2
ASE T4 brakes Exam with accurate detailed answers
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The low air pressure indicator light and buzzer stay on with the air pressure gauges
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showing 100 psi. Which of these could be the cause? || || || || || || || || ||
(A) A failed double check valve
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(B) A leaking spring brake chamber
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(C) A leaking parking brake control valve
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(D) A failed low air pressure sensor
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Explanation: The gauge reading of 100 psi indicates pressure well above the low-pressure|| || || || || || || || || || || || ||
sensor threshold. As a result, options A, B, and C will not cause the light and buzzer to stay
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ON. The answer is D.
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Which of these could cause the tractor system air pressure to drop to zero psi after a trailer
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emergency line breaks? || ||
(A) A saturated air drier
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(B) A failed tractor protection valve
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(C) A brake application valve not exhausting
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(D) A failed trailer service control valve
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Explanation: A failed tractor protection valve will cause air pressure in the tractor braking
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system to escape after a trailer air line failure. Options A, C, and D will not cause the tractor
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system air pressure to drop to zero psi. The answer is B.
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After the air drier purges, the primary air pressure gauge reads 120 psi and the secondary
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gauge reads 90 psi. No leaks in the system are observed. Which of these could be the cause?
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(A) A stuck-open air compressor unloader valve
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, 2
(B) A failed air compressor governor
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(C) A failed gauge in the instrument cluster
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(D) A seized parking brake control valve
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Explanation: The primary and secondary pressure gauges should read the same pressures in
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a normalized state. Options A and B will affect both gauges equally. Option D will have no
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effect on the system pressures. The answer is C.
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A truck that has the air compressor inlet connected to the engine air cleaner housing has
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excessive oil in the air brake system. This could be caused by:
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(A) worn air compressor piston rings.
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(B) a restricted turbocharger oil supply line.
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(C) misadjusted brake chamber stroke.
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(D) a leaking air control line
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Explanation: Worn compressor piston rings can allow oil to enter the pumping chamber
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during the intake stroke. This will cause excessive oil to be present in the air brake system.
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Options B, C, and D will not cause oil to be present in the air brake system. The answer is
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A.
With the truck running and the air compressor pumping continuously, the air system will
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not build air pressure. Which of these could be the cause?
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(A) A stuck-open unloader piston
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(B) A stuck-open double check valve
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(C) A leaking air governor mounting gasket
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(D)A leaking air compressor inlet hose
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Explanation: A stuck-open unloader piston will allow air in the compressor to circulate
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between the cylinders, preventing additional pressure from building in the system. Options
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B, C, and D will not prevent the system from building pressure. The answer is A.
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ASE T4 brakes Exam with accurate detailed answers
|| || || || || || ||
The low air pressure indicator light and buzzer stay on with the air pressure gauges
|| || || || || || || || || || || || || || ||
showing 100 psi. Which of these could be the cause? || || || || || || || || ||
(A) A failed double check valve
|| || || || ||
(B) A leaking spring brake chamber
|| || || || ||
(C) A leaking parking brake control valve
|| || || || || ||
(D) A failed low air pressure sensor
|| || || || || ||
Explanation: The gauge reading of 100 psi indicates pressure well above the low-pressure|| || || || || || || || || || || || ||
sensor threshold. As a result, options A, B, and C will not cause the light and buzzer to stay
|| || || || || || || || || || || || || || || || || || ||
ON. The answer is D.
|| || || ||
Which of these could cause the tractor system air pressure to drop to zero psi after a trailer
|| || || || || || || || || || || || || || || || || ||
emergency line breaks? || ||
(A) A saturated air drier
|| || || ||
(B) A failed tractor protection valve
|| || || || ||
(C) A brake application valve not exhausting
|| || || || || ||
(D) A failed trailer service control valve
|| || || || || ||
Explanation: A failed tractor protection valve will cause air pressure in the tractor braking
|| || || || || || || || || || || || || ||
system to escape after a trailer air line failure. Options A, C, and D will not cause the tractor
|| || || || || || || || || || || || || || || || || ||
system air pressure to drop to zero psi. The answer is B.
|| || || || || || || || || || || ||
After the air drier purges, the primary air pressure gauge reads 120 psi and the secondary
|| || || || || || || || || || || || || || || ||
gauge reads 90 psi. No leaks in the system are observed. Which of these could be the cause?
|| || || || || || || || || || || || || || || || ||
(A) A stuck-open air compressor unloader valve
|| || || || || ||
, 2
(B) A failed air compressor governor
|| || || || ||
(C) A failed gauge in the instrument cluster
|| || || || || || ||
(D) A seized parking brake control valve
|| || || || || ||
Explanation: The primary and secondary pressure gauges should read the same pressures in
|| || || || || || || || || || || ||
a normalized state. Options A and B will affect both gauges equally. Option D will have no
|| || || || || || || || || || || || || || || || || ||
effect on the system pressures. The answer is C.
|| || || || || || || ||
A truck that has the air compressor inlet connected to the engine air cleaner housing has
|| || || || || || || || || || || || || || || ||
excessive oil in the air brake system. This could be caused by:
|| || || || || || || || || || ||
(A) worn air compressor piston rings.
|| || || || ||
(B) a restricted turbocharger oil supply line.
|| || || || || ||
(C) misadjusted brake chamber stroke.
|| || || ||
(D) a leaking air control line
|| || || || ||
Explanation: Worn compressor piston rings can allow oil to enter the pumping chamber
|| || || || || || || || || || || || ||
during the intake stroke. This will cause excessive oil to be present in the air brake system.
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Options B, C, and D will not cause oil to be present in the air brake system. The answer is
|| || || || || || || || || || || || || || || || || || || ||
A.
With the truck running and the air compressor pumping continuously, the air system will
|| || || || || || || || || || || || || ||
not build air pressure. Which of these could be the cause?
|| || || || || || || || || ||
(A) A stuck-open unloader piston
|| || || ||
(B) A stuck-open double check valve
|| || || || ||
(C) A leaking air governor mounting gasket
|| || || || || ||
(D)A leaking air compressor inlet hose
|| || || || ||
Explanation: A stuck-open unloader piston will allow air in the compressor to circulate
|| || || || || || || || || || || || ||
between the cylinders, preventing additional pressure from building in the system. Options
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B, C, and D will not prevent the system from building pressure. The answer is A.
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