Illinois Air brakes practice test
Air brakes is not an endorsement — it is a restriction you avoid. Skip this test, or take your Illinois skills test in a vehicle without air brakes, and the SOS prints an L restriction on your CDL barring you from air-braked vehicles. Nearly every real truck has them.
On a long downgrade, the application pressure gauge shows you need steadily MORE pressure to hold the same speed. This means:
Air brakes and the L restriction in Illinois
Two things have to happen before Illinois will let you drive an air-braked vehicle: you pass the air brakes knowledge test, and you take your skills test in a vehicle that actually has a full air brake system. Do only the first and the restriction still goes on the licence.
That makes the truck you borrow for the SOS skills test a licensing decision, not a logistics one. Removing an L later means passing the knowledge test again and retaking the skills test in the right vehicle — cheaper to get it right the first time.
Fees, scheduling and document requirements are set by Illinois. Confirm the current details with the SOS before you go.
What the air brakes test covers
The questions come from the federal CDL manual, so the material is the same in Illinois as it is anywhere else. The full breakdown — what each section asks and the figures worth memorising — is on the air brakes practice test guide. Everything on this page is the IL half of it.
Before any endorsement there is the written test everyone takes. The Illinois general knowledge practice test covers it, and the Illinois DOT physical page covers the medical certificate you cannot be licensed without.
Frequently asked
- Is air brakes an endorsement in Illinois?
- No, and it works in reverse. Every Illinois driver is assumed to need air brakes; failing to test on them adds an L restriction to the CDL rather than leaving an endorsement off it.
- How do I remove an L restriction in Illinois?
- Pass the air brakes knowledge test and retake the skills test in a vehicle with a full air brake system. The SOS then reissues the licence without the restriction.