California CDL Practice Test: General Knowledge (CA) 6

4.9 out of 5 (191 votes)
80% Passing score
50 Questions
10 Mistakes allowed
Preparing for the California CDL General Knowledge exam is a crucial step towards a career in commercial driving. Our sixth CA CDL practice test is designed to provide a solid foundation in the essentials. Featuring a set of 50 questions, the DMV practice test requires at least 40 correct answers to pass. The questions delve into important topics such as vehicle equipment, emergency procedures, accident protocols, pre-trip inspections, and even fundamental aspects of handling hazardous materials, knowledge that's vital for every aspiring driver. As you progress through the test, you'll receive instant feedback on each answer, complete with detailed explanations that clarify concepts and rectify misunderstandings. This feature is invaluable for learning and retaining information. The format and content of our practice questions are closely aligned with the actual California DMV general knowledge test, providing a realistic practice experience that prepares you for what to expect on exam day. To prevent learning by rote and to promote a deeper understanding of the material, our California CDL practice test test offers a fresh set of randomized questions with each attempt. This strategy ensures that you're not just memorizing sequences but are truly comprehending the critical information necessary to navigate the responsibilities of commercial driving safely and confidently.
FREE CDL Practice Test App
Pass your California CDL General Knowledge test with the NextDoorDriving app. Real questions and answers—100% free and ad-free.
Download on the App Store

Sample California CDL Test Questions - General Knowledge

Question 1

How must you respond to a flashing red traffic signal?

  1. A Stop, then proceed only when permitted and safe
  2. B Slow down and continue without stopping
  3. C Proceed as though the signal were green
  4. D Yield without making a complete stop

Correct answer: A – Stop, then proceed only when permitted and safe

Under California law, a flashing red signal requires a complete stop before entering the intersection. After stopping, you may proceed subject to the rules that apply after stopping at a STOP sign. A flashing red signal is not treated as a flashing yellow signal or a green light.

Source: CVC § 21457(a)

Question 2

In California, operating a vehicle after taking a drug that makes you unable to drive safely is:

  1. A Permitted if the drug was prescribed
  2. B Unlawful
  3. C Permitted if it is an over-the-counter cold medicine
  4. D Acceptable if the drug is combined with a small amount of alcohol

Correct answer: B – Unlawful

State law makes it unlawful to drive while under the influence of any drug. Prescription and over-the-counter medicines can cause drowsiness or otherwise interfere with safe driving. A drug's lawful availability does not permit a driver to operate a vehicle while impaired by it.

Source: California Commercial Driver Handbook — § 2.22.2, “Other Drugs”, CVC § 23152(f)

Question 3

If you are forced off the roadway, avoid braking, if possible, until your speed falls to about:

  1. A 10 mph
  2. B 20 mph
  3. C 25 mph
  4. D 30 mph

Correct answer: B – 20 mph

When leaving the roadway, avoid using the brakes, if possible, until the vehicle slows to about 20 mph. Then brake very gently because a loose surface provides less traction. Keep one set of wheels on the pavement when possible and remain on a clear shoulder until the vehicle stops.

Source: California Commercial Driver Handbook — § 2.17.1, “Leaving the Road”

Question 4

What are the two functions of a combination vehicle's emergency air line?

  1. A It supplies air to the trailer air tanks
  2. B It controls the trailer emergency brakes
  3. C It performs both functions
  4. D It applies the trailer service brakes during normal braking only

Correct answer: C – It performs both functions

The emergency, or supply, line supplies air to the trailer air tanks and controls the emergency brakes. If pressure is lost in this line, the trailer emergency brakes apply and the tractor protection valve closes. The service line performs a different function by carrying the normal braking signal.

Source: California Commercial Driver Handbook — § 6.2.4, “Trailer Air Lines”

Question 5

Why should you back toward the driver's side whenever possible?

  1. A It is required for every backing maneuver
  2. B It always shortens the maneuver
  3. C It gives you a better view of the rear of the vehicle
  4. D It eliminates the need to use both mirrors

Correct answer: C – It gives you a better view of the rear of the vehicle

Driver-side backing provides better visibility than backing toward the right. When you back and turn toward the driver's side, you can watch the rear of the vehicle through the side window while continuing to use both outside mirrors. Better visibility makes it easier to identify hazards and correct the vehicle's path.

Source: California Commercial Driver Handbook — § 2.2.4, “Backing Safely”

Question 6

Which conditions are brake defects that should be identified during an inspection?

  1. A Cracked brake drums
  2. B Brake shoes or pads contaminated by oil, grease, or brake fluid
  3. C Brake shoes that are dangerously thin, missing, or broken
  4. D All of the above

Correct answer: D – All of the above

Brake drums must be checked for cracks. Shoes and pads must not be contaminated with oil, grease, or brake fluid because contamination reduces friction. Shoes that are dangerously thin, missing, or broken are also serious defects, making every listed condition a correct inspection concern.

Source: California Commercial Driver Handbook — § 2.1.3, “Bad Brake Drums or Shoes”

More California CDL Practice Tests
Other CDL Endorsements