South Dakota CDL Combination Test (SD) 2026

5 out of 5 (37 votes)
80% Passing score
20 Questions
4 Mistakes allowed
Prepare thoroughly for your Commercial Driver's License (CDL) combination vehicles endorsement with our SD CDL combination practice test. This comprehensive South Dakota practice permit test features a wide array of multiple-choice questions that cover all crucial areas, including coupling and uncoupling, pre-trip inspections, driving techniques, backing and maneuvering, and air brake systems. Each drivers test practice includes 20 questions, and you'll need to get at least 16 correct answers to pass. One key topic you'll explore is the increased stopping distances required for combination vehicles due to their greater weight. Understanding this critical aspect is vital for ensuring safety on the road and effectively managing the unique challenges posed by larger, heavier vehicles. To help you study more efficiently, the South Dakota DMV driving test practice offers various study aids. If you find yourself stuck on a challenging question, you can request a hint that will guide you toward the correct answer. Additionally, if you answer a question incorrectly, the DMV practice test provides immediate feedback along with a detailed explanation. This feature helps you understand why a particular answer is correct or incorrect, thereby enhancing your learning process. The SD drivers license practice is specifically tailored to focus on the combination vehicle endorsement, ensuring that you are only studying the relevant material that will appear on the CDL permit test for this endorsement. It's important to note that to obtain a commercial driver's license, you must also pass the general knowledge test. If you need assistance with this, we offer general knowledge prep tests as well. By focusing on these specific areas, the combination CDL test ensures that you are well-prepared to handle the demands of driving combination vehicles. Whether you are new to the field or looking to refresh your knowledge, our South Dakota combination vehicle test is an invaluable resource for achieving your CDL endorsement and advancing your driving career.
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Sample South Dakota Combination Test Questions

Question 1

Which feature normally identifies an ABS-equipped trailer?

  1. A Every trailer has ABS, so no indicator is needed
  2. B The wheels lock during a high-speed brake test
  3. C A yellow malfunction lamp is located on the trailer’s left side
  4. D The trailer is equipped with spring brakes

Correct answer: C – A yellow malfunction lamp is located on the trailer’s left side

The South Dakota Commercial Driver License Manual states that an ABS-equipped trailer normally has a yellow malfunction lamp on its left side, at either the front or rear corner. Older trailers may have ABS even when identification is difficult. In that situation, look underneath for the electronic control unit and wheel-speed-sensor wires.

Source: South Dakota Commercial Driver License Manual — § 6.3.1, “Trailers Required to Have ABS”

Question 2

After connecting the air lines and supplying air to a trailer, which check helps verify that its brakes respond?

  1. A Accelerate the tractor sharply
  2. B Apply and release the trailer brakes while listening for their operation
  3. C Watch the mirrors for trailer movement
  4. D Turn the steering wheel from side to side

Correct answer: B – Apply and release the trailer brakes while listening for their operation

With normal air pressure established, shut off the engine and apply and release the trailer brakes. You should hear the brakes move when applied and hear air escape when they are released. Also watch the air-pressure gauge for evidence of a major air loss before continuing the coupling procedure.

Source: South Dakota Commercial Driver License Manual — § 6.4.1, “Coupling Tractor-Semitrailers”

Question 3

What is the primary coupling risk when a semitrailer is positioned too high?

  1. A The trailer will immediately begin rolling
  2. B The air lines cannot be attached
  3. C The electrical cord cannot reach
  4. D The kingpin and fifth wheel may not couple correctly

Correct answer: D – The kingpin and fifth wheel may not couple correctly

Before backing under the trailer, adjust its height so the tractor raises it slightly during coupling. If the trailer is too high, the fifth wheel may pass beneath the apron without correctly engaging the kingpin. The driver must lower the trailer and verify proper alignment before continuing.

Source: South Dakota Commercial Driver License Manual — § 6.4.1, “Coupling Tractor-Semitrailers”

Question 4

For a truck tractor whose trailer blocks the direct rear view, where must the required outside rear-vision mirrors be located?

  1. A One on the left side and one on the right side
  2. B On the left side only
  3. C On the right side only
  4. D No outside mirrors are required

Correct answer: A – One on the left side and one on the right side

Federal motor carrier equipment rules require a truck tractor to have two outside rear-vision mirrors, one on each side. They must be firmly attached and positioned to reflect the highway to the rear along both sides of the vehicle. A mirror on only one side would not satisfy this requirement for the described combination.

Source: 49 CFR § 393.80(a) – Rear-vision mirrors

Question 5

If a trailer breaks away and separates both air lines, what should happen in addition to the trailer emergency brakes applying?

  1. A The tractor should lose all stored air
  2. B The tractor protection valve should close
  3. C The tractor protection valve should remain open
  4. D The trailer air-supply control should remain pushed in

Correct answer: B – The tractor protection valve should close

A breakaway causes pressure to disappear from the trailer emergency line, applying the trailer emergency brakes. The pressure loss also closes the tractor protection valve and normally causes the trailer air-supply knob to pop out. Closing the valve prevents air from continuing to escape from the tractor through the separated lines.

Source: South Dakota Commercial Driver License Manual — § 6.2.4, “Trailer Air Lines”

Question 6

It is safe to drive after raising the landing gear only a few inches above the pavement. True or false?

  1. A True
  2. B False

Correct answer: B – False

Before driving, raise the landing gear completely and secure the crank handle. Landing gear left partly down can catch on railroad tracks or other objects. Once the trailer’s weight is on the tractor, also verify adequate clearance between the landing gear and tractor frame and between the tractor tires and trailer nose.

Source: South Dakota Commercial Driver License Manual — § 6.4.1, “Coupling Tractor-Semitrailers”

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