The vehicle-inspection portion of the CDL skills test requires the applicant to identify components, explain what is being checked, and recognize unsafe conditions. Test sections and wording vary by state and vehicle, so use this route with the current manual issued by your licensing state.
1. Engine compartment
- Fluid levels and visible leaks.
- Belts, hoses, wiring, and secure mounting.
- Alternator, water pump, air compressor, and power-steering components as equipped.
- Steering linkage, frame, suspension, brake components, wheel, and tire.
2. Cab and start-up
- Safe entry with three points of contact.
- Seat belt, mirrors, windshield, wipers, heater and defroster.
- Gauges, warning lamps, horns, and emergency equipment.
- Lighting indicators and safe-start procedure.
3. Brake checks
Perform the exact air or hydraulic procedure required for the representative vehicle. For air brakes, know pressure build, governor operation, applied leakage, low-air warning, spring-brake application, parking-brake check, and service-brake check. Verbalize the thresholds from your state's current manual.
4. Steering, suspension, brakes, wheels, and tires
Move axle by axle in the same order. Identify secure steering parts, springs or air bags, mounts, shocks, brake hoses, chambers, pushrods, slack adjusters where equipped, drums or rotors, linings or pads, rims, lug nuts, hubs, seals, valve stems, tread, inflation, and tire condition. Federal rules generally require at least 4/32-inch tread depth in major grooves on front tires and 2/32-inch on other tires, but the test expects complete condition checks.
5. Vehicle sides and rear
- Doors, mirrors, fuel and DEF tanks, steps, catwalk, frame, and exhaust.
- Lamps, reflectors, reflective tape, splash guards, and license plate.
- Cargo body, doors, liftgate, or securement equipment as applicable.
6. Coupling and trailer
For a combination, inspect fifth-wheel mounting and condition, locking jaws, kingpin, apron, release arm, air and electrical lines, glad hands, landing gear, frame, cross members, suspension, brakes, axles, wheels, tires, doors, lights, and required reflectors. Confirm no improper gap and that lines are supported.
7. Light check
Verify low and high beams, clearance and identification lamps, turn signals, four-way flashers, brake lamps, tail lamps, and reflectors. Use a helper only according to the testing procedure.
How to practice efficiently
- Use one physical route so sequence becomes automatic.
- Point to or touch the correct component when safe.
- Describe condition and safety purpose, not only the component name.
- Practice on the same vehicle type used for testing.
- Have an instructor score omissions against the state manual.
Study the air-brake guide separately and use the maintenance guide after licensing.