CDL in-cab inspection and air brake check: what to say
- Governor cut-out: 120–140 psi.
- Leakage, engine off, brake held one minute: no more than 4 psi on a combination, 3 psi on a single vehicle.
- Low air warning before 55 psi (60 in New York and North Carolina’s skills test).
- Spring brakes pop out between 20–45 psi.
Why the air brake check matters so much
The state manuals we checked all treat it as all-or-nothing. Older manuals split it into three parts (leakage, low air warning, spring brakes); the modernized manual adds building air to governor cut-out as a fourth. Delaware’s puts it plainly: failing to explain and perform all four parts correctly is an automatic failure.
You have to do it and say it. Watching the gauge silently earns nothing: say each number out loud as you see it.
The air brake check, step by step
What to say
- “Wheels are chocked. I start the engine.”
- “Air builds to governor cut-out, 120 to 140 psi.”
- “Engine off, key on.”
- “I release the parking brake and trailer air.”
- “I hold the brake pedal down for one minute.”
- “It loses no more than four psi in that minute.”
- “I fan the brakes. Low air warning before 55 psi.”
- “I keep fanning, and the valves pop out.”
- “They pop between 20 and 45 psi.”
What the examiner listens for
- Builds air to governor cut-out and says the value
- Leakage test done right
- Low air warning before the limit
- Spring brake valves pop in range
Every in-cab item on the checklist
9 items. What to point at and what the examiner expects you to say about each.
| Item | What to check |
|---|---|
| Air brake checkauto fail | Builds air to governor cut-out and says the value · Leakage test done right · Low air warning before the limit · Spring brake valves pop in range Script and video |
| Parking & trailer brake check | Parking brake holds · Trailer brake holds Script in the app |
| Service brake check | Pulls forward at about 5 mph · Applies the foot brake to stop · Doesn't pull to either side Script in the app |
| Lighting indicators | Left and right turn indicators · Four-way flasher indicator · High beam indicator · ABS light comes on then goes off Script in the app |
| Emergency equipment | Three red reflective triangles · Fire extinguisher charged and secured · Spare fuses or circuit breakers Script in the app |
| Windshield & traffic monitoring devices | Windshield clean, not cracked · Nothing blocking the view · Mirrors clean and adjusted Script in the app |
| Wipers & washers | Arms and blades secure, not damaged · Wipers operate smoothly · Washers work Script in the app |
| Heater & defroster | Heater works · Defroster works Script in the app |
| Horn(s) | Horns work Script in the app |
When your state’s numbers differ
The figures above are the national model’s. Most states use them; a few do not. On the pre-trip, New York and North Carolina expect the low air warning before 60 psi. California’s handbook gives its own leakage limits and says failing to say the test parameters is an automatic failure of the inspection. Go by your state’s manual: every state’s numbers and rules are on its CDL manual page.
The air brakes knowledge test asks about a different leakage check (static, brakes released), with lower limits, and some state manuals give a different low air figure in the air brakes chapter (60 psi in Washington, for example). See the air brakes test guide.
Mr. Egg's 32 short video lessons cover the whole walk-around with the exact words for each item. Record yourself saying it back, then run a timed mock inspection scored by an AI examiner.
Get all the scripts in the appSee the whole walk-around: all 32 items on the CDL pre-trip checklist.