Every commercial driver is required by federal law to perform a pre-trip inspection before each trip. Under FMCSA regulations (49 CFR 396.13), you must be satisfied that the vehicle is in safe operating condition before driving. Skip it — or rush it — and you risk a roadside inspection, an out-of-service order, or worse, a catastrophic failure on the highway.
Here's the complete breakdown of the 7 inspection areas every driver needs to know.
1. Engine Compartment
Pop the hood and check the basics. Look for fluid leaks — oil, coolant, power steering, transmission. Verify fluid levels: engine oil, coolant reservoir, windshield washer fluid, and brake fluid if visible. Check belts and hoses for cracks, fraying, or excessive wear. Make sure the battery is secure and terminals are clean.
Key checkpoints:
- Engine oil level and color (milky oil = coolant contamination)
- Coolant level (never open a hot radiator cap)
- Power steering fluid
- Belt tension and condition
- No visible fuel, oil, or coolant leaks
2. Cab / Interior
Before you move an inch, check everything inside the cab. Verify mirrors are clean and adjusted properly — side mirrors, hood mirror, and convex spot mirrors. Check all gauges are operational: oil pressure, coolant temperature, fuel, voltmeter/ammeter. Test the horn, wipers, and defrost. Make sure your seatbelt is functional and your emergency equipment is present: fire extinguisher, three reflective triangles, and spare fuses.
Key checkpoints:
- All warning lights clear after startup
- Air pressure builds to operational range (90–120 PSI)
- Clutch and throttle free play within spec
- Emergency brake engages and holds
- Hazard flashers work
3. Lights
Walk around and test every light. This is one of the top reasons drivers get cited during inspections. Have a helper or use reflective surfaces to verify all lights function.
Key checkpoints:
- Headlights (low and high beam)
- Taillights and brake lights
- Turn signals (front and rear)
- Marker lights and clearance lights
- Reflectors clean and not cracked
- Reverse lights and backup alarm (if equipped)
4. Steering
With the truck running and brakes set, check steering play. Excessive lash (more than 10 degrees for power steering) is an automatic out-of-service violation. Check the steering column for looseness and verify the steering gear box mounts are secure.
Key checkpoints:
- Steering wheel free play within limits
- No unusual pulling to one side
- No binding or resistance when turning
- Tie rods and drag link visible and secure
5. Brakes
Brakes are the #1 safety system on your truck. Test both service brakes and parking brake. For air brakes: key off, let pressure build, then fan the brakes to verify the low-pressure warning activates above 60 PSI. Check brake chambers, slack adjusters (automatic or manual), and brake lines for damage.
Key checkpoints:
- Air pressure builds to 90–120 PSI within 3 minutes
- Low pressure warning activates at 60 PSI or above
- Air loss rate within limits (3 PSI per minute at idle)
- Brake drums/rotors not cracked, worn, or overheated
- Brake hoses not chafing on frame or wheels
6. Tires and Wheels
Tires cause thousands of accidents annually. Check every tire — front steer tires especially. Look for tread depth (minimum 4/32" on steers, 2/32" on others), sidewall cuts, bulges, and proper inflation. Inspect lug nuts for looseness (check for rust streaks, which indicate movement). Look at the wheel rims for cracks.
Key checkpoints:
- Tread depth on all tires
- No bulges, cuts, or exposed belts
- Valve stems and caps in place
- Lug nuts tight — no rust streaks or missing nuts
- No mismatched tires on same axle (size and type)
- Mud flaps in place and secure
7. Coupling Devices (Combination Vehicles)
If you're pulling a trailer, the fifth wheel and coupling are critical. Inspect the fifth wheel mounting bolts, the locking mechanism (kingpin should not pull out when you tug the trailer), and the apron and release arm. Check all glad hands (air lines), electrical connections, and the safety chains or cables.
Key checkpoints:
- Fifth wheel properly greased and secured
- Kingpin fully locked — conduct tug test
- Glad hands coupled and air lines not kinked
- Electrical cable connected and lights functional
- Landing gear fully raised and crank secure
- No trailer sway or bounce indicating improper coupling
Build the Habit
The pre-trip inspection isn't just a legal requirement — it's your first line of defense against breakdowns and violations. Budget 30–45 minutes before every dispatch. Walk the same path every time so nothing gets missed.
One thing professional drivers know: every DOT officer knows who does thorough pre-trips and who rushes them. A complete, well-documented inspection is your best defense if something goes wrong on the road.
Download our printable Pre-Trip Checklist PDF for $9 — 40+ points, DOT-formatted, instant download. Take it on every run and sign it daily. Get the Pre-Trip Checklist →