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  • Updated for January 2025
  • Based on 2025 CA commercial driver's license manual

Free California CDL Air Brakes Test 2025

This test contains 30 multiple-choice questions that will allow you to become a safer driver today, as you prepare to take the air brakes exam for your CDL license.

The questions is based on real DMV exam questions and information from the California Commercial Driver Handbook. Each question has a hint and explanation. We recommend that you read the explanations, as they will allow you to better understand the material being covered, and pass your exam so that you can drive vehicles with air brakes.

Good luck on your Air Brakes exam, and drive safely!

  • Perfect for first-time and renewal CDL/CLP applicants, and those adding endorsements

What you need to know

9 min to complete
Available in EN and ES
Verified by Steven Litvintchouk, M.S., Chief Educational Researcher, Member of ACES. See our detailed commitment to accuracy and quality in our practice tests.

What to expect on the actual CA DMV exam

25

questions

20

correct answers to pass

80%

passing score

List of questions (classic view)

  1. How would you check your truck's slack adjusters?
  2. How do brakes work on a long, steep downgrade?
  3. Why must you study air brakes in the state of California?
  4. The purpose of a supply pressure gauge is
  5. Why must air tanks be drained?
  6. Which of the following is NOT part of the drum brake?
  7. Which conditions are ideal for front wheel brakes?
  8. Which of the following is NOT part of the braking process when driving a tractor-trailer combination vehicle with an anti-lock braking system (ABS)?
  9. How can you tell if your vehicle is equipped with an anti-lock braking system (ABS)?
  10. Which vehicles must have low air pressure warning signals?
  11. What is the best way to test if your vehicle's spring brakes come on automatically?
  12. Spring brakes are
  13. Which of the following is true about a dual air brake system?
  14. Slack adjusters are
  15. An anti-lock braking system (ABS)
  16. Which of the following is NOT part of the air brake system?
  17. Which of the following will be true about your brake function if your ABS fails?
  18. The tractor protection valve
  19. When should you use the parking brake?
  20. At what measurement is the safety valve USUALLY set to open?
  21. What is the best way to test your vehicle's low air pressure warning signal?
  22. When should you drain your air tanks?
  23. Which of the following can cause brakes to fail or fade?
  24. The maximum leakage rates per minute after the initial pressure drop are
  25. Which of the following should you do before leaving your vehicle unattended?
  26. The low air pressure warning signal will come on before the pressure in the air tanks falls below
  27. A low pressure warning signal is required on
  28. All vehicles equipped with air brakes have
  29. With air brake-equipped vehicles, the parking brakes should be used
  30. The use of air brakes on a downgrade is only a supplement to the
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