USPS Exams 943, 944 & 945 – Complete
Practice Exam | Postal Exam Study Guide
with Practice Questions & Answers
Question 1
Which component prevents brake lockup by balancing hydraulic pressure between
front and rear brakes?
A. Metering valve
B. Proportioning valve
C. Residual valve
D. Combination switch
Correct Answer
B. Proportioning valve
Question 2
The purpose of a PCV valve is to:
A. Increase oil pressure
B. Remove crankcase vapors
C. Improve spark timing
D. Increase compression
Correct Answer
B. Remove crankcase vapors
Question 3
Which automatic transmission component directs hydraulic fluid to the various
clutches and bands?
A. Governor
B. Valve body
C. Sprag
D. Torque converter
Correct Answer
B. Valve body
Page 1 of 72
,Question 4
A fusible link is designed to:
A. Increase voltage
B. Protect the electrical system from excessive current
C. Improve starter torque
D. Increase alternator output
Correct Answer
B. Protect the electrical system from excessive current
Question 1: A spongy brake pedal that gradually sinks toward the floor under
steady pressure most commonly indicates which condition?
A. Worn brake pads or shoes
B. Defective brake booster
C. Brakes out of adjustment
D. Air in the hydraulic system
CORRECT ANSWER: D. Air in the hydraulic system
Rationale: Air compresses under pressure, causing the pedal to feel soft or spongy
and to sink as the air is compressed. This is a classic symptom of air trapped in the
brake hydraulic system.
Question 2: During a battery load test, the primary purpose is to determine
whether the battery can deliver which of the following?
A. Sufficient voltage under load to meet minimum standards
B. Maximum amperage without voltage drop
C. Proper charging system output only
D. Cold cranking amperes exclusively
CORRECT ANSWER: A. Sufficient voltage under load to meet minimum
standards
Rationale: A load test applies a controlled load and measures whether the battery
maintains adequate voltage, confirming its ability to perform under real operating
conditions.
Question 3: Which emission control system is common to virtually all modern
cars and light trucks manufactured in the United States?
A. Air Injection Reaction (AIR)
B. Positive Crankcase Ventilation (PCV)
C. Computer Controlled Combustion (CCC)
D. Improved Ignition (II)
Page 2 of 72
,CORRECT ANSWER: B. Positive Crankcase Ventilation (PCV)
Rationale: The PCV system is a fundamental and nearly universal emission control
device that recirculates crankcase vapors into the intake stream for combustion.
Question 4: In an automatic transmission planetary gear set, which of the
following components is a standard part of the assembly?
A. Impeller
B. Modulator
C. Pinion
D. Alternator
CORRECT ANSWER: C. Pinion
Rationale: Planetary gear sets consist of a sun gear, planet pinions (gears), and a
ring gear; the pinion gears are essential elements of the mechanism.
Question 5: During a cylinder leakage test, air escaping from the radiator into
two adjacent cylinders most strongly indicates which problem?
A. Worn cylinder walls
B. Defective cylinder head gasket
C. Leaking piston rings
D. Worn exhaust valves
CORRECT ANSWER: B. Defective cylinder head gasket
Rationale: A blown head gasket between adjacent cylinders allows compressed air
to pass into the cooling system, which then appears as bubbles or air in the
radiator.
Question 6: Which condition is most likely to produce a pulsating brake pedal
during moderate to hard braking?
A. Low brake fluid level
B. Air in the brake lines
C. Out-of-round brake drum or warped rotor
D. Contaminated brake fluid
CORRECT ANSWER: C. Out-of-round brake drum or warped rotor
Rationale: An out-of-round drum or warped rotor causes uneven contact with the
friction material, resulting in a pulsating sensation felt through the pedal.
Question 7: In addition to engine vacuum, which of the following can be used
to open an Exhaust Gas Recirculation (EGR) valve on many systems?
Page 3 of 72
, A. Electricity
B. Hydraulic pressure
C. Manual linkage
D. Compression spring
CORRECT ANSWER: A. Electricity
Rationale: Many modern EGR valves are electronically controlled and opened by an
electric solenoid or stepper motor in addition to or instead of vacuum.
Question 8: A four-gas analyzer shows high hydrocarbon (HC) readings while
the engine misfires only at idle. What is the most probable cause?
A. Leaking intake manifold gasket
B. EGR valve that fails to fully close
C. Secondary ignition wire shorting
D. Partially clogged fuel injector
CORRECT ANSWER: B. EGR valve that fails to fully close
Rationale: An EGR valve stuck open at idle introduces exhaust gas into the intake,
diluting the mixture and causing misfire and elevated HC levels specifically at idle.
Question 9: When performing routine maintenance on a USPS fleet vehicle,
the preferred method for checking engine oil level is to use which procedure?
A. Check with the engine running and hot
B. Check with the engine off after it has been shut down for several minutes on level
ground
C. Check only when the oil is cold
D. Rely solely on the oil pressure warning light
CORRECT ANSWER: B. Check with the engine off after it has been shut down
for several minutes on level ground
Rationale: Allowing the oil to drain back into the pan on level ground provides the
most accurate dipstick reading.
Question 10: A vehicle pulls to one side during braking but tracks straight
when not braking. The most likely cause is which of the following?
A. Incorrect front-end alignment
B. Uneven tire pressure
C. Sticking brake caliper or restricted brake hose on one side
D. Worn suspension bushings
CORRECT ANSWER: C. Sticking brake caliper or restricted brake hose on one
side
Page 4 of 72
Practice Exam | Postal Exam Study Guide
with Practice Questions & Answers
Question 1
Which component prevents brake lockup by balancing hydraulic pressure between
front and rear brakes?
