AL DMV Commercial Driver's License 3 — Questions and Answers
Question 1: When checking your mirrors while driving a large truck, how often should you glance at them?
- Only when changing lanes
- Regularly as part of your scanning routine (Correct answer)
- Every 30 seconds exactly
- Only in heavy traffic
Correct answer: Regularly as part of your scanning routine
Mirrors should be checked regularly as part of a constant scanning routine, not just for lane changes or turns.
Question 2: What is the proper way to test your service brakes after starting to drive?
- Slam the brakes at 30 mph
- Push the brake pedal firmly at about 5 mph (Correct answer)
- Pump the pedal three times while parked
- Apply the parking brake while moving fast
Correct answer: Push the brake pedal firmly at about 5 mph
Test service brakes by driving forward at about 5 mph and pressing the pedal firmly to check for pulling or delay.
Question 3: A driver operating a CMV in Alabama is caught texting while driving. What can happen after a second conviction within three years?
- A written warning only
- A 60-day CDL disqualification (Correct answer)
- A lifetime CDL ban
- Nothing if driving intrastate
Correct answer: A 60-day CDL disqualification
A second conviction for a serious traffic violation like texting within three years brings a 60-day disqualification.
Question 4: When driving down a long, steep downgrade, which braking technique is recommended?
- Ride the brakes lightly the entire way down
- Use engine braking and apply brakes firmly to slow 5 mph below your safe speed, then release (Correct answer)
- Coast in neutral to reduce brake wear
- Apply the parking brake intermittently
Correct answer: Use engine braking and apply brakes firmly to slow 5 mph below your safe speed, then release
Use a low gear with engine braking and the snub technique, braking to 5 mph below your safe speed then releasing.
Question 5: What does it mean if your vehicle's low air pressure warning signal activates?
- The tires are underinflated
- The air brake system pressure has dropped to a dangerous level (Correct answer)
- The air conditioning has failed
- The trailer is overloaded
Correct answer: The air brake system pressure has dropped to a dangerous level
The low air warning activates when air brake system pressure falls below about 60 psi, requiring you to stop safely at once.
Question 6: How much space should you keep in front of you for every 10 feet of vehicle length when traveling below 40 mph?
- Half a second
- One second (Correct answer)
- Two seconds
- Three seconds
Correct answer: One second
Allow at least one second of following distance per 10 feet of vehicle length at speeds under 40 mph, adding one more second above 40 mph.
Question 7: Which of the following is true about using a CB radio or mobile phone while driving a CMV?
- Hands-free mobile phone use is permitted (Correct answer)
- All radio communication is banned
- Texting is allowed at stop lights
- Holding a phone is fine under 25 mph
Correct answer: Hands-free mobile phone use is permitted
Federal rules allow hands-free phone use but prohibit holding, dialing, or texting on a mobile device while driving a CMV.
AL DMV Commercial Driver's License 3
When checking your mirrors while driving a large truck, how often should you glance at them?