California Combination Vehicles CDL Practice Test
Below are 25 exam-style questions for the California Combination Vehicles CDL knowledge test, modeled on the FMCSA-aligned content used by the California Department of Motor Vehicles. Try to answer each question on your own before reading the answer key directly under it. The questions and answer choices are shuffled deterministically per state and endorsement, so the order will stay the same on repeat visits — that lets you genuinely measure your improvement.
- A Performing the seven-step air-brake check before each trip
- B Asking a mechanic
- C Pressing the pedal once at startup
- D Listening to the brake light
- A Brake fade
- B No off-tracking
- C Wheel damage
- D Off-tracking — the trailer wheels follow a tighter arc than the tractor
- A Release the brakes to allow the trailer wheels to roll again, then steer
- B Apply the trailer hand valve harder
- C Accelerate
- D Disconnect the air supply
- A It is fine if you are careful
- B It is the standard procedure
- C It is illegal in some states
- D It can damage the cab and the trailer (cab corner crush)
- A Stop on the tracks if traffic ahead slows
- B Honk and accelerate
- C Shift in the middle of the track
- D Cross in a low gear without shifting
- A Tug the trailer with the trailer parking brakes set
- B Listen for a click
- C Look at the locking jaws only
- D Honk the horn
- A Hold the vehicle when parking
- B Both for parking and to prevent jackknife
- C Test the trailer brakes
- D Apply trailer brakes momentarily
- A Make the truck quieter
- B Only need attention every 5 years
- C Should be replaced when worn beyond manufacturer specs
- D Are normal until the lining is gone
- A GOAL — Get Out And Look — and walk around the trailer first
- B Back at full speed
- C Have the dispatcher in the cab
- D Use only mirrors
- A Trailer wheels lock more often than drive wheels in panic stops
- B Brake balance is irrelevant
- C ABS prevents jackknife in all cases
- D Drive wheels never lock
- A Sliding sideways
- B Loss of traction
- C Driving off the road
- D The trailer wheels follow a tighter arc than the tractor wheels in a turn
- A Disconnected before driving
- B Fully raised before driving
- C Always halfway extended
- D Lowered to the ground while driving
- A By setting the red trailer-air-supply valve
- B By pushing in the red trailer-air-supply valve
- C By the trailer hand valve
- D By pulling out the red trailer-air-supply valve
- A May actually take longer to stop because brakes are designed for the loaded weight
- B Stops only with parking brake
- C Stops faster than when loaded
- D Stops in the same distance
- A Use the trailer hand valve
- B Set both tractor and trailer parking brakes
- C Leave the engine running with the brakes off
- D Set only the tractor parking brake
- A Round, blue, marked TRACTOR
- B Triangular, green, marked SERVICE
- C Square, white, marked CHARGE
- D Octagonal, red, marked TRAILER AIR SUPPLY
- A Driver fatigue
- B Air leakage in the supply line, low pressure, or a brake-balance issue
- C Cargo placement
- D Engine wear
- A The trailer to come uncoupled
- B Engine damage
- C Tire wear only
- D Rust on the cab
- A Coupling with the trailer too high
- B All of the above
- C Failure to grease
- D Backing too fast
- A Lower landing gear, disconnect lines, release fifth wheel, pull tractor away
- B No specific order is required
- C Pull tractor away first, then disconnect lines
- D Release fifth wheel first, then connect lines
- A Honk the horn
- B Drain the air tanks
- C Disconnect the electrical line first
- D Lower the trailer landing gear and chock the trailer wheels
- A Stop traffic by signaling left
- B Stay in the right lane and swing the front of the tractor wide enough to clear the curb without inviting cars to pass on the right
- C Use the shoulder
- D Turn from the left lane
- A Show up only at high speed
- B Need a mechanic to find
- C Can be detected during pre-trip inspection by visual and pressure checks
- D Are caused by low fuel
- A Check that the trailer is stable on its landing gear
- B Disable the trailer parking brake
- C Connect the lines back to the tractor
- D Move the tractor far away immediately without checking
- A Every 3 hours
- B Only at the destination
- C Only at the start of the day
- D Before, during, and after coupling
Study tips for the California Combination Vehicles exam
The Combination Vehicles portion of the California CDL exam is graded out of the bank of questions the California Department of Motor Vehicles draws from each year. While the exact bank is not published, every question is sourced from the Combination Vehicles chapter of the California CDL handbook, which itself is derived from the FMCSA Model Commercial Driver's License Manual. That means studying our practice tests, reading the corresponding handbook chapter, and re-reading the parts you got wrong is genuinely the most efficient route to a first-time pass.
Most successful applicants follow a simple cycle: take the practice test cold, write down every question you missed, open the matching chapter of the official California handbook, re-read the section that contains the right answer, then re-take the practice test 24 to 48 hours later. The 24-hour delay matters — sleep is when your brain commits new information to long-term memory, and CDL knowledge questions reward that kind of consolidated learning rather than cramming.
Pay particular attention to questions that include qualifier words like always, never, only, primary, or most. CDL test writers love to flip the right answer with a single qualifier. When two answer choices look almost identical, pay attention to the verb (is it must, should, or may?) and to any numbers (14 days, 100 air miles, 8 hours, 70/8 split). On endorsement tests in particular, watch for trick framing where a true statement about a different endorsement is offered as the "correct" answer to a question that is actually about Combination Vehicles.
Test-day logistics matter too. Bring photo ID, your Social Security card or birth certificate, your medical examiner's certificate (DOT card), and proof of state residency if you haven't already submitted those documents. The California Department of Motor Vehicles will not let you sit for the knowledge exam without your documentation, and most offices charge an additional fee for re-attempts. Arrive early — the wait at most CDL testing offices runs 30 to 60 minutes — and silence your phone before the exam begins.
Finally, keep your General Knowledge fundamentals sharp even when you're focused on the Combination Vehicles exam. Many states administer multiple knowledge tests in a single sitting, and questions on weight definitions (GVWR, GCWR, GAWR), stopping distance, and the pre-trip inspection routine show up across endorsements. If you're unsure on the basics, sit a fresh California General Knowledge practice test before scheduling the real exam.
Next steps
Missed more than four questions? Re-read the Combination Vehicles study guide and the matching chapter in the official California CDL handbook. Then come back and re-take the test. Once you can score 22 of 25 or higher on three runs in a row, you're in good shape to schedule the real exam at your local California Department of Motor Vehicles office.
Already comfortable with this endorsement? Drill another: CA General Knowledge · CA Air Brakes · CA Hazardous Materials · CA Passenger · CA School Bus · CA Tank Vehicle · CA Doubles / Triples
New to the CDL process in California? Read How to apply for a CDL in California for the document checklist and step-by-step timeline.