A. Metering valve
B. Proportioning valve
C. Residual valve
D. Combination switch
Correct Answer
B. Proportioning valve
Question 2
The purpose of a PCV valve is to:
A. Increase oil pressure
B. Remove crankcase vapors
C. Improve spark timing
D. Increase compression
Correct Answer
B. Remove crankcase vapors
Question 3
Which automatic transmission component directs hydraulic fluid to the various
clutches and bands?
A. Governor
B. Valve body
C. Sprag
D. Torque converter
Correct Answer
B. Valve body
Page 1 of 72
,Question 4
A fusible link is designed to:
A. Increase voltage
B. Protect the electrical system from excessive current
C. Improve starter torque
D. Increase alternator output
Correct Answer
B. Protect the electrical system from excessive current
Question 1: A spongy brake pedal that gradually sinks toward the floor under
steady pressure most commonly indicates which condition?
A. Worn brake pads or shoes
B. Defective brake booster
C. Brakes out of adjustment
D. Air in the hydraulic system
CORRECT ANSWER: D. Air in the hydraulic system
Rationale: Air compresses under pressure, causing the pedal to feel soft or spongy
and to sink as the air is compressed. This is a classic symptom of air trapped in the
brake hydraulic system.
Question 2: During a battery load test, the primary purpose is to determine
whether the battery can deliver which of the following?
A. Sufficient voltage under load to meet minimum standards
B. Maximum amperage without voltage drop
C. Proper charging system output only
D. Cold cranking amperes exclusively
CORRECT ANSWER: A. Sufficient voltage under load to meet minimum
standards
Rationale: A load test applies a controlled load and measures whether the battery
maintains adequate voltage, confirming its ability to perform under real operating
conditions.
Question 3: Which emission control system is common to virtually all modern
cars and light trucks manufactured in the United States?
A. Air Injection Reaction (AIR)
B. Positive Crankcase Ventilation (PCV)
C. Computer Controlled Combustion (CCC)
D. Improved Ignition (II)
Page 2 of 72
,CORRECT ANSWER: B. Positive Crankcase Ventilation (PCV)
Rationale: The PCV system is a fundamental and nearly universal emission control
device that recirculates crankcase vapors into the intake stream for combustion.
Question 4: In an automatic transmission planetary gear set, which of the
following components is a standard part of the assembly?
A. Impeller
B. Modulator
C. Pinion
D. Alternator
CORRECT ANSWER: C. Pinion
Rationale: Planetary gear sets consist of a sun gear, planet pinions (gears), and a
ring gear; the pinion gears are essential elements of the mechanism.
Question 5: During a cylinder leakage test, air escaping from the radiator into
two adjacent cylinders most strongly indicates which problem?
A. Worn cylinder walls
B. Defective cylinder head gasket
C. Leaking piston rings
D. Worn exhaust valves
CORRECT ANSWER: B. Defective cylinder head gasket
Rationale: A blown head gasket between adjacent cylinders allows compressed air
to pass into the cooling system, which then appears as bubbles or air in the
radiator.
Question 6: Which condition is most likely to produce a pulsating brake pedal
during moderate to hard braking?
A. Low brake fluid level
B. Air in the brake lines
C. Out-of-round brake drum or warped rotor
D. Contaminated brake fluid
CORRECT ANSWER: C. Out-of-round brake drum or warped rotor
Rationale: An out-of-round drum or warped rotor causes uneven contact with the
friction material, resulting in a pulsating sensation felt through the pedal.
Question 7: In addition to engine vacuum, which of the following can be used
to open an Exhaust Gas Recirculation (EGR) valve on many systems?
Page 3 of 72
, A. Electricity
B. Hydraulic pressure
C. Manual linkage
D. Compression spring
CORRECT ANSWER: A. Electricity
Rationale: Many modern EGR valves are electronically controlled and opened by an
electric solenoid or stepper motor in addition to or instead of vacuum.
Question 8: A four-gas analyzer shows high hydrocarbon (HC) readings while
the engine misfires only at idle. What is the most probable cause?
A. Leaking intake manifold gasket
B. EGR valve that fails to fully close
C. Secondary ignition wire shorting
D. Partially clogged fuel injector
CORRECT ANSWER: B. EGR valve that fails to fully close
Rationale: An EGR valve stuck open at idle introduces exhaust gas into the intake,
diluting the mixture and causing misfire and elevated HC levels specifically at idle.
Question 9: When performing routine maintenance on a USPS fleet vehicle,
the preferred method for checking engine oil level is to use which procedure?
A. Check with the engine running and hot
B. Check with the engine off after it has been shut down for several minutes on level
ground
C. Check only when the oil is cold
D. Rely solely on the oil pressure warning light
CORRECT ANSWER: B. Check with the engine off after it has been shut down
for several minutes on level ground
Rationale: Allowing the oil to drain back into the pan on level ground provides the
most accurate dipstick reading.
Question 10: A vehicle pulls to one side during braking but tracks straight
when not braking. The most likely cause is which of the following?
A. Incorrect front-end alignment
B. Uneven tire pressure
C. Sticking brake caliper or restricted brake hose on one side
D. Worn suspension bushings
CORRECT ANSWER: C. Sticking brake caliper or restricted brake hose on one
side
Page 4 of 72
