CDL Commercial Driver’s License Exam
2026/2027 | Complete Exam Questions with
Verified Answers & Detailed Rationales |
General Knowledge
Question 1
As the blood alcohol concentration (BAC) goes up, what happens?
A) The drinker more clearly sees how alcohol is affecting him/her
B) The effects of alcohol decrease
C) Judgment and self-control are affected
D) Vision improves
Answer: C
Rationale: As BAC rises, judgment and self-control are progressively impaired.
Alcohol is a central nervous system depressant that affects cognitive function, reaction
time, and decision-making ability.
Question 2
Implied consent means:
A) It is understood that you may drink alcohol now and consent to be tested for alcohol
then
B) You have given your consent to be tested for alcohol in your blood
C) You have given your consent to inspection of your vehicle for alcohol
D) You consent to have your vehicle searched without a warrant
Answer: B
Rationale: Implied consent laws mean that by operating a commercial vehicle, you
have already consented to chemical testing for alcohol or drugs if lawfully requested.
Question 3
The total weight of the powered unit, the trailer, and the cargo is called:
A) Gross vehicle weight
B) Gross combination weight
C) Gross axle weight
pg. 1
,D) Gross trailer weight
Answer: B
Rationale: Gross combination weight (GCW) is the total weight of the powered unit
(tractor) plus the trailer(s) and cargo combined.
Question 4
If you do not have a CB radio, what is the 1st thing you should do at an accident scene?
A) Protect the area
B) Notify authorities
C) Care for the injured
D) Move vehicles out of the way
Answer: A
Rationale: The first priority is to protect the area by setting up warning devices to
prevent further accidents. Safety of the scene comes before other actions.
Question 5
Which of these is true about mirror adjustment?
A) You should adjust your mirrors prior to starting a trip
B) You can adjust your mirrors while driving
C) Mirrors should be adjusted after starting the trip
D) Mirrors do not need adjustment
Answer: A
Rationale: Mirrors must be adjusted before starting a trip to ensure proper visibility.
Adjusting while driving is dangerous and prohibited.
Question 6
Brake fade:
A) Can be caused by the brakes getting very hot
B) Can be corrected by letting up on the brakes for 1 or 2 seconds and then reapplying
C) Is caused by cold brakes
D) Only occurs on wet roads
Answer: A
Rationale: Brake fade occurs when brakes get very hot, reducing their effectiveness.
Repeated hard braking on downgrades causes heat buildup.
pg. 2
,Question 7
On which fires can water be used?
A) Electrical
B) Gasoline
C) Tires
D) Oil fires
Answer: C
Rationale: Water can be used on tire fires. Water should NEVER be used on electrical
fires (shock hazard) or gasoline/oil fires (spreads the fire).
Question 8
Which of these statements about engine overheating is true?
A) You should never shut off an overheated engine until it has cooled
B) You should never remove the radiator cap on a pressurized system until it has cooled
C) Antifreeze is not needed when the weather is warm
D) You should add cold water immediately
Answer: B
Rationale: Removing the radiator cap from a hot pressurized system can cause violent
release of boiling coolant and steam, causing severe burns. Always let the engine cool
first.
Question 9
Which of these is NOT a danger of rough acceleration?
A) Tire damage
B) Mechanical damage
C) Damage to the coupling
D) Increased fuel efficiency
Answer: A
Rationale: Rough acceleration can cause mechanical damage and damage to the
coupling. Tire damage is not typically caused by rough acceleration.
Question 10
Which of these is true about the use of a heater?
A) When driving in winter weather, you should check that the heater is working properly
B) You must have at least 1 extra heater when driving in winter weather
C) Heaters are optional equipment
pg. 3
, D) Heaters do not need to be checked before winter trips
Answer: A
Rationale: A working heater is essential for winter driving to keep the windshield clear
and driver comfortable. It should be checked before winter trips.
Question 11
What is the proper way to hold the steering wheel?
A) With both hands close together, at the top of the wheel
B) With both hands close together, at the bottom of the wheel
C) With both hands firmly, on opposite sides of the wheel
D) With one hand on top and one on bottom
Answer: C
Rationale: Proper steering wheel grip is with both hands firmly on opposite sides of
the wheel (9 and 3 o'clock positions) for maximum control.
Question 12
If you have a heavy load that is slowing you down on an upgrade, you should:
A) Shift into a lower gear
B) Exit the road until traffic is lighter
C) Drive on the shoulder so others can pass easily
D) Maintain your current gear
Answer: A
Rationale: When climbing a grade with a heavy load, downshift to a lower gear before
you lose too much speed to maintain momentum and engine power.
Question 13
Which of these is NOT a danger when an automatic transmission is forced into a low
gear at high speeds?
A) Damage to the transmission
B) Loss of engine braking effect
C) Loss of steering control
D) Transmission overheating
Answer: C
Rationale: Loss of steering control is NOT a danger of forced downshifting. However,
damage to the transmission and loss of engine braking are real dangers.
pg. 4
2026/2027 | Complete Exam Questions with
Verified Answers & Detailed Rationales |
General Knowledge
Question 1
As the blood alcohol concentration (BAC) goes up, what happens?
