CDL Pre-Trip Inspection Checklist: What Examiners Look For

The pre-trip inspection is the first part of your CDL skills test — and the part most students fail. Examiners want to see that you can systematically inspect a commercial vehicle and identify safety issues. Here's exactly what to cover. Engine Compartment Oil level (dipstick between min/max) Coolant level (in reservoir, no leaks) Power steering fluid level Belts and hoses (no cracks, fraying, or leaks) Air compressor (connected, not leaking) Alternator (mounted, wires connected) Water pump (no leaks) Cab / Brake Check Parking brake holds against gentle throttle Air pressure builds to governor cut-out (120-140 psi) Air brake leak test: with brakes applied, pressure drop less than 3 psi/min (single) or 4 psi/min (combination) Low air pressure warning activates (typically 55-60 psi) Spring brakes engage (20-45 psi) All gauges working (oil, temp, voltage, air) Steering wheel play (no more than 10 degrees) Windshield (no cracks in wiper area), wipers work Mirrors adjusted, clean Horn works Seatbelt works Emergency equipment: fire extinguisher (charged), reflective triangles, spare fuses Walk-Around: Driver Side Door closes securely, hinges good Fuel tank (secure, cap on, no leaks) DEF tank (if equipped) Front tire: tread depth 4/32" min, no cuts/bulges, properly inflated, lug nuts tight Wheel seal (no leaks) Suspension (springs, mounts, shock absorbers) Brake components: drum, lining, hoses, slack adjuster (less than 1" play) Front of Vehicle Headlights (low and high beam) Turn signals Clearance lights Bumper (secure, no damage) License plate (visible, current) Passenger Side + Rear Repeat the same tire, suspension, and brake checks for all axles on the passenger side. At the rear, check: Tail lights, brake lights, turn signals Reflective tape (visible, intact) Mud flaps (present, not dragging) Cargo doors (secure, latched) Coupling System (Combination Vehicles) Fifth wheel: locked, no gap between apron and plate Kingpin (engaged in fifth wheel jaws) Air and electrical lines (connected, not dragging, no leaks) Landing gear (raised, crank handle stored) Trailer frame (no cracks) Tips for Passing Use a consistent route — always go in the same order so you don't skip anything Talk out loud — explain what you're checking and why to the examiner Touch components — physically touch or point to each item Practice at least 10 times before your test