California CDL Combination Test (CA) 2026

4.8 out of 5 (223 votes)
80% Passing score
20 Questions
4 Mistakes allowed
Preparing for your Commercial Driver's License (CDL) Combination Vehicles endorsement is a critical step for any aspiring commercial driver in California. Our first DMV practice test is designed to equip you with the knowledge and skills needed to handle combination vehicles safely and efficiently. With a range of multiple-choice questions, this test delves into crucial areas such as coupling and uncoupling, pre-trip inspections, driving techniques, backing and maneuvering, and air brake systems. Each test features 20 questions, and you'll need to answer at least 16 correctly to pass. This California permit practice test not only prepares you for the written test but also helps you become a safer driver by incorporating real-life driving scenarios into the questions. This practical approach ensures that you are not just memorizing facts but understanding how to apply this knowledge on the road. For instance, you'll learn about the increased stopping distances required for combination vehicles, a vital aspect of maintaining safety due to their greater weight. Visual learning aids are integrated into many of the sample questions, making it easier for visual learners to grasp the material. Images and diagrams accompany the questions, providing a clearer understanding of complex topics. This method helps reinforce learning and retention, ensuring you are well-prepared for both the test and real-world driving. One of the best features of our California CDL practice test is the ability to take it multiple times. This flexibility allows you to practice as much as needed to feel confident and comfortable with the material before moving on to the next set of CDL practice tests. By repeatedly testing your knowledge, you can identify areas where you need improvement and focus your studies accordingly. Our comprehensive California practice permit test is an essential tool for anyone aiming to obtain their CDL Combination Vehicles endorsement. It not only prepares you for the written test but also equips you with the skills needed to navigate the challenges of driving combination vehicles safely. Dive into our DMV practice test today and take the first step towards becoming a proficient and responsible commercial driver in California.
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Sample California Combination Test Questions

Question 1

During a one-minute applied leakage test on a two-vehicle combination with air brakes on both units, what is the maximum permitted pressure loss?

  1. A 2 psi
  2. B 3 psi
  3. C 3½ psi
  4. D 4 psi

Correct answer: D – 4 psi

For a combination of two air-braked vehicles, the maximum applied pressure loss is 4 psi in one minute after the gauge stabilizes. The California handbook lists 3 psi for a single vehicle and 6 psi for a combination of three or more vehicles. Excessive air loss indicates a braking-system problem that must be repaired before operation.

Source: California Commercial Driver Handbook — § 5.3.3, “1. Applied Leakage Test (1-minute hold)”

Question 2

After the kingpin locks into the fifth wheel, how should you test the coupling’s security?

  1. A Accelerate rapidly with the trailer brakes released
  2. B Make a sharp turn while watching the trailer
  3. C Pull gently forward with the trailer brakes locked
  4. D Check only the mirrors for trailer movement

Correct answer: C – Pull gently forward with the trailer brakes locked

Raise the trailer landing gear slightly off the ground before testing the connection. With the trailer brakes still locked, pull the tractor gently forward. The trailer should remain securely attached to the tractor, confirming that the fifth-wheel mechanism has engaged the kingpin before the coupling procedure continues.

Source: California Commercial Driver Handbook — § 6.4.1, “Step 11: Check the Connection for Security”

Question 3

Why must the trailer hand valve not be used to hold a parked trailer?

  1. A Air may leak away and release the trailer brakes
  2. B It can permanently damage the trailer tires
  3. C It prevents the air compressor from operating
  4. D It closes the fifth-wheel locking jaws

Correct answer: A – Air may leak away and release the trailer brakes

The trailer hand valve applies air pressure to the trailer service brakes. If the trailer lacks spring brakes, air may eventually leak away and allow those brakes to release. Use the parking brakes when parking instead. A trailer without spring brakes must also be secured with wheel chocks to prevent movement.

Source: California Commercial Driver Handbook — § 6.2.1, “Trailer Hand Valve”

Question 4

Hard braking locks the trailer wheels and the trailer begins to skid. What should you do?

  1. A Accelerate until the trailer straightens
  2. B Steer sharply away from the skid
  3. C Apply the trailer hand valve
  4. D Release the brakes to restore traction

Correct answer: D – Release the brakes to restore traction

Locked trailer wheels can cause the trailer to swing outward into a jackknife. Release the brakes to allow the wheels to regain traction; once they grip again, the trailer should begin following the tractor. Do not apply the trailer hand valve to straighten the rig because braking the trailer wheels caused the skid.

Source: California Commercial Driver Handbook — § 6.1.5, “Prevent Trailer Skids”

Question 5

How should the service and supply-line shut-off valves be positioned when operating a multiple-trailer combination?

  1. A All supply-line valves open and all service-line valves closed
  2. B All supply-line valves closed and all service-line valves open
  3. C All valves open except those at the rear of the last trailer, which are closed
  4. D The rear valves open and every forward valve closed

Correct answer: C – All valves open except those at the rear of the last trailer, which are closed

Shut-off valves in both the service and supply lines must remain open between the units in the combination. This allows air to travel through the entire rig and operate every trailer’s brakes. The service and supply shut-off valves at the rear of the last trailer must be closed because no additional trailer is connected there.

Source: California Commercial Driver Handbook — § 6.2.7, “Shut-Off Valves”

Question 6

During sudden steering with a set of doubles, which unit faces the greatest rollover risk from the crack-the-whip effect?

  1. A The rear trailer, which may be about twice as likely to roll over as the tractor
  2. B Both trailers, with exactly the same risk
  3. C The front trailer, which is twice as likely to roll over as the tractor
  4. D The tractor and both trailers have equal rollover risk

Correct answer: A – The rear trailer, which may be about twice as likely to roll over as the tractor

Rearward amplification increases the movement transmitted to each unit toward the back of a combination. The rear trailer in a set of doubles can experience the strongest crack-the-whip effect and may be twice as likely to roll over as the tractor. The California handbook emphasizes gentle steering and slow speeds through curves to reduce this risk.

Source: California Commercial Driver Handbook — § 6.1.2, “Steer Gently”

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