Class A CDL Pre-Trip Inspection Checklist: What You Need to Know

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The pre-trip inspection is one of the most detailed and commonly failed portions of the CDL skills test.

Let’s address the chief question that many students ask:

What Is Included in a Class A CDL Pre-Trip Inspection?

A Class A CDL pre-trip inspection includes a systematic safety check of the engine compartment, cab controls, brake systems, suspension, steering components, coupling system, and trailer to ensure the vehicle is safe to operate.

Examiners are not just looking for you to point at parts. The examiners expect you to identify components, explain what you’re checking, and state what defects you’re looking for.

Below is a simplified, structured checklist to help you prepare.

Engine Compartment Checklist (Front of Tractor)

When inspecting the engine area, you must identify components and explain that they are:

  • Securely mounted
  • Not cracked, bent, or broken
  • Not leaking (fluids or air)

Key Engine Components to Check:

  • Oil level (proper level, no leaks)
  • Coolant level (secure cap, proper level)
  • Power steering fluid (proper level)
  • Alternator (secure, no frayed wires)
  • Water pump (not leaking)
  • Air compressor (secure, no leaks)
  • Belts (no cracks, frays, excessive slack — no more than ¾ inch play)
  • Hoses (no leaks, abrasions, bulges)
  • Steering shaft (not bent, secure)
  • Steering gearbox (no leaks, securely mounted)

This section establishes your ability to identify safety-critical mechanical systems.

We recognize that this may be daunting at first. If you’re preparing for your CDL training, review Our Programs for additional support.

In-Cab Inspection Checklist

This portion tests your knowledge of brake systems, gauges, and safety equipment.

Cab Safety Equipment:

  • Seat belt (secure, not frayed)
  • Fire extinguisher (fully charged, properly mounted)
  • Spare fuses (if required)
  • Reflective triangles (three required)

Gauges & Warning Lights:

  • Oil pressure gauge (rises to normal range)
  • Voltmeter (proper charging range)
  • Coolant temperature gauge (rises gradually)
  • Air pressure gauges (build to governor cut-out 120–140 PSI)

Air Brake Test (Must Be Performed in Order):

  • Applied pressure test (3 PSI single / 4 PSI combination max loss)
  • Low air warning activates before 60 PSI
  • Spring brakes pop out between 20–40 PSI

If you need a refresher on the air brake procedure, review our simplified guide.

Coupling System Checklist (For Class A Combination Vehicles)

Because Class A vehicles pull trailers, coupling inspection is critical.

Fifth Wheel Area:

  • Skid plate (properly greased)
  • Locking jaws (fully locked around kingpin)
  • Release arm (secure, locked in place)
  • Mounting bolts (tight, not missing)

Air & Electrical Lines:

  • No cuts, cracks, or abrasions
  • Properly connected and secured
  • No air leaks

Kingpin & Apron:

  • Kingpin not bent
  • Apron not cracked
  • Gap between tractor and trailer is correct

Failure in this section can result in an automatic test failure.

For more information about Class A requirements, read Here.

Trailer Inspection Checklist

You must inspect the trailer just as thoroughly as the tractor.

Trailer Exterior:

  • Landing gear (fully raised, secure)
  • Frame (no cracks, bends, breaks)
  • Suspension components (leaf springs, shocks, U-bolts secure)
  • Brake chambers (not leaking, properly mounted)
  • Slack adjusters (no more than 1 inch play with brakes released)
  • Brake hoses (no cuts or leaks)

Tires & Wheels:

  • Proper tread depth (minimum 2/32 steer, 1/32 others depending on state standards)
  • No cuts or bulges
  • Rims not bent or cracked
  • Lug nuts tight, no rust trails

Lights & Reflectors:

  • Clearance lights
  • Brake lights
  • Turn signals
  • Reflectors clean and functional

Why the Pre-Trip Inspection Is So Important

The CDL pre-trip inspection proves that you understand:

  • Vehicle safety
  • Mechanical awareness
  • Federal compliance standards

Commercial vehicles operate under strict federal oversight through the FMCSA. Proper inspection reduces breakdowns, accidents, and violations.

You can review Federal Inspection Guidelines on the FMCSA Site. 

How to Pass the Pre-Trip Inspection

Success comes down to:

  • Practicing your verbal explanation
  • Following a consistent order
  • Touching and identifying each component
  • Stating what you’re checking for
  • Staying calm and confident

The pre-trip inspection is all about memorization plus repetition.

