Pass the Illinois CDL Written Exam
219+ practice questions covering all CDL classes and endorsements.
General Knowledge, Air Brakes, Combination, Doubles/Triples, Tank, HazMat, Passenger & School Bus.
What CDL Are You Studying For?
Select your target license class to see which test sections you need.
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DMV Practice Exams
Each exam simulates the real DMV test for that section — same number of questions, timed, 80% to pass.
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This site is not affiliated with or endorsed by the State of Illinois or the Secretary of State's office. It is an independent study tool based on publicly available materials.
Illinois CDL — Exam Facts & Guide
What is a CDL?
A Commercial Driver's License (CDL) is required to operate large or specialized commercial motor vehicles (CMVs) in the United States. Illinois issues CDLs through the Secretary of State's office.
CDL License Classes
| Class | Vehicle Type | Written Tests Required |
|---|---|---|
| Class A | Combination vehicles with GCWR 26,001+ lbs (towed vehicle > 10,000 lbs) | General Knowledge + Air Brakes + Combination Vehicles |
| Class B | Single vehicles with GVWR 26,001+ lbs | General Knowledge + Air Brakes |
| Class C | Vehicles transporting 16+ passengers or HazMat (under 26,001 lbs) | General Knowledge + Endorsement test(s) |
CDL Endorsements
| Code | Endorsement | Required For |
|---|---|---|
| T | Doubles/Triples | Pulling double or triple trailers |
| N | Tank Vehicle | Tank vehicles with capacity > 119 gallons |
| H | Hazardous Materials | Placarded hazardous materials + TSA background check |
| X | HazMat + Tank | Combination of H and N endorsements |
| P | Passenger | Vehicles designed to carry 16+ passengers |
| S | School Bus | School bus operation + requires P endorsement |
The Written Exam
- General Knowledge: 50 questions — required for all CDL classes
- Air Brakes: 25 questions — required for Class A and B
- Combination Vehicles: 20 questions — required for Class A
- Endorsement tests: 20-30 questions each
- You need 80% to pass each test section
- Must be at least 21 years old for interstate commerce (18 for intrastate only)
Disqualifying Offenses
- DUI with BAC 0.04% or higher while operating a CMV
- First DUI: 1-year disqualification (3 years if hauling HazMat)
- Second DUI: Lifetime disqualification
- Using a handheld phone while driving a CMV is a serious violation
- Leaving the scene of an accident: 1-year minimum disqualification
Study Tips
- Start with General Knowledge — it's the foundation for all CDL tests
- Use the "Build Your Study Path" on the home page to focus on your specific CDL class
- Review wrong answers carefully — explanations cite the exact rule
- Take multiple practice exams until you consistently score 90%+
- Pay special attention to numbers: distances, pressures, weights, and time limits