The CDL pre-trip inspection checklist, step by step
What a driver checks before rolling a commercial vehicle — in the order most CDL manuals teach it — with the air brake check and the numbers each step has to hit.
The short version. Before driving a commercial motor vehicle, the driver has to be satisfied that eleven parts and accessories are in good working order (49 CFR 392.7) and has to review the last DVIR (49 CFR 396.13). A good pre-trip covers those items in a fixed order: engine compartment, cab, air brakes, a full walk-around and — on a combination — the coupling.
What the rules require
Two federal rules frame the pre-trip:
- 49 CFR 392.7 says no commercial motor vehicle may be driven unless the driver is satisfied that the service brakes (including trailer brake connections), parking brake, steering mechanism, lighting devices and reflectors, tires, horn, windshield wipers, rear-vision mirrors, coupling devices, wheels and rims, and emergency equipment are in good working order.
- 49 CFR 396.13 says that before driving, the driver must be satisfied the vehicle is in safe operating condition, review the last driver vehicle inspection report, and sign it if defects were noted — acknowledging that the repairs were certified.
The federal rules do not require a written pre-trip report, but plenty of carriers do. The CDL skills test also includes a vehicle inspection, and state CDL manuals teach a full walk-around in roughly the order below.
Before you start
- Park on level ground, set the parking brake and chock the wheels if you will be releasing the brakes for the air check.
- Read the last DVIR for this truck and trailer. If it lists defects, find the repair certification before you go any further.
- Carry a flashlight, a tire pressure gauge, a tread depth gauge and gloves.
- Look under the vehicle for fresh puddles before you open anything — oil, coolant, fuel or brake fluid on the ground is the first defect of the day.
1. Engine compartment
With the engine off:
- Fluids: engine oil, coolant, power steering and washer fluid at the right levels.
- Leaks: oil, coolant, fuel or hydraulic fluid on the engine, hoses or ground.
- Belts: tension, cracks and fraying on belts driving the alternator, water pump and air compressor (where belt-driven).
- Hoses and wiring: cracks, chafing, loose clamps, worn insulation.
- Steering: the steering box and linkage secure, with no missing nuts, bolts or cotter pins and no leaks.
- Front suspension and brakes: springs, mounts and shocks intact; brake chambers, hoses, slack adjusters, drums or rotors and linings undamaged.
2. In the cab
- Start-up: oil pressure comes up within a few seconds, air pressure builds, charging is normal, and no warning lights or buzzers stay on.
- Steering: no excessive free play in the wheel.
- Controls: horn, wipers and washers, defroster, heater.
- Lights: headlights high and low, turn signals, four-way flashers, clearance and marker lights.
- Mirrors and windshield: clean, properly adjusted, no cracks or obstructions in the driver’s view.
- Emergency equipment: a properly charged and rated fire extinguisher, warning triangles, and spare fuses where your vehicle requires them.
- Seat belt: latches and adjusts.
3. The air brake check
CDL manuals teach a fixed sequence for vehicles with air brakes. The numbers below come from the dual air brake section of the Georgia CDL manual, which follows the national model most states use; always check your vehicle manufacturer’s specifications too.
| Check | How | Pass if |
|---|---|---|
| Build-up rate | Engine at operating speed, from 85 psi | Pressure builds from 85 to 100 psi within 45 seconds (dual air systems) |
| Governor cut-out and cut-in | Let pressure build, then pump the brake pedal down | Compressor stops at about 125 psi and restarts at about 100 psi |
| Leakage, brakes released | Engine off, wheels chocked, parking brake released, wait one minute | Loss under 2 psi per minute (single vehicle) or 3 psi (combination) |
| Leakage, brakes applied | Hold the service brake fully applied for one minute | Loss no more than 3 psi per minute (single) or 4 psi (combination) |
| Low-air warning | Fan the brake pedal to reduce pressure | The warning comes on before pressure drops below 60 psi |
| Spring brakes | Keep fanning the pedal | Spring brakes apply automatically in the manufacturer’s range, usually 20 to 45 psi |
| Parking and service brakes | Try to pull forward against the parking brake; then brake at about 5 mph | The parking brake holds; the service brake stops the vehicle without pulling |
Also check the slack adjusters during the walk-around: with the brakes released, a slack adjuster that moves more than about an inch where the pushrod attaches when pulled by hand probably needs adjustment.
