Pre-Trip Inspections

Use the inspection sequence taught by your carrier so you cover each area without skipping steps. Keep your attention on the equipment, avoid distractions, and take the time needed to inspect thoroughly.

Identify the tractor, trailers, and converter dolly assigned to your run. Review your carrier’s inspection checklist and learn where the key components and connections are located on that equipment.

Have your carrier’s inspection checklist and reporting system ready. Record any defects you find and communicate them through the required process so they can be evaluated and addressed before departure.

 Begin directly in front of the truck with the hood closed. Look for leaning, visible damage, puddles, or hanging parts. Inspect the windshield, wipers, headlights, turn signals, clearance lights, grille, bumper, and license plate for condition and secure mounting. Check that lights and glass are clean and unobstructed. This first look helps you spot concerns before opening the hood.

 With the engine off and the vehicle secured, open and support the hood according to the truck manufacturer’s instructions. Begin on the passenger side. Look for leaks, loose components, damaged wiring, and cracked or chafed hoses. Inspect accessible belts and fluid reservoirs located on this side, following the manufacturer’s checking procedure. Never remove a hot cooling-system cap. Component locations vary by truck; use your equipment-specific checklist. Remember "ABC". Is there anything with "Abrasions, Bulges or Cracks". Also, "CBB". Is anything "Cracked, Bent or Broken".

 Move around the front to the driver-side engine area. Check the engine oil using the manufacturer’s procedure and inspect the fluid reservoirs located on this side. Look over accessible steering components, hoses, wiring, belts, and mounting hardware for damage, leaks, looseness, or missing parts. Check both engine areas against your equipment-specific checklist so components are not missed because of their location. Keep clear of hot surfaces and moving parts.

 Continue down the driver side of the tractor. Inspect the steer tire and wheel, steps, handholds, mirrors, door, fuel tank, cap, and mounts. Check the drive tires and wheels, accessible suspension and brake components, and frame for damage, leaks, loose parts, or missing hardware. Check tire pressure with a gauge according to your equipment’s requirements.

Inspect the fifth wheel, mounting hardware, kingpin connection, locking mechanism, and any sliding mechanism using your carrier’s procedure. Check tractor-to-trailer air and electrical connections from a safe position. For doubles, also inspect the converter dolly, drawbar, pintle hook, latch, and safety chains or cables as equipped when you reach those connections. Look for damage, loose or missing hardware, and locks that are not fully secured. Visually verify each coupling; a tug test alone does not confirm that every connection is properly locked.suspension and brake components, and the frame for damage, leaks, loose parts, or missing hardware. Check tire pressure using a gauge according to your equipment’s requirements. Inspect the fifth-wheel mounting, locking mechanism, and tractor-to-trailer air and electrical connections from a safe position.

 Continue along the driver side of each trailer. Inspect the body, frame, landing gear, mounts, lights, reflectors, and reflective tape. Check each tire and wheel, plus accessible suspension, brake components, and air lines, for damage, leaks, loose parts, or missing hardware. Check any sliding tandem locks for proper engagement. With doubles, inspect the converter dolly and connections between trailers using the coupling checks described above before continuing toward the rear.

 At the rear of the last trailer, inspect the doors, hinges, latches, and any required seal. Check the rear lights, reflectors, reflective tape, license plate, mudflaps, and rear impact guard for condition and secure mounting. Verify brake lights, turn signals, and four-way flashers using assistance or your carrier’s approved method. Look beneath the rear from a safe position for damage, leaks, or hanging components before continuing around to the passenger side.

 Walk forward along the passenger side of every trailer and the tractor. Inspect this side’s tires, wheels, accessible brakes and suspension, body, frame, lights, reflectors, and reflective tape. Check trailer landing gear and, with doubles, the dolly and connections from this side too. At the tractor, inspect the fuel tank and mounts, steps, handholds, door, mirrors, and passenger-side steer tire and wheel. Check for damage, leaks, loose or missing parts, and lines or cables that rub or hang.

 Return to the front and confirm that both engine areas have been inspected and all tools and inspection materials are clear. Close and secure the hood according to the manufacturer’s instructions, checking that its latches are fully engaged. Review any defects found during the walkaround and report them through your carrier’s process. Then use the steps and handholds with three points of contact to enter the cab for the in-cab inspection.

Confirm the parking brakes are applied and the transmission is in the proper position before starting the engine. Adjust your seat and mirrors, inspect the seat belt and latch, and secure loose items. Make sure the pedals and floor area are clear, the doors latch properly, and your view through the windshield and mirrors is unobstructed.

Start the engine according to the manufacturer’s procedure. Watch for oil pressure to register normally, check the gauges, and confirm the dashboard completes its normal warning-light checks. Monitor air pressure as it builds. Investigate warning lights that remain on, unusual sounds, or abnormal readings before continuing. Never run the engine in an enclosed area without proper ventilation.

