CDL Skills Test Prep
Pre-Trip Inspection Study Guide
The pre-trip inspection is the first part of your CDL skills test — and the one most students fail. This guide shows you exactly what's required: watch a full inspection, then practice naming and verbally explaining all 43 required parts so you do it perfectly on test day.
Step 1 — Watch a Full Pre-Trip Inspection
Watch how a complete CDL pre-trip inspection is performed from start to finish. Notice how the driver points to each part and says out loud what they are checking — that is exactly what the examiner wants to see and hear.
Video not loading? Watch the full pre-trip inspection on YouTube.
Why the Pre-Trip Matters
- Safety first — catching a defect in the lot prevents a brake failure, blowout, or fire on the highway.
- Federal law (49 CFR 396.13) requires the driver to be satisfied the vehicle is safe before driving.
- The pre-trip is a graded, hands-on portion of the CDL skills test — you must point to and verbally identify each item.
- Out-of-service violations from a missed defect cost you time, money, and points on your record.
- A consistent routine builds the habit you'll use every single day as a professional driver.
Step 2 — Do It Virtually
Now it's your turn. For each part, point to it (in your mind or on a truck) and say out loud what you're checking. Reveal the examiner-approved answer and grade yourself. Work through all 43 required parts.
Engine CompartmentPart 1 of 43
Open the hood. Point to each part and state what you are checking.
Oil Level
Point to this part and say out loud what you are checking. Then reveal the examiner-approved answer.
Full Required Parts Checklist
Use this as a quick reference to memorize the order of your walk-around.
Engine Compartment
- Oil Level: Engine oil is at the proper level, dipstick reads within the safe range.
- Coolant Level: Coolant is at the proper level in the reservoir, no leaks.
- Power Steering Fluid: Power steering fluid is at the proper level, no leaks, hoses secure and not chafed.
- Water Pump: Water pump is securely mounted, not leaking, belt is not frayed and has proper tension.
- Alternator: Alternator is securely mounted, wiring is intact, belt is snug with no more than ¾-inch play.
- Belts: Belts are not frayed, cracked, or worn, with proper tension of no more than ¾-inch play.
- Steering Box & Hoses: Steering box is securely mounted, not leaking, hoses are not cracked or leaking, no missing bolts.
- Steering Linkage: Steering linkage, gears and rods are not worn or cracked, joints and sockets are not worn, cotter keys present.
- Leaf Springs / Shocks: Springs are not cracked or shifted, shock absorbers are secure and not leaking, mounts not cracked.
- Air Compressor: Air compressor is securely mounted, gear or belt driven; if belt driven the belt is in good condition.
Front of Vehicle
- Steering Tire: Tire is properly inflated, tread depth at least 4/32, no cuts or bulges, valve cap in place.
- Steer Rim: Rim has no cracks, no welds, no bent or damaged areas.
- Lug Nuts: All lug nuts are present and tight, no rust streaks, no shiny threads.
- Hub Oil Seal: Hub oil seal is not leaking and oil level is adequate if sight glass is present.
- Headlights & Turn Signals: Headlights, turn signals and 4-way flashers are clean, working, and the correct color.
- Windshield & Wipers: Windshield is clean with no large cracks, wiper blades are not worn and arms have proper spring tension.
Driver Side / Cab
- Door & Mirrors: Door opens and closes properly, hinges secure, mirrors and brackets are clean and not damaged.
- Fuel Tank: Fuel tank is securely mounted, not leaking, cap is tight, and tank straps are secure.
- Battery Box: Battery is secure, box is mounted properly, cover is in place, connections are tight and not corroded.
- Drive Tires: Drive tires properly inflated, tread depth at least 2/32, no cuts or bulges, tires not touching each other.
- Drive Axle Seal: Axle seal is not leaking.
- Suspension / Air Bags: Springs, hangers and U-bolts are secure and not cracked; air bags are not leaking and mounts are solid.
- Exhaust System: Exhaust system is secure, not leaking, not touching any wires, hoses or fuel lines.
- Frame: Frame has no cracks, no broken or missing parts or bolts.
Coupling System
- Fifth Wheel: Fifth wheel is securely mounted, no missing or damaged parts, properly greased, jaws locked around the kingpin.
- Kingpin / Apron: Kingpin is not bent, the apron is flush against the fifth wheel, no space between them.
- Locking Jaws: Locking jaws are fully closed and locked around the shank of the kingpin.
- Release Arm: Release arm is in the locked position and the safety latch is engaged.
- Air & Electrical Lines: Air lines and electrical line are properly connected, secured, not cut, cracked, or tangled, no leaks.
- Landing Gear: Landing gear is fully raised, handle is secured, no missing parts, not bent or damaged.
Rear of Vehicle
- Rear Lights & Reflectors: Tail lights, brake lights, turn signals and reflectors are clean, working, and the correct color.
- Mud Flaps: Mud flaps are not damaged and are securely mounted.
- Doors / Ties / Straps: Cargo doors close securely; ties, straps and chains are secure and not damaged.
- Rear Tires & Rims: Rear tires properly inflated, adequate tread, rims not cracked or bent, lug nuts present and tight.
- License Plate & Light: License plate is secure and the plate light is clean and working.
In-Cab & Air Brake Check
- Safe Start: Clutch in, transmission in neutral, start engine, and listen for unusual noises.
- Gauges: Oil pressure, air pressure, temperature, voltage and ammeter gauges are reading in the normal range.
- Air Leak Test (Static): Engine off, key on, full brake applied — air loss is within limits (≤3 psi single, ≤4 psi combo in one minute).
- Low Air Warning: Pump the brakes; low air warning light and buzzer activate before pressure drops below 60 psi.
- Spring Brakes Pop Out: Continue pumping; the parking/spring brake valves pop out between 20 and 45 psi.
- Build-Up Rate: Start engine; air pressure builds from 85 to 100 psi within 45 seconds.
- Service Brake Test: Release brakes, roll forward at about 5 mph, apply the brake — vehicle stops with no pulling to either side.
- Parking Brake Test: Set the parking brake, gently pull against it — the brake holds the vehicle.