Vehicle Inspection
Vehicle inspection is the first domain of the Louisiana CDL General Knowledge exam. It tests whether you can confirm a commercial vehicle is safe before, during, and after a trip, and whether you know the inspection items and air-brake checks examiners commonly ask about. Louisiana's CDL manual follows the FMCSA model, so the same standards apply in-state.
The seven-step pre-trip method
The pre-trip is organized as: vehicle overview; engine compartment; inside-the-cab inspection; lights; walk-around inspection; signal lights; and brake checks. You are not just reciting a sequence-you must know what a defect looks like and why it matters. Check tires for tread depth, cuts, and inflation; wheels for cracks, rust streaks, and missing lug nuts; brakes for leaks and adjustment; steering for excessive play; suspension for broken leaves or air leaks; exhaust for leaks; and all lights and reflectors for function.
Air-brake checks
With the engine off and the parking brake released, watch the air gauge: leakage should not exceed 3 psi per minute in a single vehicle or 4 psi per minute in a combination. Pump down to confirm the low-pressure warning activates before 60 psi, and continue to confirm the spring brakes apply between 20 and 45 psi. Build pressure back to governor cut-out, usually 120–140 psi.
Worked example
A driver finds a deep sidewall cut exposing cord on an outside drive tire. Because the tire cannot be repaired safely and may fail at highway speed, the correct action is to tag the vehicle out of service and replace the tire-not merely note it for the next shop visit.
Traps
Candidates lose marks by memorizing the order but not the pass/fail standard; forgetting to chock wheels or secure the vehicle before crawling underneath; and assuming a lamp works because it worked on the last trip.