, the front brakes grab quickly when light pedal pressure is applied. This
problem could be caused by a bad:
A. Proportioning valve
B. Pressure safety switch
C. Metering valve
D. Residual check valve - ANSWER - The correct answer is C. The metering valve delays the flow of brake
fluid to the front calipers until the pressure in the system rises to a point where the wheel cylinder can
overcome the tension of the brake shoe returning spring. The purpose is to have both front and rear
brakes apply simultaneously. This prevents the front brakes from locking up during light brake
applications.
The driver of a vehicle with power disc/drum brakes says that the brake pedal moved slowly to the floor
while maintaining pedal pressure at a stoplight. What could cause this problem?
A. Leaking primary piston cup in master cylinder
B. Leaking power brake booster
C. Leaking residual check valve in master cylinder
D. Internal leak in the combination valve - ANSWER - The correct answer is A. if the primary piston cup in
the master cylinder is leaking, pressure will not build up ahead of the primary piston to increase
pressure to the rear brakes. The piston will then move forward until the spring is compressed enough to
move the secondary piston. Consequently, this internal leak will cause the brake pedal to slowly drop to
the floor.
What is the purpose of the master cylinder residual check valve(s) on vehicles equipped with drum
brakes?
A. Allowed the driver to pump up the brakes
,B. Prevents air from entering the hydraulic system
C. Prevents wheel lockup by reducing the hydraulic pressure
D. Reduces pedal pulsation by controlling hydraulic pressure - ANSWER - The correct answer is B.
Residual check valve(s) are used on drum brakes to keep residual low pressure (slight static pressure) in
the brake system at all times even when the brake pedal is released. This pressure (5-20 psi) keeps the
lips of the wheel cylinder piston cups tight against the cylinder walls to prevent air from entering the
system when at rest (brakes released).
A technician has just overhauled the front brakes on a vehicle with front disc and rear drum brakes.
However, when he attaches a pressure bleeder (pressurized to about 25 psi) to the master cylinder, he
cannot get any fluid to come out of the disc brake caliper bleeder screws. Which of the following is
MOST LIKELY the cause?
A. Bad proportioning valve
B. Bad pressure differential valve
C. proportioning valve release button not activated
D. Metering valve release button not activated - ANSWER - The correct answer is D. A metering valve
requires a minimum pressure (typically 75-125 psi) to open. At this point pressurized fluid flows to the
front calipers. Since the bleeder tank is only pressurized to 25 psi, fluid pressure is too low to open the
metering valve during this procedure, Therefore, when you use a pressure bleeder on a system with a
metering valve, you must manually keep the valve open by either pushing the button in the end of the
valve, or pulling the stem outward on the end of the valve.
On a vehicle with single piston floating caliper front disc brakes, the brake pads on the left side of the
vehicle are almost completely worn while the right side is almost new. Tech A says that too much rotor
runout could be the cause. Tech B says that a binding caliper piston could be the cause. Who is right?
A. Technician A only
B. Technician B only
C. Both A and B
D. Neither A or B - ANSWER - The correct answer is B. Excessive rotor runout would cause a pulsating
brake pedal, but not uneven side-to-side pad wear. A frozen caliper piston on the other hand, will keep
both inner and outer brake pads equally applied against the rotor even when the brake pedal is
released. This constant friction will cause rapid pad wear in the affected caliper as well as the front-end
pull
A hydraulic brake line is leaking. Which of the following is the correct repair procedure?
, A. Cut out the bad section and replace with new steel tubing using compression fittings.
B. Replace the leaking line with double-flared, seamless copper tubing.
C. Cut out the bad section and replaced with single-flared steel tubing using flare nuts and unions.
D. Replace the leaking line with double-flared steel tubing. - ANSWER - The correct answer is D. Steel
tubing of the same size, type, and length with double flared ends must be used when replacing a
traditional SAE double inverted flair style hydraulic brake line.
Which of the following problems would be caused by using a residual check valve in a disc brake master
cylinder?
A. Reduced brake pedal travel
B. Reduced brake system pressure
C. Increased brake pad wear
D. Increased rotor runout. - ANSWER - The correct answer is C. If a residual check valve was installed in a
disc brake master cylinder, it would cause increased brake pad wear since the residual brake pressure
would cause the caliper pistons to keep the pads applied even when the brake pedal is released.
A customer complains that their vehicle pulls to the right when the brakes are applied. Technician A says
a restricted brake line to the left caliper can cause this problem. Technician B says a malfunctioning
proportioning valve is probably the cause. Who is right?
A. Technician A only
B. Technician B only
C. Both A and B
D. Neither A or B - ANSWER - The correct answer is A. A restriction in the brake line will cause a drop in
fluid pressure to the affected caliper. This will cause the caliper to be unable to exert the same force
against the pads as the unrestricted side. because of this, the vehicle will pull to the side where the
pressure is highest and brake force is greatest. In this case, that would be the right side.
With foot pressure applied, the brake pedal on a vehicle with vacuum assisted power brakes moves
down slightly when the engine is started. Tech A says that this condition can be caused by a leaking
power brake booster diaphragm. Tech B says that the cause could be a faulty power brake booster check
valve. Who is right?
A. Technician A only
B. Technician B only
