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FREE Ontario Class D/DZ Licence Test 2025 | ON
Based on the 2025 ON CDL manual
Questions: 25
Mistakes allowed: 5
Passing score: 80%
Ensuring the accuracy and quality of our practice tests is paramount. Learn more about our rigorous standards in our Commitment to Accuracy article.
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.
4.78 out of 5 • 9 votes.
Based on 2025 ON commercial driver's license manual
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List of questions (classic view)
- In determining how well your air brake system works, which is NOT a significant factor?
- Which colour is the trailer supply line?
- When is a pre-trip inspection required?
- What gauges should you check after starting your vehicle?
- Why are there two service tanks in a modern air brake system?
- What is the purpose of the National Safety Code?
- What does this sign mean?
- In Canada, how many classes of dangerous goods are there?
- What must you do at a stop sign with a painted stop line?
- When brakes become overheated, they also become
- What does this sign mean?
- Your vehicle is equipped with an air brake system, including a belt-driven air compressor. How do you check for correct belt tension?
- What does this sign mean?
- Before driving down a grade (hill), you should
- What does this sign mean?
- Your vehicle has tandem drive axles and is equipped with an inter-axle differential. You should NOT use it if
- What does this sign mean?
- What is a commercial vehicle's danger zone?
- This sign indicates that you may park for one hour
- What is the first step of the pre-trip inspection?
- In a vehicle equipped with air brakes, the pushrod stroke occurs when compressed air enters the
- What is the Gross Vehicle Weight Rating (GVWR)?
- Driving a commercial vehicle on the road is
- In an air brake system, what does a governor do?
- Where are the air brake chambers located?