South Carolina CDL General Knowledge Test (SC) 5

4.9 out of 5 (63 votes)
80% Passing score
50 Questions
10 Mistakes allowed
Greetings to all aspiring commercial drivers in South Carolina! As you navigate the path to obtaining your Commercial Driver's License (CDL), our fifth SC CDL General Knowledge Practice Test stands ready to assist you. With a set of 50 carefully crafted DMV questions, this test is a crucial tool in your preparation arsenal. Remember, while our South Carolina DMV CDL practice test is an invaluable resource, it's important to recognize that it complements, but does not replace, the traditional drivers education programs (known as Entry Level Driver Training, or ELDT, by commercial drivers) required by South Carolina. Completing a state-certified driver's education course is mandatory for acquiring your CDL. Our DMV practice test works hand in hand with these courses, filling in gaps and reinforcing your knowledge. The sample questions in this SC permit practice test are designed to offer an authentic practice experience. While we don't have access to the actual DMV test questions, our materials closely emulate the structure and content of the real SC CDL permit test. This method is particularly beneficial for those who thrive on understanding the core concepts and practical application, rather than just memorizing facts. Each time you take this South Carolina DMV practice test, you'll encounter the same 50 questions and answers, enabling you to measure your improvement and focus on areas that need more attention. A score of 40 or more is required to pass, aligning with the DMV standards. Utilize this South Carolina CDL general knowledge practice test to ensure you're not only prepared for the CDL written test but also deeply familiar with the types of questions you'll face. This DMV practice test is more than just a study aid - it's a strategic step towards achieving your goal of becoming a licensed commercial driver in South Carolina in 2026!
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Sample South Carolina CDL Test Questions - General Knowledge

Question 1

Underinflated tires are a possible cause of vehicle fires.

  1. A True
  2. B False

Correct answer: A – True

Underinflated tires are specifically identified as a possible cause of vehicle fires. Dual tires that touch each other are another listed tire-related cause. Drivers should inspect tires before a trip and check tires, wheels, and the vehicle body for signs of excessive heat whenever they stop during a trip.

Source: South Carolina Commercial Driver’s License Manual – 2025 CDL Testing System — §§ 2.21.1–2.21.2, “Causes of Fire” and “Fire Prevention”

Question 2

Which is one basic reason for covering cargo carried on an open bed?

  1. A To prevent theft during every stop
  2. B To improve the vehicle’s weight distribution
  3. C To protect the cargo from weather
  4. D To eliminate the need for cargo inspections

Correct answer: C – To protect the cargo from weather

One basic reason for covering an open-bed load is to protect the cargo from weather. The other is to protect people from cargo that might spill. Drivers should also monitor the cover while traveling because a loose or flapping cover can tear away and expose the load.

Source: South Carolina Commercial Driver’s License Manual – 2025 CDL Testing System — § 3.3.4, “Covering Cargo”

Question 3

How should you check a hydraulic brake system for a possible leak while the vehicle is stopped?

  1. A Check only the brake-fluid level; no pedal test is needed
  2. B Roll forward slowly and make a hard stop
  3. C Pump the pedal three times, hold firm pressure for five seconds, and check for pedal movement
  4. D Press the brake and accelerator pedals at the same time

Correct answer: C – Pump the pedal three times, hold firm pressure for five seconds, and check for pedal movement

For this South Carolina CDL inspection procedure, pump the hydraulic brake pedal three times and then hold firm pressure for five seconds. The pedal should not continue moving downward. Movement can indicate a leak or another braking-system problem, and the problem must be repaired before the vehicle is driven.

Source: South Carolina Commercial Driver’s License Manual – 2025 CDL Testing System — § 2.1, “Step 7: Start the Engine and Check”

Question 4

What does gross combination weight (GCW) measure?

  1. A The combined weight of the cargo, driver, and passengers only
  2. B The manufacturer’s maximum rated weight for the combination
  3. C The actual weight of the trailer and its cargo only
  4. D The actual weight of the power unit, towed units, and their loads

Correct answer: D – The actual weight of the power unit, towed units, and their loads

Gross combination weight is the actual weight of a combination, including the power unit, the towed vehicle or vehicles, and the load being carried. It differs from gross combination weight rating, which is a rated value used to classify a vehicle or combination. The driver, fuel, equipment, and cargo contribute to actual weight as applicable.

Source: 49 CFR § 390.5 – Definitions

Question 5

Most regulatory traffic signs use which basic shape?

Many _____________ are this shape.
  1. A Diamond
  2. B Rectangle
  3. C Circle
  4. D Pennant

Correct answer: B – Rectangle

Regulatory signs are generally rectangular unless a different shape is specifically designated. Familiar exceptions include the octagonal STOP sign and triangular YIELD sign. Regulatory signs communicate traffic laws or requirements, while diamond-shaped signs generally warn of conditions ahead.

Source: Manual on Uniform Traffic Control Devices for Streets and Highways, 11th ed., Rev. 1 — § 2B.02, “Design of Regulatory Signs”

Question 6

When starting a manual-transmission CMV on dry, level pavement, which actions are not part of a normal smooth start?

  1. A Accelerating hard and releasing the clutch suddenly
  2. B Applying the parking brake solely to prevent rollback when the vehicle will not roll
  3. C Both actions listed above

Correct answer: C – Both actions listed above

A driver should accelerate smoothly and gradually rather than applying excessive power or suddenly releasing the clutch. The parking brake is used when necessary to prevent the vehicle from rolling backward. On dry, level pavement with no rollback risk, that use of the parking brake is normally unnecessary.

Source: South Carolina Commercial Driver’s License Manual – 2025 CDL Testing System — § 2.2.1, “Accelerating”, South Carolina Commercial Driver’s License Manual – 2025 CDL Testing System — § 13.1.11(a), “Clutch Usage”

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