A) The drinker more clearly sees how alcohol is affecting him/her
B) The effects of alcohol decrease
C) Judgment and self-control are affected
D) Vision improves
Answer: C
Rationale: As BAC rises, judgment and self-control are progressively impaired.
Alcohol is a central nervous system depressant that affects cognitive function, reaction
time, and decision-making ability.
Question 2
Implied consent means:
A) It is understood that you may drink alcohol now and consent to be tested for alcohol
then
B) You have given your consent to be tested for alcohol in your blood
C) You have given your consent to inspection of your vehicle for alcohol
D) You consent to have your vehicle searched without a warrant
Answer: B
Rationale: Implied consent laws mean that by operating a commercial vehicle, you
have already consented to chemical testing for alcohol or drugs if lawfully requested.
Question 3
The total weight of the powered unit, the trailer, and the cargo is called:
A) Gross vehicle weight
B) Gross combination weight
C) Gross axle weight
pg. 1
,D) Gross trailer weight
Answer: B
Rationale: Gross combination weight (GCW) is the total weight of the powered unit
(tractor) plus the trailer(s) and cargo combined.
Question 4
If you do not have a CB radio, what is the 1st thing you should do at an accident scene?
A) Protect the area
B) Notify authorities
C) Care for the injured
D) Move vehicles out of the way
Answer: A
Rationale: The first priority is to protect the area by setting up warning devices to
prevent further accidents. Safety of the scene comes before other actions.
Question 5
Which of these is true about mirror adjustment?
A) You should adjust your mirrors prior to starting a trip
B) You can adjust your mirrors while driving
C) Mirrors should be adjusted after starting the trip
D) Mirrors do not need adjustment
Answer: A
Rationale: Mirrors must be adjusted before starting a trip to ensure proper visibility.
Adjusting while driving is dangerous and prohibited.
Question 6
Brake fade:
A) Can be caused by the brakes getting very hot
B) Can be corrected by letting up on the brakes for 1 or 2 seconds and then reapplying
C) Is caused by cold brakes
D) Only occurs on wet roads
Answer: A
Rationale: Brake fade occurs when brakes get very hot, reducing their effectiveness.
Repeated hard braking on downgrades causes heat buildup.
pg. 2
,Question 7
On which fires can water be used?
A) Electrical
B) Gasoline
C) Tires
D) Oil fires
Answer: C
Rationale: Water can be used on tire fires. Water should NEVER be used on electrical
fires (shock hazard) or gasoline/oil fires (spreads the fire).
Question 8
Which of these statements about engine overheating is true?
A) You should never shut off an overheated engine until it has cooled
B) You should never remove the radiator cap on a pressurized system until it has cooled
C) Antifreeze is not needed when the weather is warm
D) You should add cold water immediately
Answer: B
Rationale: Removing the radiator cap from a hot pressurized system can cause violent
release of boiling coolant and steam, causing severe burns. Always let the engine cool
first.
Question 9
Which of these is NOT a danger of rough acceleration?
A) Tire damage
B) Mechanical damage
C) Damage to the coupling
D) Increased fuel efficiency
Answer: A
Rationale: Rough acceleration can cause mechanical damage and damage to the
coupling. Tire damage is not typically caused by rough acceleration.
Question 10
Which of these is true about the use of a heater?
A) When driving in winter weather, you should check that the heater is working properly
B) You must have at least 1 extra heater when driving in winter weather
C) Heaters are optional equipment
pg. 3
, D) Heaters do not need to be checked before winter trips
Answer: A
Rationale: A working heater is essential for winter driving to keep the windshield clear
and driver comfortable. It should be checked before winter trips.
Question 11
What is the proper way to hold the steering wheel?
A) With both hands close together, at the top of the wheel
B) With both hands close together, at the bottom of the wheel
C) With both hands firmly, on opposite sides of the wheel
D) With one hand on top and one on bottom
Answer: C
Rationale: Proper steering wheel grip is with both hands firmly on opposite sides of
the wheel (9 and 3 o'clock positions) for maximum control.
Question 12
If you have a heavy load that is slowing you down on an upgrade, you should:
A) Shift into a lower gear
B) Exit the road until traffic is lighter
C) Drive on the shoulder so others can pass easily
D) Maintain your current gear
Answer: A
Rationale: When climbing a grade with a heavy load, downshift to a lower gear before
you lose too much speed to maintain momentum and engine power.
Question 13
Which of these is NOT a danger when an automatic transmission is forced into a low
gear at high speeds?
A) Damage to the transmission
B) Loss of engine braking effect
C) Loss of steering control
D) Transmission overheating
Answer: C
Rationale: Loss of steering control is NOT a danger of forced downshifting. However,
damage to the transmission and loss of engine braking are real dangers.
pg. 4
