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New Jersey CDL permit practice questions, with answers and manual pages

These 18 practice questions cover the three New Jersey Class A knowledge tests, six each, with the answer, an explanation and the manual page for every one. They are original questions written from the New Jersey CDL Manual (March 2025), the book your tests cover, and New Jersey MVC requires 80% to pass.

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General Knowledge

  1. Question 1 · Medical documentation

    You haul a load between two New Jersey towns, and your route passes through part of Pennsylvania before coming back into New Jersey. How does the manual classify this trip for medical self-certification?

    • AIntrastate, because the trip starts and ends in New Jersey
    • BIntrastate, as long as most of the miles are in New Jersey
    • CExcepted, because the out-of-state stretch is short
    • DInterstate, because the truck crosses into another stateAnswer

    A trip between two places in the same state is still interstate commerce if the vehicle crosses into another state for part of the trip. Only driving that stays inside one state and fits none of the interstate cases is intrastate.

    § 1.2.1p. 1-6

  2. Question 2 · CDL disqualifications

    You start across a railroad crossing even though traffic is backed up on the far side, and you end up stopped on the tracks. If you are convicted and it is your first crossing violation, what is the minimum time you will lose your CDL?

    • A120 days
    • B60 daysAnswer
    • COne year
    • DNone, since traffic ahead caused the stop

    Every driver must have enough room to drive all the way through a crossing without stopping. Failing to do so is a crossing violation, and a first violation costs your CDL for at least 60 days.

    § 1.3.5p. 1-8

  3. Question 3 · Other CDL rules

    When you apply for a commercial driving job, how far back must the information you give about your past driving jobs go?

    • AThe past 5 years
    • BThe past 7 years
    • CThe past 3 years
    • DThe past 10 yearsAnswer

    When you apply for a commercial driving job, you must tell the employer about every driving job you have held in the past 10 years.

    § 1.4p. 1-9

  4. Question 4 · Vehicle inspection

    You are well into a trip and have just re-checked your cargo securement. You drive on at a steady 60 mph without stopping. When is your next check due?

    • ANot until you reach the end of the trip
    • BAfter 150 more miles, about 2.5 hours from nowAnswer
    • CAfter 50 more miles, under an hour from now
    • DAfter three more hours, about 180 miles from now

    After the first check, recheck every 150 miles or every three hours, whichever comes first. At 60 mph, 150 miles takes 150 ÷ 60 = 2.5 hours, which is sooner than three hours.

    § 2.1.6p. 2-7

  5. Question 5 · Basic vehicle control

    When you are pulling a trailer, why is it important to speed up smoothly rather than roughly?

    • AJerky starts can damage the couplingAnswer
    • BQuick starts can lock up the trailer brakes
    • CSmooth starts keep the ABS light from coming on
    • DSmooth starts keep the retarder from engaging

    Rough acceleration can cause mechanical damage. When a trailer is hooked up, it can also damage the coupling, so speed up smoothly and gradually.

    § 2.2.1p. 2-8

  6. Question 6 · Shifting gears

    Your truck has a retarder, and the road ahead is wet and icy. What should you do with the retarder?

    • ATurn it on, since it keeps the wheels from skidding
    • BTurn it off, since it may make the drive wheels skidAnswer
    • CUse it only for hard stops on the ice
    • DSet it to full power to save the service brakes

    When the drive wheels have poor traction, a retarder can make them skid. On a wet, icy, or snowy road, switch the retarder off.

    § 2.3.4p. 2-10

Combination Vehicles

  1. Question 7 · Driving combinations safely

    You are pulling a set of doubles on an unlit rural highway at night. How should you choose your speed?

    • AAt the posted speed limit, as long as your high beams are on
    • BFast enough to keep pace with the other traffic around you
    • CClose behind another truck so you can use its taillights
    • DSlow enough to see obstacles in your headlights and stop gentlyAnswer

    At night, keep your speed low enough that your headlights reveal obstacles while there is still time to change lanes or stop gently. Sudden moves with trailers can tip them over.

    § 6.1.2p. 6-1

  2. Question 8 · Combination air brakes

    Your trailer breaks loose from the tractor and tears the emergency air hose apart. What happens to the trailer's brakes?

    • AOnly the tractor's brakes are applied
    • BThe service line takes over supplying the trailer tanks
    • CNothing happens until you press the brake pedal
    • DThe trailer emergency brakes come onAnswer

    The emergency line both fills the trailer tanks and controls the trailer emergency brakes. When it loses pressure, for example because a breakaway tears the hose, the trailer emergency brakes come on and the tractor protection valve closes.

    § 6.2.4p. 6-5

  3. Question 9 · Trailer antilock brakes

    In normal driving, how does the manual tell you to brake a tractor-trailer that has ABS?

    • APump the brakes quickly so the ABS computer can keep up
    • BBrake as you always have, using only the force needed to stop safelyAnswer
    • CBrake harder and later than usual, since ABS will stop any wheel lockup
    • DApply the trailer hand valve first so the trailer ABS can work

    ABS does not call for a special technique in normal driving. Brake the way you always have, using only as much force as you need to stop safely and stay in control, whether ABS is on the tractor, the trailer or both. Section 2 adds one exception: with working ABS on all axles, you can fully apply the brakes in an emergency stop.

