Pre-Trip Inspection
A systematic seven-step pre-trip walk-around to catch defects before they put you and the public at risk.
Endorsement: General Knowledge · Source: FMCSA CDL Manual (public domain)
The pre-trip inspection is the most consistently tested skill on every CDL exam, and the Federal Motor Carrier Safety Regulations require one before every trip. The inspection follows a fixed seven-step sequence that the FMCSA CDL Manual lays out: vehicle overview, engine compartment, inside-cab start-up, headlights and four-way flashers, walk-around, signals, and brake checks. Examiners pay particular attention to whether you can name each suspension, brake, and steering component out loud — pointing alone is not enough.
During the engine-compartment portion, you check oil, coolant, power-steering fluid, water-pump and alternator belt tension and condition, leaks, hoses, and wiring. You then start the engine, check gauges (oil pressure, voltage, air pressure rise), test the parking brake, and check the steering wheel for excessive play. Outside the cab, you inspect every wheel for loose lug nuts, oil leaks at the hubs, brake-drum cracks, slack-adjuster travel, brake-chamber mounting, suspension airbags or springs, U-bolts, shock absorbers, mud flaps, and tires (tread depth at least 4/32 on steers and 2/32 elsewhere, no cuts exposing fabric or cord, matched dual heights).
A defect that affects safety must be repaired before the vehicle is moved. Logging the inspection on the daily Driver Vehicle Inspection Report (DVIR) is required for any commercial vehicle, and any defect noted on a previous DVIR must be either certified as repaired or certified as not needing repair before the next driver may operate the vehicle. Skipping or shortcutting any of the seven steps is the single most common cause of CDL skills-test failure.
Key terms to memorize
- GVWR
- GCWR
- CDL
- CLP
- medical examiner's certificate
- reasonable suspicion
- hours of service
Other General Knowledge topics
- Basic Vehicle Control — Backing, turning, and low-speed maneuvering safely with a vehicle whose blind spots are larger than most cars are long.
- Hazard Perception — Reading the road, recognizing developing problems, and acting before they become emergencies.
- Emergency Maneuvers — Braking, steering, and skid control when something goes wrong.
- Hours of Service — The federal limits on driving and on-duty time, and the records that prove you complied.
Test what you learned
Now that you have the Pre-Trip Inspection material in your head, drill the General Knowledge practice test. The questions are drawn from the same FMCSA source material this article paraphrases. For state-specific framing, jump to your state page and pick the General Knowledge test for your jurisdiction.