A pre-trip inspection is two different things: a legal duty before every trip, and the first part of the CDL skills test. The legal duty is short: under 49 CFR 392.7 and 396.13 the driver must be satisfied that the brakes, steering, lights, tires, horn, wipers, mirrors, coupling devices, wheels and emergency equipment work, and review the last inspection report. The test is longer and scored item by item. This checklist follows the order and wording of the CDL vehicle inspection test in the AAMVA model manual that state CDL manuals reproduce.
The legal pre-trip, every trip
49 CFR 392.7(a): no CMV shall be driven unless the driver is satisfied that these parts and accessories are in good working order, and the driver must use them when needed:
- service brakes, including trailer brake connections;
- parking (hand) brake;
- steering mechanism;
- lighting devices and reflectors;
- tires;
- horn;
- windshield wiper or wipers;
- rear-vision mirror or mirrors;
- coupling devices;
- wheels and rims;
- emergency equipment.
392.8 adds that the emergency equipment required by 393.95 must be in place and ready. 392.9(a) adds cargo: the load must be properly distributed and secured, and the tailgate, doors, tarps and spare tire secured.
49 CFR 396.13: before driving, the driver shall (a) be satisfied that the vehicle is in safe operating condition; (b) review the last driver vehicle inspection report if one was required under 396.11(a)(2)(i); and (c) sign it to acknowledge the review and that there is a certification that required repairs were made. A report is only required when a defect was found, so on many mornings there is nothing to sign. The end-of-day side is on the driver vehicle inspection report page.
Time spent inspecting counts as on-duty time: the definition in 395.2 includes "all time inspecting, servicing, or conditioning any commercial motor vehicle at any time."
How the CDL vehicle inspection test is scored
49 CFR 383.113(a)(1) requires applicants to identify each safety-related part and explain what needs to be inspected, covering the engine compartment, cab and engine start, steering, suspension, brakes, wheels, side of vehicle, rear of vehicle, and special features of a tractor-trailer, school bus or coach. The state manuals built on the AAMVA model (we used the Virginia DMV 60A edition, section 11) add the practical rules:
- You must "name, point to and/or touch, and fully explain" what you are inspecting each item for, or you get no credit.
- You inspect one axle during the test, but must be ready to do the same inspection on all of them.
- You may use the manual’s checklist, but no additional markings may be written on it before the test.
- You will not have to crawl under the vehicle. A vehicle with components marked or labeled by anyone other than the manufacturer cannot be used.
- Exit and enter facing the vehicle with three points of contact; set the parking brake and put the vehicle in neutral when you get out.
- Failing to follow instructions, or an unsafe act such as forgetting the parking brake, "may result in an automatic failure."
- The vehicle inspection test must be passed before the basic control skills test.
The skills test as a whole is on the CDL skills test page. The checklist below is section 11 in order, with what to say for each item.
1. In-cab and engine start
| Item | What to check and say |
|---|---|
| Dash indicator lights | Left and right turn signal indicators, four-way flasher indicator, high beam indicator, ABS light (on combinations the trailer ABS light should come on then go off), DEF light if equipped. The lights themselves are checked later from outside. |
| Emergency equipment | Spare electrical fuses, or say the vehicle uses circuit breakers; fire extinguisher charged and secured; three red reflective triangles, or six fusees, or three liquid-burning flares. |
| Windshield and mirrors | Clean, no cracks or obstructions except an inspection sticker; mirrors clean and adjusted, or cameras clean, working and viewable. |
| Wipers and washers | Arms and blades secure and undamaged; turn wipers on and off; washer fluid present and washers work. |
| Heater and defroster | Demonstrate both work. |
| Horn | Air horn and/or electric horn work. |
| Parking brake check | With the parking brake on (trailer brakes released on a combination), foot off the service brake, gently pull forward: the parking brake must hold. |
| Trailer brake check (combination) | Parking brake released, trailer parking brake on, gently pull forward: the trailer brake must hold. This also checks the coupling. |
| Service brake check | Pull forward at 5 mph and apply the foot brake: the vehicle stops and does not pull to either side. |
On emergency equipment, note that the federal rule and the test are not identical. 49 CFR 393.95 now lists a fire extinguisher (5 B:C, or two of 4 B:C, and 10 B:C for placarded hazmat) and warning devices for stopped vehicles (three bidirectional reflective triangles or at least 6 fusees); paragraphs (b) to (e) are reserved. The test still asks you to point out spare fuses or name the circuit breakers, so say it.
