CDL Pre-Trip Inspection: What to Expect on Test Day

The CDL skills test has three parts, and the pre-trip inspection is the very first one. Examiners expect you to identify and name specific vehicle components in a specific order. Here's exactly what to expect and how to prepare.

What Is the Pre-Trip Inspection Test?

The pre-trip inspection is a verbal and visual examination of your vehicle before operating it. On the CDL skills test, an examiner will watch and listen as you walk around the vehicle and identify what you're checking and why. It typically takes 30–45 minutes to complete fully.

You can lose points for components you miss, components you identify incorrectly, or skipping parts of the sequence. Enough deductions and you fail the skills test entirely.

The 7 Basic Steps of Pre-Trip Inspection

The FMCSA pre-trip inspection follows a logical sequence. Most examiners expect you to work through the vehicle systematically:

1. Approach the vehicle — Note overall lean, damage, fluids under the vehicle
2. Engine compartment — Check fluid levels, belts, hoses, battery, and engine components
3. In-cab inspection — Gauges, controls, safety equipment, seatbelt
4. Front of the vehicle — Lights, mirrors, windshield, wipers
5. Left side — Fuel tank, exhaust, front axle, tires, wheels
6. Rear of the vehicle/cargo area — Lights, reflectors, tires, frame, landing gear
7. Right side — Mirror image of the left-side inspection

Engine Compartment: What Examiners Look For

The engine compartment check is one of the most detailed parts of the pre-trip. You'll need to identify and check:

• Engine oil level — Must be at or above the MIN line
• Coolant/antifreeze level — Check overflow reservoir (never remove cap on hot engine)
• Power steering fluid — Check reservoir level
• Windshield washer fluid — Filled, no leaks
• Battery — Secure, no cracks, no corrosion on terminals, fluid levels if applicable
• Alternator/belts — Proper tension, no fraying or cracking
• Air compressor — Check belt tension, no leaks
• Engine mounts — No excessive movement

Brakes: The Most Critical Inspection Area

Brake Drums and Pads

Inspect brake drums for cracks (none allowed) and brake lining/pads for thickness. Pads cannot be worn to less than ¼ inch (¼" minimum — memorize this number).

Air Lines and Fittings

Check supply and service air lines for cuts, cracks, and secure connections. Verify glad hands (coupling connectors) are properly sealed.

Spring Brakes

Verify parking brake is properly engaged and spring brake chambers show no visible damage or leaks.

Lights: Complete Checklist

All lights must work properly. Walk the full perimeter and verify:

• Headlights (high and low beam)
• Turn signals (all four corners)
• Hazard lights
• Brake lights
• Tail lights
• Clearance/marker lights (amber front, red rear)
• Reflectors (front, side, rear)

Coupling Inspection (Combination Vehicles)

For Class A vehicles, coupling inspection is a major section:

• Fifth wheel — Properly greased, mounted securely, jaws fully closed around kingpin
• Kingpin — Not bent or cracked, properly seated in fifth wheel
• Landing gear — Fully raised, crank handle secured
• Electrical connection (pigtail) — Properly connected, no bare wires
• Air lines — Blue (service) and red (emergency) properly connected and not chafing
• Safety chains/straps — Present and properly crossed (where required)

Common Pre-Trip Inspection Fails

These are the most common reasons drivers fail the pre-trip inspection portion of the skills test:

• Skipping entire sections (forgetting lights or one side of the vehicle)
• Not verbalizing what they're checking (examiners need to hear you)
• Incorrect fluid identification (confusing coolant with oil)
• Not checking brake lining thickness
• Missing a coupling component (fifth wheel, glad hands)
• Incorrect tire pressure check procedure
• Going out of sequence (which creates a less systematic inspection)

How to Prepare

The best preparation for the pre-trip is physical repetition with an actual vehicle. Walk through the inspection sequence at least 20–30 times before your test day. Many CDL schools will walk you through the sequence with a truck. If you're self-studying, use a practice truck at a rental facility or ask a licensed CDL driver to let you practice on their vehicle.

Start your knowledge prep with our written practice tests at greenlightcdl.com/test/ — the vehicle inspection section is fully covered.