Pre-trip Inspection Guide for Class B Commercial Driver Licenses

All About DOT Audits: An Evolving FMCSA Enforcement Tool

Learn the basics for staying prepared and compliant in the event of an audit

There’s a lot that goes into CDL pre-trip inspections. There’s a lot to remember, and different classes of CDL inspections, so it’s important to educate yourself thoroughly so that you’re fully prepared for your class of CDL inspection and don’t forget anything important. Below, we’ll walk you through a thorough guide for class B CDL pre-trip inspection.

Things to Remember Before You Start

It’s important that you identify the item you’re inspecting by touching it or pointing to it. You’ll need to explain how you know the part you’re inspecting is in good condition. Point out any and all defects you notice. This is important to the process so that you receive proper credit.

Inspect the Outside of the Truck

  • Hood and Doors: Make sure the hood is not damaged and is securely locked. Doors should open and close properly. Check that the hinges aren’t broken or bent and that the seal is in place and shows no signs of damage.

  • Steps: These should be mounted securely, with no excessive debris and no missing hardware.

  • Fuel Tank: Make sure the fuel tank is securely mounted and not leaking. The cap should be tight and the seal intact. Check to make sure the safety chain is in place.

  • Windshield: The windshield, like the lights, should be clean and not cracked or broken in any way.

  • Bumper: Lastly, the bumper should be well mounted and in good condition, and the registration plate should be clean and visible with a valid sticker.

Leaks, Leans, and Lights

  • Leaks: Before you open the hood and start poking around in there, it’s important to check under the truck. You do this to ensure no wires are hanging down and no leaks are present. There are two types of leaks that can appear, one is oil from the transmission and engine. The other is fluid that comes from the power steering or cooling system.

  • Leans: Once you’ve confirmed that nothing is leaking, check that the truck itself isn’t leaning. If it is, that could indicate a suspension problem or low tire pressure.

  • Lights: Finally, it’s time to check the lights on the top and front of the truck. The lights should not only be in working order, but they should be the proper color, clean, not broken, and not cracked.


  • Tires: Inspecting tires is a visual assessment, but it’s important to pay close attention. First, ensure that no bubbles or cuts are present. Then check that there is no space between the tires and the rims. Lastly, make sure the air pressure is correct and that the tread is worn evenly.

  • Rim: The rim should show not be bent or show signs of cracks or welding repairs.

  • Lug Nuts: Lug Nuts should be tightly in place, with no shiny threads or rust trails. There should be no signs of cracks or breaks. And all lug nuts must be present.

  • Valve Stem: Finally, the valve stem should be securely mounted, with a metal cap, and should not be damaged in any way.

Fluid Check

  • Coolant Reservoir: First, take a look at the coolant reservoir. Here, you’re checking to make sure the coolant is at a proper level, the reservoir is mounted securely, and there are no leaks. Check the hose for signs of damage, and make sure that it, too, is securely mounted.

  • Oil: Next, move on to the oil. You should describe the procedure for checking the oil. First, remove the dipstick, wipe it completely clean, then re-insert it into the oil, remove, and check the level. The correct oil level is at, or below FULL but above ADD.

  • Power Steering Reservoir: And finally, you should check the power steering reservoir. Indicate where the dipstick is and make sure the power steering is at the proper level. Check that the reservoir is not leaking and is securely mounted. The hose should show no signs of leaks or damages, and it too, should be properly mounted.

Engine Components

  • Alternator: The alternator should be securely mounted without any signs of damage. No bolts or parts should be missing. And wires must have good connections, without any fraying. Belts should have no more than ¾ inch of play, and should show no signs of fraying or cuts.

  • Water Pump: To locate the water pump, follow the bottom radiator hose. The pump should be securely mounted without any signs of damage or leaks. Hoses should not be leaking and must be securely attached. Belts should show no signs of being cracked, frayed, cut, or damaged in any other way. And they should have more than ¾ inch of play.

  • Air Compressor: Finally, check to make sure the air compressor is securely mounted, without any signs of damage and no audible leaks. There should be no missing bolts or parts. And the compressor belt should show no signs of damage or fraying. Make sure the best has no more than ¾ inch of play.


  • The Steering Shaft: Ensure that the shaft is securely mounted without excessive play and shows no signs of damage.

  • The Power Steering Box: The box should be mounted to the frame without damage. Check that no leaks are present.

  • The Pitman Arm: This should be securely mounted without damage or cracks. Castle nuts and cotter pins must be present and without damage. Drag Link: When inspecting the drag link, make sure it is properly secured, without damage, and that the rubber bushings also show no signs of damage.

  • Upper and Lower Control Arms and Tie Rod: Finally, check that these are not bent or broken and that all hardware is present and securely mounted.


  • Spring Mounts: There are front and rear spring mounts. Both should be securely mounted to the frame with no signs of damage.

  • Leaf Springs: It’s important that these aren’t missing, cracked, or broken, but you should check to make sure they’re not shifting (scissoring) either.

  • Shock Absorber: Make sure it’s mounted securely and not bent or dented. Check for leaks. And make sure the rubber bushings are not worn.

  • U-Bolts: These shouldn’t be broken, cracked, missing, or loose.


  • Air Hose to Brake Chamber: Check to make sure they’re mounted securely at both ends and show no signs of splits or cuts. Also, check for leaks.

  • Brake Chamber: Check to make sure that it shows no damage, is mounted securely and is not leaking.

  • Slack Adjuster: Check that the pushrod is at a 90-degree angle to the chamber and that there is no more than 1 inch of free play at the pushrod with the brakes released. Also check for dents, breaks, and loose or missing parts.

  • Brake Pads: These should show no signs of breaks or cracks, and should be mounted securely. Check that they have a minimum of ¼ inch pad depth. Also check for signs of heat, such as cracking or glazing.

  • Brake Drums: Check for cracks or bending, and ensure that it’s mounted securely. Next, check for oil leaking from an inner oil seal. Ensure that it’s free of debris and that there is no blueing from excessive heat.

Check the Cab of the Truck

  • Mirrors: It’s not only the outside mirrors you need to check. These mirrors should be properly adjusted, clean, and show no signs of damage.

  • Wipers: Both the arms and blades should be securely mounted with no damage. Don’t forget to check the wiper fluid.

  • Heater/Defroster: Simply make sure that both work properly.

  • Dashboard Indicator Lights: Ensure that both left and right turn signals are functioning. Then check 4-way flashers and your high beams.

Learn More About Class B CDL Pre-Trip Inspections

It may seem exhausting, having to check so many items on a large truck for you Class B CDL pre-trip inspection, but it’s vital to your safety and the safety of others on the road. It’s also important to have a DOT Pre-trip Inspection Checklist and follow it. To make inspecting fleet vehicles, equipment, and other assets a little easier and more manageable, please don’t hesitate to contact us today to start your free trial.