Michigan CDL Air Brakes Practice Test

The Michigan CDL Air Brakes test is a multiple-choice knowledge test you take for your commercial learner's permit. Michigan Department of State (Secretary of State offices) says you need 80% to pass (source).

Last updated Oct 18, 2026. FirstTry CDL is a CDL permit test prep site by Hive Asset Group, LLC.

By Scott Wilder, Editor

Last reviewed against the Michigan CDL manual on October 18, 2026

Scott Wilder on X | scottwilderhq.com

FirstTry CDL is a CDL permit test prep site by Hive Asset Group, LLC. It offers free exam-style practice tests built from the official CDL manual. FirstTry CDL is not affiliated with any DMV, FMCSA or government agency. Practice questions are exam-style questions built from the official CDL manual, not actual test questions.

Michigan CDL permit facts

What	What Michigan says	Source
Air Brakes pass mark	80%	Official page
Air Brakes test questions	25	Official page
CLP holding period	Drive with a CLP for at least 14 days before the skills test	Official page
Knowledge test retest wait	If you fail a knowledge test, you must wait one day to retake it. There is a one day wait before any later retest too	Official page
Test languages	Michigan's CDL pages do not state the languages for CDL knowledge tests. See notes.	Official page

20 question Air Brakes practice test

1. Tank pressure falls to about 100 psi. What does the governor do?
1. A. Keeps the compressor off until 125 psi
2. B. Lets the compressor start pumping again
3. C. Opens the safety valve
4. D. Applies the spring brakes
Show answer
Answer: B. Lets the compressor start pumping again
At the cut-in pressure of around 100 psi, the governor lets the compressor pump again.
From the official CDL manual, section 5.1.2.
2. Which statement about wedge brakes is true?
1. A. They may be self-adjusting or need manual adjustment
2. B. They never need adjustment
3. C. They must always be adjusted by hand
4. D. They are the most common type
Show answer
Answer: A. They may be self-adjusting or need manual adjustment
Wedge type brakes may be self-adjusting or may require manual adjustment.
From the official CDL manual, section 5.1.8.
3. Your vehicle has no automatic air tank drains. Why must you drain the tanks at the end of each working day?
1. A. To lower pressure so the governor cuts in sooner
2. B. To keep the tanks from overfilling above 125 psi
3. C. To keep the spring brakes from coming on overnight
4. D. To remove moisture and oil, or the brakes could fail
Show answer
Answer: D. To remove moisture and oil, or the brakes could fail
Draining removes moisture and oil from the tanks; otherwise the brakes could fail.
From the official CDL manual, section 5.4.8.
4. In the proper low gear on a downgrade, how hard should you apply the brakes?
1. A. Just hard enough to feel a definite slowdown
2. B. As hard as you can without locking the wheels
3. C. As lightly as possible, and keep them applied all the way down
4. D. Only enough to turn on the brake lights
Show answer
Answer: A. Just hard enough to feel a definite slowdown
The proper technique is to apply the brakes just hard enough to feel a definite slowdown.
From the official CDL manual, section 5.4.6.
5. As you fan off pressure on a straight truck, what should the parking brake valve do at the specified pressure?
1. A. Close and pop out, so the spring brakes come on
2. B. Stay pushed in until pressure reaches zero
3. C. Pop out at about 100 psi
4. D. Push in harder to hold the brakes off
Show answer
Answer: A. Close and pop out, so the spring brakes come on
When pressure falls to the manufacturer's specification, the parking brake valve should pop out and apply the spring brakes.
From the official CDL manual, section 5.3.3.
6. You are making a normal stop with air brakes. How should you use the brake pedal?
1. A. Push it down and control the pressure for a smooth stop
2. B. Pump it many times quickly
3. C. Push it to the floor and hold it
4. D. Tap it once and coast
Show answer
Answer: A. Push it down and control the pressure for a smooth stop
You push the pedal down and control the pressure. This gives a smooth, safe stop.
From the official CDL manual, section 5.4.1.
7. When may a driver fully apply the brakes in an emergency stop with ABS?
1. A. Whenever only the tractor has ABS
2. B. Whenever only the trailer has ABS
3. C. Whenever the road is dry
4. D. When driving a straight truck or combination with working ABS on all axles
Show answer
Answer: D. When driving a straight truck or combination with working ABS on all axles
The one exception is a driver who always drives vehicles with working ABS on all axles, who can fully apply the brakes in an emergency stop.
From the official CDL manual, section 5.4.2.
8. A truck has ABS on only one axle. What does the manual say about that?
1. A. It is not allowed
2. B. It still gives you more control while braking
3. C. It gives no benefit
4. D. It makes the brakes grab
Show answer
Answer: B. It still gives you more control while braking
The manual says even one ABS axle gives more control during braking.
From the official CDL manual, section 5.4.2.
9. What can ABS help you do in a hard stop?
1. A. Steer around an obstacle while braking
2. B. Always stop in a shorter distance
3. C. Follow closer to the vehicle ahead
4. D. Skip the use of engine braking on grades
Show answer
Answer: A. Steer around an obstacle while braking
