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Washington CDL practice test

Getting a commercial driver's licence in Washington starts with the CDL knowledge tests. The content is federal: every state, Washington included, writes its tests from the FMCSA CDL manual, so the general knowledge test has 50 questions, the endorsement tests have 20 to 30, and the passing score is 80% on each. The Washington driver licensing agency administers the test; the rules behind it are published by the FMCSA. Try the free Washington CDL practice questions below, then pick a full test.

Free Washington CDL practice questions

Five questions from the general knowledge, air brakes and combination vehicles banks, the three tests most Washington Class A applicants take first. Show the answer to read the explanation.

  1. The service air line carries air to the trailer brakes whenever you:

    • Press the brake pedal or use the trailer hand valve
    • Push in the red trailer air supply knob
    • Start the engine
    • Pull out the yellow parking brake knob
    Show answer
    Answer: A. Press the brake pedal or use the trailer hand valve

    The service line is controlled by the foot brake and the hand valve. How hard you press sets how much pressure goes down the line and how hard the trailer brakes apply.

    Source: FMCSA CDL Manual, Section 6.2.4 (Service Air Line)

  2. What happens if the emergency (supply) line breaks or pulls loose while you are driving?

    • The trailer brakes release and the trailer rolls free
    • Nothing, as long as the service line is still connected
    • The trailer emergency brakes come on and the tractor protection valve closes
    • The tractor loses all its brakes
    Show answer
    Answer: C. The trailer emergency brakes come on and the tractor protection valve closes

    Air pressure in the emergency line is what keeps the trailer emergency brakes released. Lose it and the trailer brakes apply, while the tractor protection valve keeps the tractor's air from escaping.

    Source: FMCSA CDL Manual, Section 6.2.4 (Emergency Air Line)

  3. To connect a pair of glad hands correctly, you should:

    • Push them straight together and tape the joint
    • Screw them together clockwise until tight
    • Hold them together by hand while a helper charges the system
    • Press the two seals together with the couplers at a 90-degree angle to each other, then turn the glad hand on the hose to lock them
    Show answer
    Answer: D. Press the two seals together with the couplers at a 90-degree angle to each other, then turn the glad hand on the hose to lock them

    The rubber seals must meet cleanly and the couplers must lock. Check that the seals are in good condition and free of dirt, because a leak here can leave you without trailer brakes.

    Source: FMCSA CDL Manual, Section 6.2.5 (Hose Couplers)

  4. When you are driving without a trailer, the tractor's air hose couplers (glad hands) should be:

    • Connected to dummy couplers or to each other, to keep water and dirt out
    • Left hanging free so they dry out
    • Removed and stored in the cab
    • Taped shut with duct tape
    Show answer
    Answer: A. Connected to dummy couplers or to each other, to keep water and dirt out

    Dirt or water in the air lines can damage the system and cause brake trouble. Most tractors have dead-end (dummy) couplers; if not, couple the two glad hands to each other.

    Source: FMCSA CDL Manual, Section 6.2.5 (Hose Couplers)

  5. You cross the air lines when coupling (service to emergency and emergency to service) on an older trailer that has no spring brakes. What could happen?

    • The trailer brakes would lock and the rig could not move
    • The tractor parking brake would release on its own
    • You could drive away, but you would have no trailer brakes
    • Nothing, because the glad hands are interchangeable
    Show answer
    Answer: C. You could drive away, but you would have no trailer brakes

    Crossed lines send supply air down the service line instead of charging the trailer tanks. With spring brakes you could not move, which warns you, but a trailer without spring brakes can roll away with no brakes at all.

    Source: FMCSA CDL Manual, Section 6.2.5 (Hose Couplers)

Every CDL test for Washington drivers

Each page has ten free sample questions, the real question count, the 80% pass mark and what the test covers.

How the Washington CDL knowledge test works

You take the general knowledge test first; it is required for every CDL class. Class A drivers add the combination vehicles test. Almost everyone takes the air brakes test, because skipping it puts an air brake restriction on the licence. Endorsements (hazmat, tanker, doubles/triples, passenger, school bus) each have their own knowledge test. Pass the tests and you hold a commercial learner's permit; the skills test in a truck comes later.

Fees, appointment rules and test centre locations are set by Washington and change over time, so check the state driver licensing agency before you go. What does not change is the content, and that is what PassRig drills.

Washington CDL test questions

How many questions are on the Washington CDL test?

The Washington CDL general knowledge test follows the federal model: 50 questions, 40 correct to pass. Endorsement tests are shorter: air brakes 25, hazmat 30, and combination vehicles, tanker, doubles/triples, passenger and school bus 20 each.

What is the passing score on the Washington CDL permit test?

80% on every knowledge test, the same pass mark used across the United States.

Where do I take the CDL knowledge test in Washington?

At the Washington state driver licensing agency (the DMV, DOT or equivalent). Check its website for locations, appointments and current fees; the test content itself comes from the FMCSA CDL manual.

Does PassRig have Washington CDL practice questions?

Yes. Pick Washington in the app and you get practice sets and mock exams built from the knowledge test content your state uses, with the real counts and the 80% line.

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