PracticeVideosBlogFlashcardsEspañol
All Practice Exams

Free Practice Questions for Idaho CDL Air Brakes

Exam-style questions and explanations by OpenExamPrep.

✓ No registration✓ No credit card
132+ Questions
100% Free

Loading practice questions...

Same family resources

Explore More CDL Air Brakes Knowledge Test

Continue into nearby exams from the same family. Each card keeps practice questions, study guides, flashcards, videos, and articles in one place.

Alabama CDL Air Brakes Knowledge Test

Practice QuestionsNational Study Guide7 Job Wiki

Arkansas CDL Air Brakes Knowledge Test

Practice QuestionsNational Study Guide7 Job Wiki

California CDL Air Brakes Knowledge Test

Practice QuestionsNational Study Guide7 Job Wiki

Colorado CDL Air Brakes Knowledge Test

Practice QuestionsNational Study Guide7 Job Wiki

Florida CDL Air Brakes Knowledge Test

Practice QuestionsNational Study Guide7 Job Wiki

Georgia CDL Air Brakes Knowledge Test

Practice QuestionsNational Study Guide7 Job Wiki
Exam Review

Key Facts: Idaho CDL Air Brakes Exam

80%

Federal minimum correct score for the air-brake knowledge component

49 CFR 383.135

$5

Idaho fee for each CDL knowledge-test attempt

ITD CDL fee schedule

L

Restriction when full air-brake qualification is not demonstrated

ITD CDL page and 49 CFR 383.95

Z

Restriction after skills testing in air-over-hydraulic equipment

ITD CDL page and 49 CFR 383.95

Not published

Current official Air Brakes knowledge-test item count and time limit

ITD public CDL sources reviewed 2026-10-03

Study Idaho CDL Manual Section 5 and practice the air-brake inspection in the actual vehicle. Idaho charges $5 per knowledge-test attempt and applies the 80% federal knowledge standard, but ITD does not publish a current Air Brakes item count or time limit.

Sample Idaho CDL Air Brakes Practice Questions

Try these sample questions to review concepts for the Idaho CDL Air Brakes exam. Each question includes a detailed explanation. Start the interactive quiz above for the full 132+ question experience with AI tutoring.

1When must Idaho place restriction L on a CLP or CDL issued to an applicant?
A.After failing the air-brake knowledge component or taking the skills test in a vehicle without air brakes
B.Whenever the applicant tests in a vehicle with air-over-hydraulic brakes, even after passing the knowledge test
C.Whenever the applicant holds a Class C CDL
D.Only after an air-brake traffic citation
Explanation: Restriction L bars operation of a CMV equipped with any type of air brakes. It applies when the applicant fails the air-brake knowledge component or performs the skills test in a vehicle without air brakes.
2An Idaho applicant performs the CDL skills test in a vehicle with air-over-hydraulic brakes. Which restriction applies?
A.Restriction L, which bars every air-brake system
B.Restriction Z, which bars CMVs operating fully on the air-brake principle
C.Restriction M, which bars Class A buses
D.Restriction E, which bars manual transmissions
Explanation: Restriction Z applies when the representative skills-test vehicle uses air-over-hydraulic brakes. It prevents the driver from operating a CMV with a braking system that operates fully on the air-brake principle.
3What does ITD charge for an Air Brakes knowledge-test attempt, and when may an applicant retest after failing?
A.$20, after 14 days
B.$29, after 30 days
C.$5, after three days
D.$5, immediately on the same test version
Explanation: ITD charges $5 for each CDL knowledge or endorsement knowledge test. Its current CDL guide says a failed applicant may retest after three days; federal rules require a different version on a retake.
4What must an Idaho driver demonstrate to remove restriction L from a CDL?
A.A mechanic's signed statement that the vehicle has air brakes, plus one year of documented work driving it
B.Only the general-knowledge test
C.One year of work in an air-brake vehicle
D.The air-brake knowledge test and the required skills demonstration in an air-brake-equipped CMV
Explanation: ITD states that a driver must pass the air-brake knowledge test and a skills test in a vehicle equipped with air brakes to avoid or remove restriction L. The practical component includes the required air-brake inspection demonstration; written study cannot replace it.
5During an Idaho CDL air-brake inspection, when must the low-air warning activate?
A.Only after pressure falls far enough for the spring brakes to begin applying automatically
B.At exactly 20 psi
C.Only when both gauges reach zero
D.Before pressure in either reservoir falls below 55 psi
Explanation: The Idaho CDL Manual says the low-air warning must activate before pressure falls below 55 psi in either reservoir. Some newer vehicles warn at a higher pressure, but waiting for spring-brake application is too late.
6While fanning the brakes during the parking-brake pop-out test, when should the parking-brake valve normally close?
A.At the manufacturer's specified pressure in the 20-to-45 psi range
B.At the same 55-to-60 psi threshold used for low-air warning activation in older vehicles
C.At approximately 100 psi
D.Between 120 and 140 psi
Explanation: The Idaho CDL Manual gives a typical parking-brake valve pop-out range of 20 to 45 psi, subject to the manufacturer's specification. Pop-out causes the spring brakes to apply as system pressure is depleted.
7A combination vehicle loses 5 psi in one minute with the engine off and the service brake firmly applied. How should the applicant evaluate the result?
A.Pass, because up to 6 psi per minute is permitted
B.Fail, because the applied-loss limit for a combination vehicle is 4 psi per minute
C.Pass, because leakage limits apply only to single vehicles
D.Fail only if the parking-brake valve also pops out
Explanation: The Idaho CDL Manual permits no more than 4 psi of loss in one minute for a combination vehicle during the applied leakage test. A 5-psi loss exceeds that limit and indicates an air leak that must be corrected.
8At operating engine speed, how quickly should a standard dual air system build from 85 to 100 psi?
A.Within 15 seconds
B.Within 30 seconds
C.Within 45 seconds
D.Within three minutes
Explanation: The Idaho CDL Manual states that pressure should build from 85 to 100 psi within 45 seconds in a dual air system at operating rpm. Vehicles with larger-than-minimum tanks may have a different safe buildup time specified by the manufacturer.
9Before driving a dual-air-system vehicle, what minimum pressure should both the primary and secondary systems show?
A.55 psi
B.80 psi
C.100 psi
D.At least 150 psi in each circuit
Explanation: The Idaho CDL Manual directs the driver to allow pressure to build to at least 100 psi in both systems before driving. A single healthy gauge does not compensate for inadequate pressure in the other circuit.
10Which pressure pair matches the Idaho CDL Manual's usual governor operation?
A.Cut in at 20 psi; cut out at 45 psi
B.Cut in at 55 psi; cut out at 80 psi
C.Cut in at 150 psi; cut out at 175 psi after the safety valve has opened
D.Cut in at about 100 psi; cut out at about 120 to 140 psi
Explanation: The governor normally permits the compressor to resume pumping at about 100 psi and stops compressor loading around 120 to 140 psi. Applicants must also know and follow the manufacturer's specifications for the vehicle being tested.