4. The walk-around
Start at the driver’s side front and work around the vehicle, checking the same things on every axle:
- Tires: at least 4/32 of an inch of tread on steer tires and 2/32 on all others, measured in a major groove (49 CFR 393.75). No exposed ply or belt, no tread or sidewall separation, no cuts to the cords, no flat or audible leak. Check inflation, and that dual tires are not touching.
- Wheels and rims: no cracks or bends, no missing or loose lug nuts, no rust trails from lug nuts, matching rims.
- Brakes: chambers, hoses and slack adjusters secure and undamaged; drums or rotors without cracks; no leaking hubs.
- Suspension: no broken or shifted spring leaves, cracked hangers or leaking air bags.
- Frame and body: no cracks or bends; doors, panels and cargo secure.
- Fuel and exhaust: tanks and caps secure, no leaks; exhaust system secure, with no leaks near the cab.
- Lights and reflectors: every lamp working, lenses clean and unbroken, reflectors in place.
5. Coupling (combination vehicles)
- Fifth wheel: securely mounted, locking jaws closed around the kingpin shank, release arm in the locked position, no gap between the upper and lower fifth wheel.
- Air and electrical lines: no cuts, chafing or tangles; glad hands sealed and not leaking; lines secured so they will not drag or snag.
- Landing gear: fully raised, with the crank handle secured.
- Sliding fifth wheel or tandems: locked in place.
- Tug test: with the trailer brakes set, pull gently against the trailer to confirm the coupling holds.
The pre-trip at a glance
| Area | Check | Do not drive if |
|---|---|---|
| Engine compartment | Fluids, leaks, belts, hoses, steering linkage | Active leaks, a missing steering fastener, a broken belt |
| Cab | Gauges, warning lights, horn, wipers, lights, mirrors, emergency kit | A brake or oil pressure warning, no wipers in rain, missing extinguisher or triangles |
| Air brakes | Build-up, governor, leaks, low-air warning, spring brakes | Any check outside the limits above |
| Tires and wheels | Tread depth, damage, inflation, lug nuts | Steer tread under 4/32, others under 2/32, exposed ply, flat or leaking |
| Brakes and suspension | Chambers, slack adjusters, springs, air bags | Broken springs, out-of-adjustment brakes, leaking air |
| Coupling | Fifth wheel, jaws, lines, landing gear | Jaws not locked, a gap at the fifth wheel, damaged lines |
What to do when you find a defect
If it affects safe operation, the truck does not move. Report it, write it on the inspection report, and tell whoever dispatches the vehicle. Under 49 CFR 396.11, the carrier has to repair any listed defect likely to affect safety — and certify the repair, or that repair was unnecessary — before the vehicle runs again.
Pre-trips and post-trips on a phoneMotentra’s DVIR app walks drivers through the inspection items, puts the trailer on the report and turns every defect into a task for the shop — critical items at high priority.
See the DVIR appRelated guides: DVIR requirements, minimum tire tread depth for trucks and DOT annual inspection requirements.
Frequently asked questions
Is a pre-trip inspection required by law?
What is the difference between a pre-trip inspection and a DVIR?
What tread depth do truck tires need?
What are the air brake leakage limits?
At what pressure should the low-air warning come on?
Sources. 49 CFR 392.7, 49 CFR 396.13 and 49 CFR 393.75 (eCFR); Georgia Department of Driver Services, CDL manual, dual air brakes. This guide is general information, not legal advice — your vehicle manufacturer’s specifications and your carrier’s policy come first.