2. The air brake check: four parts, automatic fail if you miss one
The manual is blunt: "Failure to explain and demonstrate (perform) all four (4) parts of the air brake check correctly will result in an automatic failure of the CDL Vehicle Inspection test." Know the manufacturer’s figures for your test vehicle; the manual’s numbers apply when the manufacturer does not specify otherwise.
- Air gauge and governor cut-out. Chock the wheels if required, start the engine, check that the gauge works, build pressure to governor cut-out and identify it: approximately 120 to 140 psi or the manufacturer’s level.
- Air leakage rate. Engine off, key on, parking brake released (and the tractor protection valve on a combination). Fully apply the foot brake, let the gauge stabilize, and hold for one minute. The drop must be no more than 3 psi in one minute for a single vehicle (or with a trailer without air brakes), or 4 psi for a combination.
- Low air warning. Key still on, fan off pressure by pumping the brake. The low air warning (buzzer, light, flag) must come on before pressure drops below 55 psi.
- Spring brake pop-out. Keep fanning. The parking or emergency brake valve should close (pop out) between 20 and 45 psi, or at the manufacturer’s level. On a combination, the tractor protection valve and trailer brake valve should pop at the same time as, or before, the tractor’s. If the valves are not designed to pop out, listen for air discharging; with dual systems, explain that the valve will not pop on loss of pressure in only one system.
The 55 psi figure matches the federal equipment rule. 49 CFR 393.51(c)(2) requires older air-braked power units (those not built to FMVSS No. 121) to have a warning that operates whenever service reservoir pressure is at 55 psi and below, or half the governor cut-out pressure, whichever is less; newer vehicles must meet FMVSS No. 121. Practice the sequence with the air brakes practice test.
Hydraulic brakes instead
For hydraulic brakes the test is also automatic-fail if done wrong. Check the warning indicators; with the transmission in park, pump the pedal three times and hold it down for five seconds (or follow the manufacturer’s procedure): the pedal should not sink after the initial application and should stay firm with reserve travel. Check hydraulic power assist if equipped.
3. Lights check
From outside the vehicle, check that the left and right turn signals, four-way flashers, low beams, high beams, clearance and marker lights, taillights and brake lights work. Brake lights must come on with the brake and go off when released. On a combination, you inspect only the rear of the trailer. The examiner may help on request, but you direct the examiner to each position and name each light. "Failure to identify or inspect any required light will result in no credit."
4. Front of vehicle and engine area (engine off)
| Item | What to check and say |
|---|---|
| Lenses | Front lenses proper color, clean, not broken or missing. |
| Fluid levels | Engine oil, coolant, power steering fluid, brake fluid (hydraulic brakes only). Show where the dipstick or sight glass is and say the level should be between add and full. Do not open the radiator cap on a hot engine. |
| Fluid and air leaks | Puddles under the vehicle, drips around the engine and transmission, hoses and air lines not leaking. |
| Steering system | Steering box securely mounted and not leaking; hoses not cracked or leaking; linkage, arms and rods not worn or cracked; joints not loose; no missing nuts, bolts or cotter pins. |
5. Steering axle (and every axle in real life)
| Item | What to check and say |
|---|---|
| Tire inflation | Check with a tire gauge. Kicking the tire or hitting it with a mallet gets no credit. With an automatic inflation or monitoring system hosed to the valve stems, say so and check it works. |
| Tire condition | No cuts exposing plies in tread or sidewall, valve caps present, stems not damaged, no bulges, no mismatched duals. |
| Tread depth | With a tread depth gauge in the major grooves: 4/32 inch on steering axle tires, 2/32 on all others. |
| Rims | Not damaged, cracked or bent; no welding repairs; no rust trails; bolt holes not elongated. |
| Lug nuts | All present, not loose, no rust trails or shiny threads, no bent or broken studs. |
| Suspension | Leaf springs not missing, shifted, cracked or broken; coil springs not broken; mounts intact; U-bolts not broken or loose; air bags secure and not leaking; shocks secure and not leaking; vehicle sitting level. |
| Brake lines and hoses | Not leaking, not cracked, worn or frayed; couplings secure. |
| Brake contaminants | If visible, no grease or oil on linings, pads, drums or discs. |
The tread figures are the federal ones: 49 CFR 393.75(b) requires at least 4/32 inch on the front wheels of a bus, truck or truck tractor, and 393.75(c) at least 2/32 elsewhere, measured in a major tread groove and not on tie bars, humps or fillets. 393.75(a) bans running on a tire with exposed ply or belt material, tread or sidewall separation, a flat or audible leak, or a cut exposing ply.