About the Idaho CDL Air Brakes Exam

Idaho uses an air-brake knowledge test and a hands-on skills demonstration to determine whether restrictions L or Z apply. This independent English-language four-option MCQ study adaptation by OpenExamPrep focuses on Idaho process and Section 5 knowledge; it is not an official translation or test simulation and cannot replace physical air-brake inspection and skills practice.

Exam sponsor: Idaho Transportation Department Division of Motor Vehicles. The requirements and fees below concern the certification or admission exam, separate from our free practice resources.

Assessment

Applicants study Section 5 and pass the air-brake knowledge component. They must also demonstrate the required air-brake inspection and skills in an appropriately equipped vehicle to avoid or remove restriction L; testing in air-over-hydraulic equipment results in restriction Z for full air brakes.

Time Limit

ITD does not publish an Air Brakes knowledge-test time limit

Passing Score

At least 80% correct on the knowledge component; standardized practical skills scoring

Exam / Certification Fees

$5 each knowledge test; $29 CLP when required; $200 skills test; $40 four-year or $60 eight-year CDL

Exam sponsor website

Fees, eligibility, and exam policies can change. Confirm them with the exam sponsor before applying or paying.

Official sources

Our practice resources: topics covered

We aim to reflect publicly available exam outlines and topic information in our study resources. Coverage, format, and difficulty may differ from the actual exam, and we cannot guarantee that every detail is accurate or current. Confirm exam requirements, fees, and policies with the official exam sponsor.

No percentage blueprint published

Idaho Process and Restrictions

Fees, retesting, and the knowledge and skills requirements tied to restrictions L and Z.

Manual Sections 5.1 and 5.2

System Components and Dual Air

Compressor, governor, tanks, gauges, warnings, spring brakes, ABS, and the two circuits.

Manual Section 5.3 and skills chapters

Inspection

Leakage, warning, pop-out, buildup, governor, slack-adjuster, parking-brake, and service-brake checks.

Manual Section 5.4

Safe Use

Brake lag, emergency braking, fade, downgrade braking, low pressure, and parking precautions.

Preparing for the Idaho CDL Air Brakes Exam

What You Need to Know

  • Passing score: At least 80% correct on the knowledge component; standardized practical skills scoring
  • Assessment: Applicants study Section 5 and pass the air-brake knowledge component. They must also demonstrate the required air-brake inspection and skills in an appropriately equipped vehicle to avoid or remove restriction L; testing in air-over-hydraulic equipment results in restriction Z for full air brakes.
  • Time limit: ITD does not publish an Air Brakes knowledge-test time limit
  • Exam / certification fees: $5 each knowledge test; $29 CLP when required; $200 skills test; $40 four-year or $60 eight-year CDL Official sources

Using Our Practice Resources

  • Work through all 132 available questions
  • Review every answer and explanation
  • Track weak areas and revisit them
  • Use our AI tutor for tough concepts

Idaho CDL Air Brakes: Suggested Study Strategy

1Treat L and Z as restrictions, not endorsements.
2Learn the inspection sequence and verify each threshold against Section 5 and the test vehicle's manufacturer specifications.
3Practice the inspection aloud and hands-on; four-option questions cannot demonstrate the required skill.
4Use the national Air Brakes questions for shared knowledge and this Idaho supplement for state process and selected manual checks.

Frequently Asked Questions

Is Air Brakes an Idaho CDL endorsement?

No. Air-brake knowledge and skills testing determines whether restrictions L or Z appear on the CDL; it does not add an endorsement letter.

Does Idaho publish the Air Brakes knowledge-test item count?

No current item count was found in ITD's public CDL page, current manual, or current CDL process guide. OpenExamPrep therefore does not state an official count.

Can MCQ practice remove restriction L?

No. The driver must pass the required knowledge test and demonstrate air-brake inspection and driving skills in an appropriately equipped CMV.

What language is used for CDL skills testing?

Federal rules require skills-test commands and responses in English. ITD's current public pages do not provide a current CDL knowledge-test language list, so applicants should confirm availability with ITD.