 Locate the fire extinguisher and check its charge indicator, secure mounting, and accessibility. Confirm your warning triangles are present and in usable condition. Check any spare fuses required for your equipment and any additional emergency supplies specified by your carrier. Know where these items are stored before you need them.

 Check the windshield and mirrors for damage, cleanliness, and secure mounting. Test the wipers, windshield washer, heater, and defroster. Check the horn and operate the lighting controls, confirming the appropriate dashboard indicators respond. Make sure you can identify and reach the controls you need before driving.

 This check includes air-pressure buildup, air leakage, the low-air warning, automatic spring-brake application, and parking and service-brake operation. Each test requires a specific setup and sequence. Before testing, secure the vehicle on suitable level ground and use wheel chocks whenever the procedure requires releasing the parking brakes. Follow the procedure for your tractor and trailer configuration. We’ll cover each test separately below.

 Park on firm, level ground with adequate clearance around the entire combination. Apply the parking brakes, place the transmission in the manufacturer-specified position, and chock the wheels before any test that requires releasing the parking brakes. Confirm the tractor, trailers, and converter dolly are properly connected. Identify both air-pressure gauges and the brake controls. Keep everyone clear and use the test procedure for your specific equipment and combination.

 With the vehicle secured, run the engine at the manufacturer’s recommended testing RPM and watch both air-pressure gauges. Time the pressure rise through the specified test range. A common dual-air-system benchmark is 85 to 100 psi within 45 seconds; larger tanks and some combinations require manufacturer-specific criteria. Continue building pressure and note where the governor cuts out. Then, following the equipment’s procedure, reduce pressure with brake applications and confirm the compressor cuts back in. Compare both readings with the manufacturer’s specifications. Report slow buildup or abnormal governor operation before departure.

Fully charge the air system. With the wheels chocked, transmission in neutral, and vehicle secured against movement, shut off the engine and release the parking brakes. Keep your foot off the service-brake pedal. Allow the pressure to stabilize, then watch the air-pressure gauge(s) for one full minute and record the loss. As a general CDL guideline, air loss should be less than 2 psi in one minute for a single vehicle and less than 3 psi in one minute for a combination vehicle. Always follow the current CDL manual for your state, along with the vehicle manufacturer’s and carrier’s procedures. Excessive air loss requires correction before operation.

 Begin with air pressure at governor cut-out. Keep the wheels chocked and the transmission in neutral. Shut off the engine, release the parking brakes, and fully apply and hold the service-brake pedal. After the initial pressure drop stabilizes, hold the brake for one full minute while watching the air-pressure gauge(s) and listening for leaks. As a general CDL guideline, air loss should not exceed 3 psi in one minute for a single vehicle or 4 psi in one minute for a combination vehicle. Always follow the current CDL manual for your state, along with the vehicle manufacturer’s and carrier’s procedures. Excessive air loss requires correction before operation.tion.

  Keep the vehicle stationary, wheels chocked, and transmission in neutral. With the engine off and electrical power on, begin with enough air pressure that the low-air warning is not activated. Repeatedly apply and release the service-brake pedal to reduce air pressure while watching the air-pressure gauge(s). The low-air warning light and audible warning should activate before air pressure drops below 60 psi. If the warning fails to activate properly, stop the inspection and report the defect. Do not operate the vehicle until the problem is corrected. Always follow the current CDL manual for your state, along with the vehicle manufacturer’s and carrier’s procedures.

 With the vehicle stationary, wheels chocked, engine off, and electrical power on, continue applying and releasing the service-brake pedal to reduce air pressure. Watch the air-pressure gauge(s) as pressure falls. On a tractor-trailer combination, the tractor-protection valve and parking-brake valve should close or “pop out” when air pressure reaches the manufacturer’s specified range, generally between 20 and 45 psi. This causes the spring brakes to apply automatically. If the valves do not activate as specified, report the defect and do not operate the vehicle until the problem is corrected. Always follow the current CDL manual for your state, along with the vehicle manufacturer’s and carrier’s procedures.

 Rebuild normal operating air pressure. Before any movement, apply the parking brakes, remove the wheel chocks safely, and confirm the test area is clear and level. Fasten your seat belt. Using your carrier’s equipment-specific procedure, select a low gear and gently pull against the applied parking brakes. The brakes should hold the vehicle. Avoid excessive engine power and stop immediately if the vehicle moves. On combinations, complete any prescribed separate tractor and trailer holding checks. Report a failed check and do not depart until corrected.

 With normal operating air pressure, fasten your seat belt and confirm the wheel chocks are removed and the test area is clear. Release the parking brakes and move forward slowly—about 5 mph—in a suitable, level area. Apply the service brakes firmly using the foot pedal. Check for prompt stopping, pulling to either side, unusual pedal feel, or delayed response. Stop and report any abnormal result. Once the test is complete, secure the vehicle with the parking brakes.