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4.78 /5
9 votes
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FREE Ontario Class D/DZ Licence Test

  • Perfect for first-time and renewal commercial applicants, and those adding endorsements
  • Based on 2024 ON commercial driver's licence manual
  • Updated for July 2024
Verified by Steven Litvintchouk, M.S., Chief Educational Researcher, Member of ACES. See our detailed commitment to accuracy and quality in our practice tests.
ON commercial driver's licence
4.78 out of 5,
9 votes
What you need to know
The Ontario DZ written test is split into two parts: the Class D license knowledge test, and the Z endorsement test for air brakes. The knowledge test for Class D contains 40 multiple-choice questions about large trucks, and combination vehicles along with trucking regulations. There are two sections: 20 questions focused on road rules specific to heavy trucks and commercial vehicles, and 20 questions on associated road signs and trucking signals. The Z endorsement test, which is separate, tests knowledge of air brakes, how they operate, and how to inspect them. Thus, to acquire a DZ license, both the D license test and Z endorsement test must be passed. If you don't pass either test, you can retake the failed one after repaying the associated fees. Looking for a free Ontario DZ practice test? Take this test below for the D license part, and this free Air Brake practice test for your Z endorsement.
What to expect on the official exam
25

questions

20

correct answers to pass

80

passing score

More resources
  1. General Knowledge 1
  2. General Knowledge 2
  3. General Knowledge 3
  4. General Knowledge 4
  5. General Knowledge 5
  6. General Knowledge 6
  7. General Knowledge 7
  8. Road Signs
  9. Road Signs 2
  10. General Knowledge Marathon
  11. General Knowledge Exam Simulator
  12. Class A Licence Test 1
  13. Class A Licence Test 2
  14. Class A Licence Test 3
  15. Class A Licence Marathon
  16. Class A Licence Exam Simulator
  17. Class B Licence Test 1
  18. Class B Licence Test 2
  19. Class B Licence Test 3
  20. Class B Licence Test 4
  21. Class B Licence Test 5
  22. Class B Licence Test 6
  23. Class B Licence Test 7
  24. Class B Licence Test 8
  25. Class B Licence Test 9
  26. Class B Licence Test 10
  27. Class B Licence Test 11
  28. Class B Licence Marathon
  29. Class B Licence Exam Simulator
  30. Class C Licence Test 1
  31. Class C Licence Test 2
  32. Class C Licence Test 3
  33. Class C Licence Test 4
  34. Class C Licence Test 5
  35. Class C Licence Test 6
  36. Class C Licence Test 7
  37. Class C Licence Test 8
  38. Class C Licence Test 9
  39. Class C Licence Test 10
  40. Class C Licence Test 11
  41. Class C Licence Marathon
  42. Class C Licence Exam Simulator
  43. Class D Licence Test 1 (you are here)
  44. Class D Licence Test 2
  45. Class D Licence Test 3
  46. Class D Licence Marathon
  47. Class D Licence Exam Simulator
  48. Class F Licence Test 1
  49. Class F Licence Test 2
  50. Class F Licence Test 3
  51. Class F Licence Test 4
  52. Class F Licence Test 5
  53. Class F Licence Test 6
  54. Class F Licence Test 7
  55. Class F Licence Test 8
  56. Class F Licence Marathon
  57. Class F Licence Exam Simulator
  58. Air Brake Test 1
  59. Air Brake Test 2
  60. Air Brake Test 3
  61. Air Brake Test 4
  62. Air Brake Test 5
  63. Air Brake Test 6
  64. Air Brake Test 7
  65. Air Brake Test 8
  66. Air Brake Test 9
  67. Air Brake Test 10
  68. Air Brake Test 11
  69. Air Brake Test 12
  70. Air Brake Test 13
  71. Air Brake Test 14
  72. Air Brake Marathon
  73. Air Brake Exam Simulator
  74. AZ Licence Exam Simulator
List of questions (classic view)
  1. In determining how well your air brake system works, which is NOT a significant factor?
  2. Which colour is the trailer supply line?
  3. When is a pre-trip inspection required?
  4. What gauges should you check after starting your vehicle?
  5. Why are there two service tanks in a modern air brake system?
  6. What is the purpose of the National Safety Code?
  7. What does this sign mean?
  8. In Canada, how many classes of dangerous goods are there?
  9. What must you do at a stop sign with a painted stop line?
  10. When brakes become overheated, they also become
  11. What does this sign mean?
  12. Your vehicle is equipped with an air brake system, including a belt-driven air compressor. How do you check for correct belt tension?
  13. What does this sign mean?
  14. Before driving down a grade (hill), you should
  15. What does this sign mean?
  16. Your vehicle has tandem drive axles and is equipped with an inter-axle differential. You should NOT use it if
  17. What does this sign mean?
  18. What is a commercial vehicle's danger zone?
  19. This sign indicates that you may park for one hour
  20. What is the first step of the pre-trip inspection?
  21. In a vehicle equipped with air brakes, the pushrod stroke occurs when compressed air enters the
  22. What is the Gross Vehicle Weight Rating (GVWR)?
  23. Driving a commercial vehicle on the road is
  24. In an air brake system, what does a governor do?
  25. Where are the air brake chambers located?