And in a grand summary, a Class A CDL pre-trip inspection includes:

  • Engine compartment checks
  • In-cab brake and safety tests
  • Coupling system inspection
  • Full trailer walk-around

Mastering this checklist dramatically increases your chance of passing on the first attempt.

If you want structured hands-on training before your exam, Contact Progressive Truck Driving School today!

The Air Brakes Test Simplified: How to Pass the CDL Air Brakes Test in 2026

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Air brakes are one of the most important systems on a commercial vehicle. They are also one of the most commonly failed portions of the CDL exam.

So let’s address what many students are asking:

How Do You Pass the CDL Air Brakes Test?

To pass the CDL air brakes test, you must understand air brake components, explain the system correctly during your pre-trip inspection, and perform the 3-step air brake check procedure without missing critical pressure loss or warning thresholds.

The good news? Once you understand the structure, it’s straightforward.

Below is a simplified cheat sheet breakdown to help you remember exactly what examiners look for.

The 3-Step Air Brake Check Cheat Sheet

During your CDL pre-trip inspection, you must perform the air brake test in order and explain each step clearly. Let’s explore each step in detail:

Step 1: Applied Pressure Test (Leak Test)

Purpose: Check for excessive air loss.

What to do:

  1. Build air pressure to the governor cut-out (typically 120–140 PSI).
  2. Turn the engine off.
  3. Release (push in) both parking brakes.
  4. Fully apply and hold the service brake for one minute.

What the examiner wants to hear:

  • For combination vehicles: No more than 4 PSI air loss in one minute.
  • For single vehicles: No more than 3 PSI air loss in one minute.

If pressure drops too fast, you fail.

Step 2: Low Air Warning Device Test

Purpose: Ensure the warning system activates properly.

What to do:

  1. With the engine still off, pump the brake pedal repeatedly.
  2. Continue reducing air pressure.

What the examiner wants to hear:

  • Low air warning light and/or buzzer must activate before 60 PSI.

If it doesn’t activate, the vehicle is unsafe and it’s an automatic failure.

Step 3: Emergency Spring Brake Pop-Out Test

Purpose: Confirm the parking brake system activates automatically.

What to do:

  1. Continue pumping the brakes.
  2. Watch for the parking brake knobs to pop out automatically.

What the examiner wants to hear:

  • Parking brakes must engage between 20–40 PSI.

If they don’t pop out within that range, you fail.

Why the Air Brakes Test Matters

Air brakes operate differently from hydraulic systems used in passenger vehicles. Commercial vehicles rely on compressed air to safely stop large loads.

Because of the safety risk, this portion of the CDL test is strict. Missing PSI thresholds or performing steps out of order can result in an automatic failure.

If you’re preparing for your CDL exam, make sure your training program emphasizes hands-on air brake testing. Learn more about our CDL training programs.

Common Air Brake Test Mistakes

Students often fail because they:

  • Forget to release parking brakes during the leak test
  • Don’t hold the brake pedal for the full one minute
  • Don’t state PSI limits out loud
  • Rush through steps without explaining them clearly
  • Confuse single vehicle vs. combination PSI standards

Practicing the verbal explanation is just as important as performing the test correctly.

Do You Need an Air Brakes Endorsement?

Air brakes are not technically an “endorsement” but they can be a restriction.

If you fail or skip the air brakes test, you receive an “L restriction” on your CDL, meaning you cannot operate vehicles with air brakes.

Since most Class A combination vehicles use air brakes, passing this test is critical for maximum job flexibility.

If you’re deciding which CDL path is right for you, review the difference between Class A and Class B.

Bonus Tip: Practice the Script

Examiners grade consistency and confidence.

Memorize this simplified structure:

  1. Applied pressure test- no more than 3 PSI (single) or 4 PSI (combination) in one minute.
  2. Low air warning must activate before 60 PSI.
  3. Spring brakes must pop out between 20–40 PSI.

If you can clearly state those three pressure benchmarks, you dramatically increase your chance of passing.

Summary

Passing the CDL air brakes test comes down to:

  • Performing steps in order
  • Knowing the PSI limits
  • Explaining what you’re doing
  • Staying calm and deliberate

With proper training and repetition, the air brake check becomes routine.

If you’re preparing for your CDL exam or want structured, hands-on practice, Contact Progressive Truck Driving School today!