Illinois CDL knowledge test: what is different
Illinois gives a shorter General Knowledge test than most states: 30 questions instead of the usual 50. It also has a Charter Bus endorsement test, and the School Bus test needs 90%.
Illinois test facts
| Fact | Illinois | Source | Checked |
|---|---|---|---|
| General Knowledge test | 30 questions; pass with 24 right (80%) | Illinois Secretary of State, CDL page | 2026-10-29 |
| Other knowledge tests | Air Brakes 25, Combination 20, Passenger 20, Tank 20, Doubles/Triples 20, School Bus 20, HazMat 30, Charter Bus 20 | Illinois CDL Study Guide (DSD CDL 10.30, July 2025), Section 1 | 2026-10-25 |
| Pass mark | 80% on each test; School Bus needs 90% | Illinois Secretary of State, CDL page | 2026-10-29 |
| Language | English only. An audio version is available on request | Illinois Secretary of State, CDL page | 2026-10-29 |
| Study guide | DSD CDL 10.30, July 2025. The Spanish edition is older (September 2023) | Illinois Secretary of State publications | 2026-10-24 |
| Illinois-only test | Charter Bus (C) endorsement, 20 questions | Illinois CDL Study Guide, Section 1 | 2026-10-25 |
What Examlane does for Illinois
- When you choose Illinois, the General Knowledge mock test has 30 questions and needs 24 right, and the School Bus mock needs 90%.
- Examlane has no Charter Bus pack yet.
Practice and choose Illinois when asked.
Changes
- 2026-10-24: test lengths and pass marks checked against the Illinois CDL page and the July 2025 study guide.
- 2026-10-29: the Illinois CDL page read again: the same test length, pass marks and language.
Checked by the Examlane team. If Illinois's own site differs, it wins; tell us at [email protected].