Illinois Air Brakes Test
From the Stevenson Expressway to the Dan Ryan, this test covers what you need to know for Illinois roads — including how lake-effect snow and winter salt affect your air brake system.
Select Test Mode
This is the Illinois Air Brakes practice test — 25 questions, 30 minutes. It's the exact same format as the real test at the Secretary of State.
Key Topics
- •System components and governor operation
- •Dual air systems and failure scenarios
- •Brake lag, stopping distances, and winter conditions
About the Illinois Air Brakes Test
Topics Covered
- ✓Air brake system components — you need to identify the compressor, reservoirs, brake chambers, and slack adjusters. Illinois examiners love asking about the governor cut-in and cut-out pressures (100 psi and 120 psi).
- ✓Brake lag — critical on I-55 where you need to anticipate stopping distances in heavy traffic. Illinois winters make it worse with wet or icy pavement.
- ✓Dual air brake systems — Illinois requires both systems functioning during the pre-trip inspection. One fails, you're out of service.
- + 3 more topics
📘 Study Tips & State Info
Illinois DMV examiners focus on the pre-trip inspection sequence for air brakes. They want you to name each component and explain what it does. Practice saying it out loud: 'This is the air compressor. It pumps air into the reservoirs. The governor controls when it cuts in and cuts out.' Don't skip the low-pressure warning check — they'll ask what happens below 60 psi.
Pay extra attention to the section about driving in cold weather. Illinois has real winters. The test might ask about alcohol evaporators, air dryers, and how to keep your air system from freezing. Know the difference between an alcohol evaporator and an air dryer — they're not the same thing.
One last thing: Illinois uses the federal standards, but the written test often includes a question about what to do if your low-pressure warning comes on while driving. The answer is always 'stop immediately and safely.' Don't try to nurse it to the next exit.
The Illinois Secretary of State handles all CDL testing. You'll take the Air Brakes test at one of their facilities — popular ones include Chicago South (5301 W. 31st St.), Schaumburg (700 E. Golf Rd.), and Springfield (2701 S. Dirksen Pkwy.). Appointments are strongly recommended and can be booked online. Walk-ins are accepted but you might wait hours.
The written test fee is $60, which covers the General Knowledge test plus up to five endorsement tests (including Air Brakes). You pay once per visit. If you fail the Air Brakes test, you can retake it the next business day, but you'll pay the $60 fee again. Bring your valid Medical Examiner's Certificate (DOT physical) and proof of Illinois residency.
Illinois also requires a pre-trip inspection during the skills test that includes a full air brake inspection. You'll check for air leaks, test the low-pressure warning, and verify the spring brakes activate at the right pressure. Practice this with a real truck if you can — the examiners watch closely.
About the Illinois Air Brakes Test
If you're driving a commercial vehicle in Illinois with air brakes, you need this endorsement. Period. The Illinois Air Brakes test covers everything from compressor cut-out pressures to what happens when your low-pressure warning light comes on in a snowstorm on I-57.
Illinois roads aren't forgiving. You've got the Stevenson Expressway (I-55) with its tight merges and constant braking. You've got I-80 through Joliet with heavy truck traffic and winter ice. And you've got the Dan Ryan (I-94) where stop-and-go traffic can cook your brakes if you don't understand brake lag and proper following distance. The test makes sure you know how air brakes work before you get behind the wheel.
The test has 25 multiple-choice questions. You need 80% to pass — that's 20 out of 25. You'll take it at any Illinois Secretary of State CDL testing facility. Most people finish in 20–25 minutes, but you get the full 30.
Don't just memorize the answers. Learn the system. Your air brakes are the only thing between you and a ditch on I-55. Know them.
Topics Covered
Study Tips
Illinois DMV examiners focus on the pre-trip inspection sequence for air brakes. They want you to name each component and explain what it does. Practice saying it out loud: 'This is the air compressor. It pumps air into the reservoirs. The governor controls when it cuts in and cuts out.' Don't skip the low-pressure warning check — they'll ask what happens below 60 psi.
Pay extra attention to the section about driving in cold weather. Illinois has real winters. The test might ask about alcohol evaporators, air dryers, and how to keep your air system from freezing. Know the difference between an alcohol evaporator and an air dryer — they're not the same thing.
One last thing: Illinois uses the federal standards, but the written test often includes a question about what to do if your low-pressure warning comes on while driving. The answer is always 'stop immediately and safely.' Don't try to nurse it to the next exit.
Illinois Specific Information
The Illinois Secretary of State handles all CDL testing. You'll take the Air Brakes test at one of their facilities — popular ones include Chicago South (5301 W. 31st St.), Schaumburg (700 E. Golf Rd.), and Springfield (2701 S. Dirksen Pkwy.). Appointments are strongly recommended and can be booked online. Walk-ins are accepted but you might wait hours.
The written test fee is $60, which covers the General Knowledge test plus up to five endorsement tests (including Air Brakes). You pay once per visit. If you fail the Air Brakes test, you can retake it the next business day, but you'll pay the $60 fee again. Bring your valid Medical Examiner's Certificate (DOT physical) and proof of Illinois residency.
Illinois also requires a pre-trip inspection during the skills test that includes a full air brake inspection. You'll check for air leaks, test the low-pressure warning, and verify the spring brakes activate at the right pressure. Practice this with a real truck if you can — the examiners watch closely.