    § 6.3.2p. 6-7

  4. Question 10 · Coupling and uncoupling

    In the manual's steps for coupling a gooseneck hitch, what do you do before lowering the trailer's coupler onto the ball?

    • AInstall the safety pin and clip on the coupler
    • BAttach the safety chains and connect the trailer light wiring
    • COpen the clamp latch and make sure the ball is lubricatedAnswer
    • DLower and stow the trailer jacks completely

    Step 1 is to open the clamp latch on the gooseneck coupler and check that the ball is properly lubricated. Then you position the coupler over the ball, lower the trailer and latch the clamp.

    § 6.4.7p. 6-12

  5. Question 11 · Inspecting a combination

    Why does it matter that the tractor protection valve works correctly?

    • AWithout it, a trailer air leak could drain all the tractor's airAnswer
    • BIt stops the trailer brakes from ever applying on their own
    • CIt keeps water and oil out of the trailer air tanks
    • DIt is what controls how hard the trailer service brakes apply in a stop

    A working tractor protection valve keeps a leaking air hose or trailer brake from draining all of the tractor's air. If that happened, the emergency brakes would come on and you could lose control.

    § 6.5.2p. 6-14

  6. Question 12 · Driving combinations safely

    How does the stopping distance of a large combination vehicle change when it is empty instead of fully loaded?

    • AIt stops in a shorter distance
    • BIt takes longer to stopAnswer
    • CIt stops in about the same distance
    • DIt stops shorter but pulls to one side

    An empty or lightly loaded rig has poor traction, so its wheels lock up easily. As a result, a large combination takes longer to stop empty than fully loaded.

    § 6.1.3p. 6-1

Air Brakes

  1. Question 13 · Parts of an air brake system

    The safety relief valve on an air brake system is usually set to open at about what pressure?

    • A55 psi
    • B150 psiAnswer
    • C100 psi
    • D125 psi

    The safety valve sits in the first tank the compressor fills and protects the system from too much pressure. It is usually set to open at 150 psi.

    § 5.1.6p. 5-2

  2. Question 14 · Dual air brake systems

    Why will it take you longer to stop if one half of a dual air brake system is very low on pressure?

    • AThe ABS shuts off whenever one system is low
    • BThe trailer takes all the air from the other half
    • CThe spring brakes will fight the service brakes
    • DThe front or rear brakes won't be fully workingAnswer

    Each half of a dual system works a different set of brakes. If one half is very low, either the front or the rear brakes won't be working fully, so stopping takes longer.

    § 5.2p. 5-5

  3. Question 15 · Inspecting air brakes

    Your truck has a dual air system and minimum-size air tanks. With the engine at operating rpm, pressure takes 70 seconds to climb from 85 to 100 psi. What should you do?

    • ADrive on; up to 90 seconds is normal at operating rpm
    • BDrive on; up to 3 minutes is normal for buildup
    • CDrive on, as long as the governor cuts out at the right pressure
    • DGet it fixed before driving; it should take 45 seconds or lessAnswer

    In a dual air system at operating rpm, pressure should build from 85 to 100 psi within 45 seconds. Slow buildup can let pressure drop too low on the road, so get it fixed before you drive.

    § 5.3.3p. 5-7

  4. Question 16 · Using air brakes

    You have just come down a steep grade, and your brakes are very hot. You are parking on a level lot. How should you hold the vehicle in place?

    • AChock the wheels and let the brakes coolAnswer
    • BLeave it in gear with no brakes or chocks
    • CSet the parking brakes and leave the engine running
    • DSet the parking brakes right away

    Setting the parking brakes on very hot brakes can damage them. Use wheel chocks on a level surface, and let the brakes cool before you use the parking brakes.

    § 5.4.8p. 5-9

  5. Question 17 · Parts of an air brake system

    While building air pressure, you hear the safety valve on the first air tank letting air out. What should you do?

    • ANothing, since it does this at every cut-out
    • BClose the valve by hand to save air
    • CHave a mechanic fix the faultAnswer
    • DDrain the tanks and continue your trip

    The safety valve protects the tanks from too much pressure. If it releases air, something is wrong, and a mechanic should fix the fault.

    § 5.1.6p. 5-2

  6. Question 18 · Dual air brake systems

    You are driving a truck with dual air brakes. The primary gauge looks normal, but the warning light and buzzer come on because the secondary is low. What should you do?

    • APump the brake pedal until the warning goes off
    • BFinish your trip and report it at the end of the day
    • CStop right away and safely park the vehicleAnswer
    • DKeep driving, since the primary system is still full

    If the low air warning comes on while you are driving, stop right away and park safely. Then have the air brake system fixed.

    § 5.2p. 5-5

Sources

New Jersey Commercial Driver License Manual, version March 2025, New Jersey Motor Vehicle Commission. Page references are to its printed page numbers. CDL Mile is independent and not affiliated with the NJ MVC.

Updated for the March 2025 New Jersey CDL manual. Last checked November 5, 2026.

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