South Carolina CDL Combination Test (SC) 2026

5 out of 5 (52 votes)
80% Passing score
20 Questions
4 Mistakes allowed
Gain the confidence and knowledge you need to secure your Commercial Driver's License (CDL) combination vehicles endorsement with our South Carolina DMV practice test. This comprehensive test is specifically designed for those preparing to drive combination vehicles, which present unique challenges due to their size and complexity. With our SC combination CDL practice test, you'll cover all crucial areas including coupling and uncoupling procedures, pre-trip inspections, effective driving techniques, backing and maneuvering, and air brake systems. The SC combination vehicle test consists of 20 multiple-choice questions. To pass, you need to answer at least 16 questions correctly, ensuring you have a solid grasp of the material. Our practice test goes beyond simple rote memorization, incorporating real-life driving scenarios that help you apply your knowledge in practical situations. This approach not only prepares you for the written test but also makes you a safer, more effective driver on the road. Understanding the increased stopping distances required for combination vehicles is a key focus of our South Carolina combination CDL practice test. Given the greater weight of these vehicles, knowing how to manage stopping distances is critical for maintaining safety. Our permit test practice ensures you are well-versed in this and other essential topics, giving you the skills you need to handle the unique challenges posed by larger, heavier vehicles. At the end of each CDL combination practice test, you'll receive a detailed summary of your performance. This summary highlights the questions you answered incorrectly and provides the correct answers, helping you learn and improve. This immediate feedback is invaluable for reinforcing your knowledge and identifying areas where you may need further study. Our SC DMV practice test is tailored to the specific rules, regulations, and road signs of SC, ensuring that you're studying the most relevant material for your state. Whether you're new to driving combination vehicles or looking to refresh your knowledge, our South Carolina combination vehicle test is an essential resource for your preparation.
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Sample South Carolina Combination Test Questions

Question 1

Why should the trailer hand valve not be used to hold a parked trailer?

  1. A On a trailer without spring brakes, air may leak away and release the brakes
  2. B It applies excessive pressure to the trailer tires
  3. C It immediately empties the tractor’s service reservoirs
  4. D It prevents the fifth wheel from being uncoupled

Correct answer: A – On a trailer without spring brakes, air may leak away and release the brakes

The trailer hand valve depends on air pressure and is not a parking-brake control. On trailers without spring brakes, air can eventually leak away and allow the brakes to release. Use the parking brakes when parking, and secure a trailer without spring brakes with wheel chocks.

Source: South Carolina Commercial Driver’s License Manual — § 6.2.1, “Trailer Hand Valve”

Question 2

After coupling a tractor-semitrailer, how must the landing gear be positioned before driving?

  1. A Raised one-third, with the crank handle secured
  2. B Raised halfway, with the crank handle secured
  3. C Raised three-quarters, with the crank handle secured
  4. D Raised completely, with the crank handle secured

Correct answer: D – Raised completely, with the crank handle secured

The landing gear must be raised completely before the combination is driven. Partially raised landing gear can catch on railroad tracks or other objects and damage the trailer. South Carolina’s coupling procedure also requires the crank handle to be secured after the supports are fully raised.

Source: South Carolina Commercial Driver’s License Manual — § 6.4.1, “Step 15. Raise Front Trailer Supports (Landing Gear)”

Question 3

During a static leakage test on a combination vehicle, the air-pressure loss should be less than how many psi in one minute?

  1. A 1 psi
  2. B 2 psi
  3. C 3 psi
  4. D 4 psi

Correct answer: C – 3 psi

With the air system fully charged, turn off the engine, release the parking brakes, and observe the pressure drop without applying the service brakes. A combination vehicle should lose less than 3 psi in one minute. This differs from the applied-brake leakage test, which uses a higher limit.

Source: South Carolina Commercial Driver’s License Manual — § 5.3.3, “Test Air Leakage Rate”

Question 4

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

  1. A Any tank trailer, regardless of ground clearance
  2. B Any trailer carrying placarded hazardous materials
  3. C A low-slung trailer or a long trailer pulled by a single-axle tractor with landing gear set for a tandem-axle tractor
  4. D Any trailer equipped with tandem axles

Correct answer: C – A low-slung trailer or a long trailer pulled by a single-axle tractor with landing gear set for a tandem-axle tractor

South Carolina’s CDL manual identifies low-slung units—including lowboys, car carriers, moving vans, and possum-belly livestock trailers—as vulnerable at raised crossings. A long trailer pulled by a single-axle tractor can also become stuck when its landing gear was positioned to provide clearance for a tandem-axle tractor.

Source: South Carolina Commercial Driver’s License Manual — § 6.1.4, “Railroad-highway Crossings”

Question 5

When standard color coding is used on combination-vehicle air lines, which colors identify the emergency and service lines?

  1. A Black for emergency; yellow for service
  2. B Blue for emergency; red for service
  3. C Red for emergency; blue for service
  4. D Yellow for emergency; black for service

Correct answer: C – Red for emergency; blue for service

Color coding helps drivers connect the correct glad hands. Red is used for the emergency or supply line, while blue is used for the service line. Metal tags stamped with “service” and “emergency” may also identify the lines, so drivers should verify the markings when coupling.

Source: South Carolina Commercial Driver’s License Manual — § 6.2.5, “Hose Couplers (Glad Hands)”

Question 6

What is the function of the trailer air supply control?

  1. A It is the yellow parking-brake control for the tractor
  2. B It mechanically keeps the trailer attached to the fifth wheel
  3. C It directly seals a broken trailer air line
  4. D It supplies air to the trailer or shuts off the air and applies the trailer emergency brakes

Correct answer: D – It supplies air to the trailer or shuts off the air and applies the trailer emergency brakes

On newer vehicles, the trailer air supply control is a red, eight-sided knob that operates the tractor protection valve. Pushing it in supplies air to the trailer. Pulling it out shuts off that supply and applies the trailer emergency brakes.

Source: South Carolina Commercial Driver’s License Manual — § 6.2.3, “Trailer Air Supply Control”

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