6. Side of vehicle
- Lenses and reflectors on the side of the truck and trailer: proper color, clean, not broken or missing.
- Mirrors or cameras: clean, not cracked, brackets not bent and securely mounted.
- Battery: secure, connections tight, no heavy corrosion, cables secure, box or cover secured. If you cannot see the batteries, tell the examiner and describe what you would inspect.
- Fuel tank and DEF tank: securely mounted, cap tight, no leaks from tank or lines.
- Frame: no cracks, broken welds or holes, including the trailer frame and cargo floor; trailer tandem release lever and pins secure.
7. Rear of vehicle or trailer
Rear lenses and reflectors: proper color, clean, not broken or missing. On a combination, only the rear of the trailer.
8. Combination vehicles: coupling
| Item | What to check and say |
|---|---|
| Air and electric lines | Connectors seated, sealed, undamaged and locked on both tractor and trailer (you must check both ends for credit); hoses and cords not cut, chafed, spliced or taped; not tangled, pinched or dragging; listen for air leaks. |
| Fifth wheel skid plate | Securely mounted to the platform; no cracks, breaks or excessive wear; lubricated if applicable. |
| Kingpin, apron and gap | Kingpin not bent or worn; apron not bent or cracked; trailer lying flat on the skid plate with no gap. |
| Locking jaws and release arm | Look into the gap: jaws fully closed around the kingpin with no play; release arm in the engaged position; safety latch in place; sliding fifth wheel pins fully engaged. |
| Pintle hook or ball hitch (other combinations) | Securely mounted; no loose or missing parts; no cracks; drawbar eye or coupler not bent, worn or cracked; safety pins in place; safety chains secure, crossed and not dragging; breakaway cable engaged. |
| Landing gear | Fully raised, no missing parts, crank handle secure, pads undamaged; tractor frame will clear it in turns. |
| Reflective tape | Present and secure on the trailer sides and rear. |
Coupling is also tested in the knowledge exam; the combination vehicles practice test covers it.
Passenger vehicles and school buses
A bus test adds the entry door and lift, emergency exits (open and close at least one, describe the rest, check the exit warnings), passenger seats firmly attached, and passenger mirrors or cameras. A school bus adds the alternating amber and red student lights front and rear, the stop arm and crossing arm, and the first aid and body fluid kits.
Worked example: a spoken item
Example, following the manual’s "name, point or touch, explain" rule. Pointing at a lug nut and saying "lug nuts, good" earns little. What earns credit is closer to: "These are the lug nuts. I’m checking that all are present, none are loose, there are no rust trails or shiny threads that would show looseness, and the studs are not bent, broken or missing." Every item on the checklist follows that pattern: the part, and the defects you are looking for.
What examiners mark down most
- An incomplete air brake check. All four parts, with numbers, or the test ends.
- No tire gauge. Inflation checked by kicking gets no credit.
- Coupling lines checked on one end only. The manual requires both ends.
- Lights not named. Each light has to be identified and checked from outside.
- Getting out without setting the parking brake. An unsafe act that can end the test.
- Writing on the checklist. Not allowed beyond checking items off.
From the test to the job
The test checks one axle; the road checks all of them. The daily habit that matters is the 392.7 list plus the air brake check and the coupling, in the same order every day, and a written report whenever you find a defect. For schools that teach the full routine, see the CDL training directory; for test sites, the CDL testing directory.