DMV Commercial Driver’s License (CDL)
General Knowledge Exam Questions With
Correct Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant Download Pdf
1. What is the primary purpose of pre-trip inspection for a
commercial vehicle?
A. To increase fuel efficiency
B. To check cargo weight distribution
C. To ensure the vehicle is safe to operate
D. To reduce driving time
Answer: C
Rationale: A pre-trip inspection is conducted to identify safety
issues such as brake problems, tire wear, fluid leaks, and lighting
defects before operating the vehicle, ensuring road safety.
2. Which of the following is considered a serious vehicle defect?
A. Slightly dirty windshield
B. Broken turn signal
, C. Low windshield washer fluid
D. Worn seat fabric
Answer: B
Rationale: A broken turn signal directly affects communication
with other drivers and is a safety-critical defect that must be
repaired before operation.
3. What does ABS stand for in a commercial vehicle?
A. Automatic Brake System
B. Air Brake Safety
C. Anti-lock Braking System
D. Auxiliary Brake Support
Answer: C
Rationale: ABS prevents wheel lock-up during braking, helping
maintain steering control during emergency stops.
4. What is the main danger of overloading a truck?
A. Improved braking
B. Increased fuel efficiency
C. Reduced tire wear
D. Longer stopping distance
, Answer: D
Rationale: Overloading increases stopping distance and reduces
braking effectiveness, making the vehicle unsafe.
5. What should you do if your brakes fail while driving?
A. Pump the brake pedal and downshift
B. Turn off the engine immediately
C. Jump out of the vehicle
D. Accelerate to regain control
Answer: A
Rationale: Pumping the brakes and downshifting helps build air
or hydraulic pressure and slow the vehicle safely.
6. What is the safest way to check blind spots?
A. Use mirrors only
B. Look over your shoulder
C. Honk the horn
D. Speed up
Answer: B
Rationale: Looking over your shoulder ensures you can see areas
not covered by mirrors, improving safety when changing lanes.
, 7. What is the purpose of engine braking?
A. Increase speed downhill
B. Reduce wear on brakes
C. Improve fuel economy only
D. Activate cruise control
Answer: B
Rationale: Engine braking helps slow the vehicle without using
service brakes excessively, reducing brake wear and overheating.
8. What is a common cause of brake fade?
A. Cold weather
B. Excessive brake use on long downhill grades
C. Low fuel
D. Overinflated tires
Answer: B
Rationale: Continuous braking on long descents causes heat
buildup, reducing braking efficiency.
9. When should you use hazard lights?
A. When parking illegally
General Knowledge Exam Questions With
Correct Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant Download Pdf
1. What is the primary purpose of pre-trip inspection for a
commercial vehicle?
A. To increase fuel efficiency
B. To check cargo weight distribution
C. To ensure the vehicle is safe to operate
D. To reduce driving time
Answer: C
Rationale: A pre-trip inspection is conducted to identify safety
issues such as brake problems, tire wear, fluid leaks, and lighting
defects before operating the vehicle, ensuring road safety.
2. Which of the following is considered a serious vehicle defect?
A. Slightly dirty windshield
B. Broken turn signal
, C. Low windshield washer fluid
D. Worn seat fabric
Answer: B
Rationale: A broken turn signal directly affects communication
with other drivers and is a safety-critical defect that must be
repaired before operation.
3. What does ABS stand for in a commercial vehicle?
A. Automatic Brake System
B. Air Brake Safety
C. Anti-lock Braking System
D. Auxiliary Brake Support
Answer: C
Rationale: ABS prevents wheel lock-up during braking, helping
maintain steering control during emergency stops.
4. What is the main danger of overloading a truck?
A. Improved braking
B. Increased fuel efficiency
C. Reduced tire wear
D. Longer stopping distance
, Answer: D
Rationale: Overloading increases stopping distance and reduces
braking effectiveness, making the vehicle unsafe.
5. What should you do if your brakes fail while driving?
A. Pump the brake pedal and downshift
B. Turn off the engine immediately
C. Jump out of the vehicle
D. Accelerate to regain control
Answer: A
Rationale: Pumping the brakes and downshifting helps build air
or hydraulic pressure and slow the vehicle safely.
6. What is the safest way to check blind spots?
A. Use mirrors only
B. Look over your shoulder
C. Honk the horn
D. Speed up
Answer: B
Rationale: Looking over your shoulder ensures you can see areas
not covered by mirrors, improving safety when changing lanes.
, 7. What is the purpose of engine braking?
A. Increase speed downhill
B. Reduce wear on brakes
C. Improve fuel economy only
D. Activate cruise control
Answer: B
Rationale: Engine braking helps slow the vehicle without using
service brakes excessively, reducing brake wear and overheating.
8. What is a common cause of brake fade?
A. Cold weather
B. Excessive brake use on long downhill grades
C. Low fuel
D. Overinflated tires
Answer: B
Rationale: Continuous braking on long descents causes heat
buildup, reducing braking efficiency.
9. When should you use hazard lights?
A. When parking illegally
