South Carolina General Knowledge CDL Prep Test (SC) 4

5 out of 5 (58 votes)
80% Passing score
20 Questions
4 Mistakes allowed
Are you gearing up to take your CDL in South Carolina? Our fourth CDL prep test is a valuable tool in your preparation arsenal. With 20 meticulously crafted CDL written test questions, this prep test is designed to closely mimic the actual DMV permit test in structure and content, ensuring you get the most realistic practice experience. The format of our SC CDL practice test is identical to what you'll encounter at the DMV: a mix of multiple-choice and true/false questions. This approach not only tests your knowledge but also sharpens your skills in identifying the correct answer from several options. It's a practical method to improve your test-taking strategy, crucial for when you sit for the real thing. What sets our SC general knowledge CDL prep test apart is its emphasis on real-life driving situations. We believe that understanding how to apply theoretical knowledge in practical scenarios is vital for any aspiring commercial driver. Therefore, some of our sample CDL questions will plunge you into situations you're likely to face on the road, bridging the gap between theory and real-world application. The content of this South Carolina CDL prep test covers essential areas of driving knowledge. From pre-trip inspections to emergency handling, each question is designed to assess and enhance your understanding of what it takes to be a safe and responsible commercial driver. Topics like vehicle control, cargo transportation, and road sharing are all addressed, ensuring a comprehensive review of crucial driving concepts. Taking this SC DMV practice test multiple times is beneficial as it helps reinforce your learning. The same set of permit test questions will be presented each time, allowing you to track your progress and focus on areas where you need more practice. So, if you're aiming to ace your CDL test in South Carolina in 2026, our fourth CDL prep test is your go-to resource for success!
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Sample South Carolina CDL Test Questions - General Knowledge

Question 1

If a see-through coolant recovery container is not part of the pressurized system, what may you do while the engine is hot?

  1. A Check the level and safely remove that container’s cap to add coolant
  2. B Remove the radiator cap immediately
  3. C Replace the coolant with plain water only
  4. D Drain the engine oil while the engine is running

Correct answer: A – Check the level and safely remove that container’s cap to add coolant

A sight glass or see-through coolant container allows the coolant level to be checked while the engine is hot. If that container is not pressurized, its cap can be safely removed and coolant added at operating temperature. Never open the radiator cap or another pressurized cooling-system component until the system has cooled.

Source: Commercial Driver’s License Manual – 2025 CDL Testing System — § 2.14.1, “Vehicle Checks”

Question 2

When must a truck driver recheck cargo that is accessible for inspection?

  1. A Only before beginning the trip
  2. B At departure and at the first fuel stop only
  3. C Within the first 50 miles, then after a duty-status change or after 3 hours or 150 miles, whichever comes first
  4. D Only after the first 25 miles

Correct answer: C – Within the first 50 miles, then after a duty-status change or after 3 hours or 150 miles, whichever comes first

The federal rule requires cargo and securement to be checked before driving and again within the first 50 miles. Reinspection is then required whenever the driver changes duty status or reaches three hours or 150 miles, whichever occurs first. The South Carolina CDL manual also emphasizes checking after breaks. Exceptions apply when a sealed load may not be opened or the loading method makes inspection impracticable.

Source: Commercial Driver’s License Manual – 2025 CDL Testing System — § 3.1, “Inspecting Cargo”, 49 CFR § 392.9(b)(1)–(4) — Inspection of Cargo, Cargo Securement Devices and Systems

Question 3

Which statement correctly describes stab braking?

  1. A The brakes are applied lightly without releasing them
  2. B The brakes are fully applied, released when the wheels lock, and reapplied after the wheels begin rolling
  3. C The brake pedal is held with steady pressure that prevents wheel lockup
  4. D The brakes remain fully applied while the driver makes a sharp steering correction

Correct answer: B – The brakes are fully applied, released when the wheels lock, and reapplied after the wheels begin rolling

Stab braking begins with a full brake application. When the wheels lock, release the brakes; once the wheels are rolling again, apply them fully. Reapplying too soon can keep the vehicle from straightening. The South Carolina CDL manual distinguishes this method from controlled braking, which avoids locking the wheels.

Source: South Carolina Commercial Driver’s License Manual – 2025 CDL Testing System — § 2.17.2, “How to Stop Quickly and Safely”

Question 4

What functions does the emergency air line perform on a combination vehicle?

  1. A It supplies air to the trailer air tanks
  2. B It controls the trailer emergency brakes
  3. C It performs both functions listed above
  4. D It carries the service-brake application signal only

Correct answer: C – It performs both functions listed above

The emergency, or supply, line fills the trailer air tanks and controls the trailer emergency brakes. A major loss of pressure in this line causes the trailer emergency brakes to apply. The pressure loss also causes the tractor protection valve to close, protecting the tractor’s air supply.

Source: South Carolina Commercial Driver’s License Manual – 2025 CDL Testing System — § 6.2.4, “Trailer Air-lines”

Question 5

Which combination is especially likely to become stuck on a raised railroad crossing?

  1. A A tractor with a damaged steering tire
  2. B A straight truck with a manual transmission
  3. C A low-slung trailer or a single-axle tractor pulling a long trailer
  4. D A vehicle equipped with hydraulic brakes

Correct answer: C – A low-slung trailer or a single-axle tractor pulling a long trailer

Low-slung units can hang up where a railroad crossing rises sharply. Examples include lowboys, car carriers, moving vans, and possum-belly livestock trailers. The South Carolina CDL manual also identifies a long trailer pulled by a single-axle tractor when its landing gear is set for a tandem-axle tractor.

Source: South Carolina Commercial Driver’s License Manual – 2025 CDL Testing System — § 2.15.6, “Special Situations”

Question 6

A yellow diamond-shaped sign displaying a black truck symbol warns that:

This sign warns drivers to _____________.
  1. A A railroad crossing is immediately ahead
  2. B Only commercial vehicles may use the road ahead
  3. C Passenger vehicles must remain in the left lane
  4. D Trucks may unexpectedly enter or cross the roadway

Correct answer: D – Trucks may unexpectedly enter or cross the roadway

A Truck Crossing warning sign alerts road users to a location where truck traffic may unexpectedly enter or cross the roadway. It may be used where the activity or entering traffic is not readily anticipated. Drivers should recognize it as a warning of possible truck movements, not as a truck-only route designation.

Source: Manual on Uniform Traffic Control Devices for Streets and Highways, 11th ed., Rev. 1 — Ch. 2C, “Vehicular Traffic Warning Signs” (W8-6 and W11-10)

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