California CDL Combination Practice Test (CA) 2

4.9 out of 5 (169 votes)
80% Passing score
20 Questions
4 Mistakes allowed
Prepare for your California CDL Combination endorsement with our comprehensive CDL practice test designed to simulate real-life driving conditions. This California permit practice test is the second in our series, offering you another chance to enhance your knowledge and test your readiness for the endorsement test. Featuring 20 multiple-choice questions, this test covers crucial topics such as inspection procedures, safe driving practices, air brake systems, and more. To pass, you need to answer at least 16 questions correctly. California's diverse driving environments present unique challenges for commercial drivers. Whether navigating the steep grades of the Sierra Nevada, managing the dense traffic of Los Angeles, or contending with the coastal fog near San Francisco, each scenario demands specific skills and knowledge. Our California DMV practice test integrates these real-world conditions, helping you become not just a better test-taker, but a safer, more prepared driver. Understanding the risks of jackknifing, where the trailer swings out of alignment with the tractor, is a key focus. This dangerous situation can occur during sudden braking or improper handling. Our questions and explanations will guide you through the techniques to prevent such incidents, emphasizing smooth braking and careful maneuvering. While this California DMV practice test complements your driver's education, it does not replace a state-certified drivers ed or ELDT course. Instead, use it as a valuable tool to deepen your understanding of the material covered in those courses. After completing the test, take advantage of the review feature to go over your answers. You can see which questions you missed and read detailed explanations and hints to help reinforce your knowledge. By practicing with our test, you'll build the confidence needed to tackle the official test. The varied and realistic questions are designed to ensure you're well-prepared for whatever California's roads might throw at you. Get ready to excel and drive safely across the Golden State with our targeted CDL Combination practice test.
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Sample California Combination Test Questions

Question 1

Which procedure correctly tests a trailer’s emergency brakes?

  1. A Open both air-line valves at the rear of the last trailer
  2. B Move the trailer air supply control to emergency and gently pull against the trailer
  3. C Shut off the engine and repeatedly press the brake pedal
  4. D Release every parking brake and move forward at road speed

Correct answer: B – Move the trailer air supply control to emergency and gently pull against the trailer

First charge the trailer air system and verify that the trailer can roll freely. Stop and pull out the trailer air supply control, or place the control in the emergency position. Then pull gently against the trailer with the tractor. Resistance from the trailer confirms that its emergency brakes have applied.

Source: California Commercial Driver Handbook — § 6.5.2, “Test the Trailer Emergency Brakes”

Question 2

What does rearward amplification do in a multiple-trailer combination?

  1. A It reduces stopping distance at the rear of the rig
  2. B It magnifies movement toward the rear, increasing the last trailer’s rollover risk
  3. C It improves fuel economy by reducing trailer drag
  4. D It keeps every unit on exactly the same path

Correct answer: B – It magnifies movement toward the rear, increasing the last trailer’s rollover risk

Rearward amplification occurs when a steering movement becomes increasingly pronounced as it travels through the combination. The rear trailer can move more sharply than the tractor, particularly during quick lane changes or sudden turns. This crack-the-whip effect makes the last trailer more likely to roll over, so steering inputs should be smooth and gradual.

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

Question 3

The trailer is too high for proper fifth-wheel coupling. What should you do?

  1. A Raise it farther above the fifth wheel
  2. B Back under it at a higher speed
  3. C Approach it at an angle
  4. D Lower it to the correct coupling height

Correct answer: D – Lower it to the correct coupling height

The trailer should be low enough that the tractor raises it slightly while backing the fifth wheel underneath. If the trailer is too high, the kingpin may not couple correctly with the fifth-wheel jaws. Lower the landing gear as needed, then verify that the kingpin and fifth wheel are properly aligned before continuing.

Source: California Commercial Driver Handbook — § 6.4.1, “Step 6: Check the Trailer Height”

Question 4

A trailer breaks away and tears apart both air lines. Besides application of the trailer emergency brakes, what should occur?

  1. A The tractor should immediately lose all reservoir pressure
  2. B The tractor protection valve should close
  3. C The tractor protection valve should open fully
  4. D The trailer air supply control should remain open

Correct answer: B – The tractor protection valve should close

A breakaway causes pressure loss in the trailer emergency, or supply, line. That loss applies the trailer emergency brakes and causes the tractor protection valve to close, usually making the trailer air supply knob pop out. Closing the valve stops air from continuing to escape from the tractor through the damaged trailer lines.

Source: California Commercial Driver Handbook — § 6.2.2, “Tractor Protection Valve”, California Commercial Driver Handbook — § 6.2.4, “Trailer Air Lines”

Question 5

How do you verify that air reaches the brakes on every trailer in a multiple-trailer combination?

  1. A Open each air-line shut-off valve at the rear of the last trailer and listen for escaping air
  2. B Open both air-line valves directly behind the tractor only
  3. C Accelerate and make a hard emergency stop
  4. D Turn off the engine and listen near the tractor’s reservoirs

Correct answer: A – Open each air-line shut-off valve at the rear of the last trailer and listen for escaping air

Secure the vehicle, build normal air pressure, and supply air to the trailers. At the rear of the last trailer, open the emergency-line valve and listen for escaping air, then close it. Apply service pressure, open the service-line valve, listen again, and close it. Air from both lines confirms that the system is charged through the entire combination.

Source: California Commercial Driver Handbook — § 6.5.2, “Check That Air Flows to all the Trailers”

Question 6

After connecting and charging the trailer air lines during coupling, which check helps detect crossed lines and verify brake response?

  1. A Accelerate rapidly before locking the fifth wheel
  2. B Apply and release the trailer brakes while listening for brake movement and escaping air
  3. C Turn the steering wheel while watching the pressure gauge
  4. D Check only the mirrors for movement

Correct answer: B – Apply and release the trailer brakes while listening for brake movement and escaping air

With the engine off, apply and release the trailer brakes while listening carefully. You should hear the brakes move when applied and hear air escape when they are released. The air-pressure gauge should also be observed for signs of major air loss. This check helps identify crossed lines or an improper brake response before coupling continues.

Source: California Commercial Driver Handbook — § 6.4.1, “Step 8: Supply Air to Trailer”

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