With ABS you may or may not stop faster, but you should be able to steer around an obstacle while braking.
From the official CDL manual, section 5.4.2.
10. Which vehicles may have a front brake limiting valve control in the cab?
1. A. Some older vehicles made before 1975
2. B. All vehicles made after 1997
3. C. Only buses that carry passengers
4. D. Only trailers pulled by tractors
Show answer
Answer: A. Some older vehicles made before 1975
Some vehicles made before 1975 have the cab control marked normal and slippery.
From the official CDL manual, section 5.1.13.
11. On an older ABS system, how long might the malfunction lamp stay on after start-up?
1. A. Until you are driving over 25 mph
2. B. Until you are driving over five mph
3. C. Until the engine is off
4. D. Until the tanks reach 125 psi
Show answer
Answer: B. Until you are driving over five mph
On older systems, the lamp could stay on until you are driving over five mph.
From the official CDL manual, section 5.1.16.
12. Which is another name for the brake pedal in an air brake system?
1. A. Relay valve
2. B. Check valve
3. C. Treadle valve
4. D. Modulating valve
Show answer
Answer: C. Treadle valve
The brake pedal is also called the foot valve or treadle valve.
From the official CDL manual, section 5.1.7.
13. A vehicle without ABS brakes hard on a slick road and the non-steering wheels lock. What can happen?
1. A. The vehicle will always stop in a straight line
2. B. The brakes will cool down faster
3. C. The vehicle may skid, jackknife, or spin
4. D. Nothing, because only steering wheels matter
Show answer
Answer: C. The vehicle may skid, jackknife, or spin
Locked wheels other than the steering wheels can cause a skid, a jackknife, or a spin.
From the official CDL manual, section 5.4.2.
14. Why is manual adjustment of an automatic slack adjuster dangerous?
1. A. It voids the vehicle's registration
2. B. It always makes the brakes lock up
3. C. It can give a false sense of security about the brakes
4. D. It makes the air tanks leak
Show answer
Answer: C. It can give a false sense of security about the brakes
The manual says it may give the driver a false sense of security.
From the official CDL manual, section 5.3.2.
15. What does the emergency brake system use to stop the vehicle when a brake system fails?
1. A. A separate set of brakes used only in emergencies
2. B. Parts of the service and parking brake systems
3. C. Only the parking brake system
4. D. Only the trailer brakes
Show answer
Answer: B. Parts of the service and parking brake systems
The emergency system shares parts of the service and parking brake systems.
From the official CDL manual, section 5.
16. Which type of foundation brake is the most common?
1. A. The s-cam drum brake
2. B. The wedge brake
3. C. The air disc brake
4. D. The hydraulic drum brake
Show answer
Answer: A. The s-cam drum brake
The s-cam drum brake is the most common foundation brake.
From the official CDL manual, section 5.1.8.
17. How do you put the parking brakes on with the push-pull knob?
1. A. Push the knob in
2. B. Turn the knob a quarter turn
3. C. Pull the knob out
4. D. Hold the knob in and press the pedal
Show answer
Answer: C. Pull the knob out
Pulling the knob out puts the spring brakes on, and pushing it in releases them.
From the official CDL manual, section 5.1.15.
18. What does the air compressor governor control?
1. A. How hard the brake shoes press on the drum
2. B. When the spring brakes release
3. C. How much alcohol enters the system
4. D. When the compressor pumps air into the tanks
Show answer
Answer: D. When the compressor pumps air into the tanks
The governor decides when the compressor pumps air and when it stops.
From the official CDL manual, section 5.1.2.
19. In an s-cam brake, air pressure in the brake chamber pushes out the rod. What does the rod move next?
1. A. The wedge
2. B. The slack adjuster
3. C. The power screw
4. D. The brake drum
Show answer
Answer: B. The slack adjuster
The rod moves the slack adjuster, which twists the brake camshaft.
From the official CDL manual, section 5.1.8.
20. Why is slow air pressure buildup a danger?
1. A. The horn may stop working
2. B. The tires may go flat
3. C. The engine may overheat
4. D. Pressure may drop too low while driving, and you may need an emergency stop
Show answer
Answer: D. Pressure may drop too low while driving, and you may need an emergency stop
The manual says slow buildup may let pressure drop too low during driving.
From the official CDL manual, section 5.3.3.

Michigan CDL Air Brakes questions

What score do you need to pass the Michigan CDL Air Brakes test?

Michigan says you need 80% to pass the Air Brakes test.

Is the Michigan CDL Air Brakes test the same as other states?

The Air Brakes test is built on the same federal knowledge standards in every state, so the topics match the CDL manual. Michigan uses its own handbook: https://www.michigan.gov/sos/-/media/Project/Websites/sos/Resources/Forms-and-publications/CDL-Manual/cdlmanual.pdf

What languages is the Michigan CDL knowledge test offered in?

Michigan's CDL pages do not state the languages for CDL knowledge tests. See notes.

Sources

https://www.michigan.gov/sos/all-services/cdl-apply
https://www.michigan.gov/sos/-/media/Project/Websites/sos/Resources/Forms-and-publications/CDL-Manual/cdlmanual.pdf
Manual sections used in this test: 5; 5.1.13; 5.1.15; 5.1.16; 5.1.2; 5.1.7; 5.1.8; 5.3.2; 5.3.3; 5.4.1; 5.4.2; 5.4.6; 5.4.8

Air Brakes practice test in nearby states