Illinois CDL General Knowledge Practice Test

The Illinois CDL General Knowledge test has 50 questions. You must answer at least 40 correctly — an 80% passing score — to pass.

Illinois issues Class A (combination vehicles over 26,001 lbs GVWR with towed unit over 10,000 lbs), Class B (single vehicles over 26,001 lbs or towing a vehicle under 10,001 lbs GVWR), and Class C (transporting 16+ passengers or HazMat requiring placards). All classes require passing the General Knowledge test first.

Yes. Illinois's statewide handheld phone ban applies to all drivers including CDL holders. Additionally, federal FMCSA regulations (49 CFR 392.82) prohibit CDL operators from using handheld mobile devices while operating a commercial motor vehicle. Violations can result in CDL disqualification and civil penalties up to $2,750 per violation.

An Illinois CDL is valid for 4 years. HazMat endorsement holders must renew their TSA security threat assessment every 5 years. Your DOT medical certificate must remain current throughout your CDL validity — typically requiring a DOT physical every 24 months (or annually for certain conditions).

CDL disqualifying offenses include: DUI/OVI in any vehicle (1-year disqualification for first offense; lifetime for second), leaving the scene of an accident, using a CMV in a felony, refusing a chemical test, and driving a CMV while disqualified. In Illinois, a conviction in a personal vehicle can still disqualify your CDL.

A Class A CDL allows you to operate any combination of vehicles with a Gross Vehicle Weight Rating (GVWR) of 26,001 lbs or more, provided the towed unit exceeds 10,000 lbs — this includes tractor-trailers and double/triple trailer rigs. A Class B CDL covers single vehicles with a GVWR of 26,001 lbs or more, or any such vehicle towing a unit not exceeding 10,000 lbs — this includes straight trucks and large buses. A Class C CDL is required for vehicles designed to carry 16 or more passengers (including the driver) or for vehicles transporting hazardous materials that require placarding, when those vehicles do not qualify for Class A or B.

CDL fees vary by state and by the class and endorsements you obtain. Most states charge separate fees for the CDL knowledge test ($10–$30 per attempt), the CDL skills test ($50–$150), and the CDL license itself ($50–$100). Additional fees apply for each endorsement (HazMat, Tanker, Passenger, etc.). The HazMat endorsement also requires a TSA security threat assessment fee of approximately $86. Check your Illinois DMV website for current fee schedules.

Federal regulations (49 CFR 383.133) require that CDL applicants be able to read and speak the English language sufficiently to understand highway traffic signs and signals and to respond to official inquiries. Many states offer CDL knowledge tests in Spanish and other languages for non-commercial knowledge questions, but the actual CDL test must be taken in a language that allows the driver to meet the English proficiency requirement. Check with the Illinois DMV for available language options.

In most states, a CDL is valid for 4–8 years (commonly 4–5 years). To renew your Illinois CDL, you typically need to visit a DMV office, pass a vision test, pay the renewal fee, and update your medical certification (DOT physical). If you hold a HazMat endorsement, your TSA background check must also be current. CDLs cannot generally be renewed online due to federal requirements for in-person verification of medical certification.

If you fail the CDL General Knowledge test in Illinois, you are typically required to wait a specified period (commonly 1–7 days) before retaking it. Most states allow 2–3 attempts before requiring additional waiting periods or study requirements. There is usually a retest fee for each attempt. Focus on the areas you missed — most states provide a score sheet showing which topic areas you need to review.