CDL Class B Bus Inspection Exam Checklist (Study Guide)

Passing the CDL Class B bus inspection exam requires memorizing a specific 30+ point inspection sequence. The examiner watches for three things: that you touch or point to every component, that you say the correct defect criteria, and that you follow the exact order shown in the FMCSA pre-trip inspection framework. This checklist covers every item you need to inspect on a school bus or transit bus during the CDL skills test. Practice this sequence until it becomes automatic. The exam is not about mechanical knowledge—it is about completing a standardized routine without skipping steps. Schedule a demo of Bus CMMS digital inspection training tools.

CDL Study Guide

CDL Class B Bus Inspection Exam Checklist

Memorize this 30+ point inspection sequence. Pass your pre-trip exam on the first attempt.

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Engine Compartment Inspection

Check these items under the hood (front engine) or at rear engine access panel.

Engine oil level — between add and full marks, amber to light brown color Coolant level — between min/max lines, no oil sheen or floating debris Power steering fluid — within operating range, no foaming or burnt smell Windshield washer fluid — reservoir at least half full Serpentine/drive belts — no cracks, fraying, glazing, or missing ribs Radiator & heater hoses — no bulges, soft spots, cracks, or leaks Alternator mounting — brackets secure, wires connected with no corrosion Air compressor (air brake buses) — no oil/coolant leaks, lines secure

In-Cab & Instrument Check

Sit in driver seat. Complete before starting engine, then during startup.

Steering wheel — no excessive play (max 2 inches), tilt mechanism locks Horn — audible, works in all positions Windshield wipers — all speeds work, park correctly, washer sprays Heater & defroster — fan speeds work, air directs to windshield vents Mirrors — cross-view, convex, flat mirrors secure, no cracks, you can adjust them Seat belt — retracts, latches firmly, no fraying or cuts in webbing Warning lights — key ON position, engine not started. Check engine, ABS, stop engine lights illuminate Oil pressure gauge — after start, pressure rises within 10 seconds (20-60 PSI normal) Voltmeter — voltage between 13.5 and 14.5 volts after start Air pressure gauge (air brakes) — pressure builds, primary/secondary rise together Emergency equipment — fire extinguisher charged (green zone), 3 reflective triangles present

Exterior Walk-Around — Front of Bus

Start at driver side front. Touch or point within 6 inches of each component.

Bumper — no cracks, dents, or loose mounts Grille — no missing pieces, secure to body Headlights — clean lenses, both low beam and high beam function Turn signals — amber lenses, front and side markers flash at correct rate Windshield — no chips larger than 1/4 inch in driver line of sight Hood (front engine) — latches secure, no misalignment, safety catch works

Exterior Walk-Around — Driver Side

Tires — tread depth: steer axle 4/32 inch minimum, drive axle 2/32 inch minimum Sidewalls — no bulges, cuts exposing cords, weather checking deeper than 1/16 inch Wheels & rims — no cracks, no rust jacking, all lug nuts present and tight Leaf springs / air bags — no cracks in springs, air bags not rotted or leaning Shock absorbers — no leaks, mounts tight, not bent Exhaust system — no leaks, hangers intact, pipe extends past passenger door Fuel tank — cap secure, no leaks, no damage to tank body Side reflectors — intact, clean, visible

Exterior Walk-Around — Passenger Side & Rear

Passenger side tires & wheels — repeat driver side inspection criteria Emergency exit door (passenger side) — opens from inside and outside, hinge pins intact Taillights — red lenses, brake lights and turn signals function Backup lights — white lights illuminate when transmission in reverse License plate — secure, illuminated, legible Rear bumper — no damage, no rust through, securely mounted Rear emergency door (school bus) — opens from inside, buzzer sounds when opened slightly

Air Brake Test (5-Step Sequence)

For air-braked buses only. Missing any step = automatic failure of inspection portion.

Step 1: Chock wheels. Build air pressure to governor cut-out (120-135 PSI). Note pressure when compressor stops. Step 2: Governor cut-in test. Pump brake pedal. Compressor must restart at 100-110 PSI. Step 3: Static air leak check. Engine off, brakes released — pressure drop less than 2 PSI in 1 minute. Brakes applied — drop less than 3 PSI. Step 4: Low pressure warning. Key on, engine off. Pump pedal. Warning light and buzzer activate at 60 PSI or above. Step 5: Emergency spring brake pop-out. Continue pumping. Spring brakes activate (park brake knob pops out) at 20-45 PSI.

Light Check Sequence (From Driver Seat)

Activate each light in this order. Examiner stands outside to verify.

Identification / clearance lights — first position of headlight switch. All amber front, red rear. Headlights — low beam, then high beam. High beam indicator on dash must illuminate. Left turn signal — front and rear lamps flash at 60-120 flashes per minute. Right turn signal — front and rear lamps flash at correct rate. Hazard flashers — all four lamps flash simultaneously. Brake lights — press brake pedal. Both rear lights brighter than running lights. Backup lights — place transmission in reverse. White lights illuminate. School bus only — alternating flashing amber lights, red lights, stop sign arm, cross gate.

CDL Exam Critical Failure Zones

These items cause automatic failure if missed or described incorrectly.

Steering play measurement — over 2 inches of free play = out of service, automatic failure Tire tread depth — steer tires below 4/32 inch = violation and failure Air brake pop-out pressure — spring brakes not engaging between 20-45 PSI = automatic fail Brake pedal feel — spongy or fading pedal = brake system defect Missing lug nuts — any missing lug nut on any wheel = immediate failure Emergency exit operation — cannot demonstrate operation = automatic failure

Study Notes: Practice on an actual bus at least 10 times before your test date. Speak clearly and point to each component. Memorize the exact PSI numbers for the air brake test — examiners ask for these numbers specifically. The most common failure is rushing through the air brake sequence or forgetting the low pressure warning step.

Ready for your exam? When you can complete the full 30+ point sequence from memory in under 15 minutes without missing steps, schedule your CDL skills test.

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