Illinois CDL Knowledge Test Sample Questions
Real, Illinois-specific sample questions from our practice question bank, with the correct answer, a full explanation, and a source reference for each. See our national sample questions for topics that apply to every state, or take the full Illinois cdl practice test to test yourself instead of just reading the answers.
More Questions
1. What happens when air pressure in an air brake system drops below a safe level?
When air pressure drops too low, spring brakes apply automatically to prevent a runaway vehicle.
Source: Illinois SOS, Commercial Driver's License Manual, Air Brakes
2. If the drive wheels begin to skid from over-acceleration on a wet road, what should the driver do?
Easing off the accelerator lets the drive wheels regain traction; braking hard or steering sharply can make the skid worse.
Source: Illinois SOS, Commercial Driver's License Manual, Skid Control
3. Under federal hours-of-service rules, how many hours may a property-carrying driver typically drive after 10 hours off duty?
Federal rules allow most property-carrying drivers up to 11 hours of driving time after 10 consecutive hours off duty.
Source: Illinois SOS, Commercial Driver's License Manual, Hours of Service
4. At a railroad crossing where a stop is required, how far from the nearest rail should a commercial vehicle stop?
A commercial vehicle required to stop should stop no closer than 15 feet and no farther than 50 feet from the nearest rail.
Source: Illinois SOS, Commercial Driver's License Manual, Railroad Crossings
5. What is the main purpose of a pre-trip inspection for a commercial vehicle?
A pre-trip inspection is meant to catch mechanical problems before they cause a breakdown or crash on the road.
Source: Illinois SOS, Commercial Driver's License Manual, Vehicle Inspection