Fail this Go Home!
Forget this during the air brake check and your CDL test is over before it starts.
What is failing to explain and perform all four parts of the air brake check?
Normal governor cut-out pressure lives in this neighborhood.
What is 120–140 PSI?
This indicator proves your high beams are actually high.
What is the high-beam indicator light?
The windshield must be clean and free of obstructions except for this one thing.
What is an inspection sticker?
Minimum tread depth on steering axle tires is this many thirty-seconds of an inch.
What is 4/32?
If air pressure drops more than this in one minute on a combination vehicle, something’s leaking—and so is your score.
What is 4 PSI?
The low air warning devices must activate before pressure drops below this number (unless the manufacturer says otherwise).
What is 55 PSI? (55 PSI and Above)
This dashboard system warns of braking issues—not engine problems.
What is the ABS system?
Cracks, stickers, or dirt here can cause you to miss traffic changes.
What is the driver’s viewing area?
All other tires only need this much tread depth to be legal.
What is 2/32?
Kicking tires instead of using this tool earns you exactly zero credit.
What is a tire pressure gauge?
These valves should pop out between 20 and 45 PSI during the emergency brake test.
What are the Parking Brake and Tractor Protection brake valves?
This system includes DEF and DPF warnings and exists to keep the EPA happy.
What is the emissions system?
Mirrors must be clean, adjusted, and mounted securely—especially these parts.
What are the mirror brackets?
Rust trails or shiny threads usually mean this bad thing.
What are loose lug nuts?
This light must turn on and then off during startup, or the examiner’s eyebrow goes up.
What is the ABS indicator light?
If your vehicle has a backup air system, this may not happen—and you better explain why.
What is the brake valve popping out?
You check that these indicators work on startup—but test the actual lights later outside.
What are turn signals and four-way flashers?
These devices must be viewable from inside the cab if installed.
What are monitoring cameras or video displays?
These cannot be welded—ever.
What are rims?
Removing this while the engine is hot is a great way to fail and get burned.
What is the coolant radiator cap?
On air-operated trailers, this valve should pop out at the same time or before the tractor valve.
What is the tractor protection valve?
If this light stays on after startup, you’d better say something.
What is the ABS warning light?
If mirrors or cameras are dirty, the examiner assumes this: you didn’t inspect them.
What is they are not safe to use?
Bumps or bulges here scream “blowout waiting to happen.”
What is the tire sidewall?