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CDL Pre-Trip Inspection External Cab

Last updated on September 27, 2022

The following is a list of items that the driver must check during the CDL pre trip inspection external cab, including passenger bus/tractor-trailer.

CDL Pre Trip Inspection External Cab (Passenger Bus/Truck/Tractor)



  • Check that the steering box is securely mounted and not leaking. Look for any missing nuts, bolts, and cotter keys.
  • Check for power steering fluid leaks or damage to power steering hoses.

Steering Linkage

  • See that connecting links, arms, and rods from the steering box to the wheel are not worn or cracked.
  • Check that joints and sockets are not worn or loose and that there are no missing nuts, bolts, or cotter keys.



  • Look for missing, shifted, cracked, or broken leaf springs.
  • Look for broken or distorted coil springs.
  • If the vehicle is equipped with torsion bars, torque arms, or other types of suspension components, check that they are not damaged and are mounted securely.
  • Air ride suspension should be checked for damage and leaks.


  • Look for cracked or broken spring hangers, missing or damaged bushings, and broken, loose, or missing bolts, U-bolts or other axle mounting parts. (The mounts should be checked at each point where they are secured to the vehicle frame and axle(s)). This includes mounts used for air ride systems.

Shock Absorbers

  • See that shock absorbers are secure and that there are no leaks.


Slack Adjusters

  • Look for broken, loose, or missing parts.
  • The angle between the push rod and adjuster arm should be a little over 90 degrees when the brakes are released, and not less than 90 degrees when the brakes are applied.
  • When pulled by hand, the brake rod should not move more than one inch (with the brakes released).

Brake Chambers

  • See that brake chambers are not leaking, cracked, or dented and are mounted securely.

Brake Hoses/Lines

  • Look for cracked, worn, or leaking hoses, lines, and couplings.

Drum Brake or Rotor

  • Check for cracks, dents, or holes. Also check for loose or missing bolts.
  • Brake linings or pads (where visible) should not be worn dangerously thin.

Brake Linings

  • On some brake drums, there are openings where the brake linings can be seen from outside the drum. For this type of drum, check that a visible amount of brake lining is showing.



  • Check for damaged or bent rims.
  • Rims cannot have welding repairs.


The following items must be inspected on every tire:

  • Tread depth: Check for minimum tread depth (4/32 on steering axle tires, 2/32 on all other tires).
  • Tire condition: Check that tread is evenly worn and look for cuts or other damage to tread or sidewalls. Also, make sure valve caps and stems are not missing, broken, or damaged.
  • Tire inflation: Check for proper inflation by using a tire gauge, or inflation by striking tires with a mallet or other similar device.

Hub Oil Seals/Axle Seals

  • See that hub oil/grease seals and axle seals are not leaking and, if wheel has a sight glass, oil level is adequate.

Lug Nuts

  • Check that all lug nuts are present, free of cracks and distortions, and show no signs of looseness such as rust trails or shiny threads.
  • Make sure all bolt holes are not cracked or distorted.


  • If equipped, check that spacers are not bent, damaged, or rusted through.
  • Spacers should be evenly centered, with the dual wheels and tires evenly separated.



  • Check that door(s) are not damaged and that they open and close properly from the outside.
  • Hinges should be secure with seals intact.
  • Check that mirror(s) and mirror brackets are not damaged and are mounted securely with no loose fittings.

Fuel Tank

  • Check that tank(s) are secure, cap(s) are tight, and there are no leaks from tank(s) or lines.


  • Wherever located, see that battery(s) are secure, connections are tight, and cell caps are present.
  • Battery connections should not show signs of excessive corrosion.
  • Battery box and cover or door must be secure.

Drive Shaft

  • See that drive shaft is not bent or cracked.
  • Couplings should be secure and free of foreign objects.

Exhaust System

  • Check system for damage and signs of leaks such as rust or carbon soot.
  • System should be connected tightly and mounted securely.


  • Look for cracks, broken welds, holes or other damage to the longitudinal frame members, cross members, box, and floor.


Splash Guards

  • If equipped, check that splash guards or mud flaps are not damaged and are mounted securely.


  • Check that doors and hinges are not damaged and that they open, close, and latch properly from the outside, if equipped.
  • Ties, straps, chains, and binders must also be secure.
  • If equipped with a cargo lift, look for leaking, damaged or missing parts.
  • Lift must be fully retracted and latched securely.


Air/Electric Lines

  • Listen for air leaks. Check that air hoses and electrical lines are not cut, chafed, spliced, or worn (steel braid should not show through).
  • Make sure air and electrical lines are not tangled, pinched, or dragging against tractor parts.


  • Make sure the catwalk is solid, clear of objects, and securely bolted to tractor frame.

Mounting Bolts

  • Look for loose or missing mounting brackets, clamps, bolts, or nuts. Both the fifth wheel and the slide mounting must be solidly attached.
  • On other types of coupling systems (i.e., ball hitch, pintle hook, tow bars, tow bar eye, etc.), inspect all coupling components and mounting brackets for missing or broken parts.

Locking Jaws

  • Look into fifth wheel gap and check that locking jaws are fully closed around the kingpin.
  • On other types of coupling systems (i.e., ball hitch, pintle hook, etc.), inspect the locking mechanism for missing or broken parts and make sure it is locked securely. If present, safety cables or chains must be secure and free of kinks and excessive slack (locking pin, safety latch, chains and brackets).

Platform (fifth wheel)

  • Check for cracks or breaks in the platform structure which supports the fifth wheel skid plate.

Release Arm (fifth wheel)

  • If equipped, make sure the release arm is in the engaged position and the safety latch is in place.


  • Check that the kingpin is not bent.
  • Make sure the visible part of the apron is not bent, cracked, or broken.
  • Check that the trailer is laying flat on the fifth wheel skid plate (no gap).

Locking Pins (fifth wheel)

  • If equipped, look for loose or missing pins in the slide mechanism of the sliding fifth wheel. If air powered, check for leaks.
  • Make sure locking pins are fully engaged.
  • Check that the fifth wheel is positioned properly so the tractor frame will clear the landing gear and the tractor will not strike the trailer during turns.

More information on the CDL pre trip inspection external cab, including passenger bus/tractor-trailer can be found at 49CFR383.113.

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