How to Successfully Pass the Vehicle Inspection When Getting a CDL in California

Obtaining a Commercial Driver’s License (CDL) in California inevitably includes a practical Vehicle Inspection test. Both federal and California state laws require commercial vehicle drivers to be capable of correctly inspecting the mechanical condition of their truck, bus, or “truck + trailer” combination before going on the road. Below, you will find helpful recommendations and a description of the items inspected in Section 11M of the CDL Handbook (COMMERCIAL DRIVER’S LICENSE HANDBOOK (Supplement for Modernized Version)). This material will help you prepare for the test and understand what you need to show and explain to the examiner.

Why is the Vehicle Inspection test necessary?

1. Safety: Detecting malfunctions and defects helps avoid sudden breakdowns or accidents.

2. Legal requirement: A commercial driver is required to perform a pre-trip inspection in accordance with the Federal Motor Carrier Safety Regulations.

3. Professional skill: Mastering the inspection procedures demonstrates that you are ready to safely and competently operate a large or passenger-carrying vehicle.

Important: During the exam, you will only be asked to check one axle, but you need to be capable of performing such a detailed inspection on all axles.

General Rules and Safety Techniques During Inspection

• Use wheel chocks to prevent the vehicle from rolling.

• Before exiting the cab: always set the parking brake and shift the transmission into neutral.

• Three points of contact: when getting on and off the vehicle, hold on with your hands and place your feet so that you maintain three points of contact. That is, you must be supported by the vehicle with three points simultaneously (two hands and one foot, or two feet and one hand). For example, if you move one hand, the remaining two points (the other hand and a foot) or (both feet) must still be touching a step, grab handle, or part of the metal structure to eliminate the risk of slipping or falling.

• Safety first: any “unsafe action” (for example, forgetting to set the parking brake) may result in failing the test.

Inspection Structure

The Vehicle Inspection test is divided into six main parts:

1. Internal Inspection (All Vehicles)

2. Passenger and School Bus Only

3. School Bus Only

4. Lights Operations Check (All Vehicles)

5. External Inspection (All Vehicles)

6. Combination Vehicles

Below, we will break down what you need to pay special attention to and what to tell the examiner for each section.

Internal Inspection (All Vehicles)

In-Vehicle/Engine Start

This is a check of the main instruments inside the cab and the correct starting of the engine.

1. Dashboard Indicators

   • Left/Right turn signal indicator

   • Four-way emergency indicator

   • High beam headlight indicator

   • ABS/DEF (if equipped)

   • Make sure all indicators work when you turn on the corresponding systems.

2. Emergency Equipment

   • Three red reflective triangles.

   • Spare fuses (or mention that the vehicle uses circuit breakers).

   • A fire extinguisher (in working condition and properly secured).

3. Windshield and Mirrors/Cameras

   • The windshield is free of cracks and any stickers that obstruct the driver’s view.

   • Mirrors/cameras are clean and properly adjusted.

4. Wipers/Washer

   • Wipers fit snugly against the glass and operate without jerking.

   • The washer sprays fluid.

5. Heater/Defroster

   • Turn them on and check that the heater and windshield defroster are working.

6. Horn(s)

   • Give a brief press to ensure the electric or air horn works.

7. Parking and Trailer Brake Check

   • Parking Brake Check: set the parking brake, gently try to move forward at low speed, and make sure the vehicle does not move.

   • Trailer Brake Check (for combinations): similarly, but with the trailer brake applied while the parking brake is released.

8. Service Brake Check

   • Accelerate to 5 mph, apply the service (foot) brake, and make sure the vehicle does not pull to either side and stops smoothly.

Air Brake or Hydraulic Brake Check

If you have Air Brakes:

1. Air Gauge & Governor Cutoff: Pressure should rise to 120–140 psi.

2. Air Leakage Rate Test: Shut off the engine, turn on ignition, and hold the brake pedal. The allowable pressure drop is up to 3 psi in one minute (for a single vehicle) or 4 psi (for a combination).

3. Air Warning Device Test: When pumping the brake pedal, low-pressure warning devices should activate before pressure drops below 55 psi.

4. Emergency Brake Test: With further pressure release, the parking/emergency brake valve “pops out” at 20–45 psi.

If you have Hydraulic Brakes:

• Make sure warning indicators and systems work as intended.

• With the engine off (in PARK), press the brake pedal three times and hold it. The pedal should not continue to move downward.

• If there is a hydraulic booster or power assist, check it according to the manufacturer’s instructions.

Passenger and School Bus Only

1. Passenger Entry & Lift

   • Entry/exit doors should open and close smoothly, and handrails must be securely attached.

   • Steps should be clean with no loose or worn treads.

   • If equipped with a wheelchair lift, check that it works and there are no leaks.

2. Emergency Exits

   • All emergency exits (doors, windows, roof hatches) must be labeled.

   • At least one exit must be demonstrated as fully operational and undamaged.

   • With the ignition on, ensure the emergency exit warning alarms work.

3. Passenger Seating

   • Seat mounting is not damaged and securely attached to the floor.

   • No broken or loose seat frames.

4. Passenger Monitoring Devices

   • All internal and external mirrors for passenger visibility are intact and clean.

   • If cameras are installed, ensure the monitor is working and properly adjusted.

School Bus Only

1. Student Lights (front and back)

   • Check the strobe light (if equipped).

   • Alternating amber lights and alternating red lights in front and rear.

   • Corresponding dash indicators should illuminate.

2. Stop Arm(s) & Safety Arm

   • The stop arm(s) should fully extend, with functioning lights, and be securely mounted.

   • The safety arm (if equipped) should also extend properly.

3. First Aid & Body Fluid Kits

   • First aid kit and body fluid cleanup kit must be present, with factory seal unbroken.

Lights Operations Check (All Vehicles)

• Ensure that all external lights (turn signals, four-way flashers, clearance lights, low/high beams, brake lights, taillights) work.

• For a tractor-trailer combination, you only need to check the rear trailer lights, but be ready if you’re asked about others.

• Usually, the examiner will help by looking outside while you turn the lights on and off. However, you must state which light you’re checking to receive credit.

External Inspection (All Vehicles)

Front/Engine Area

1. Lenses

   • Headlight lenses are of the proper color, clean, not cracked.

2. Critical Fluid Levels

   • Engine oil, coolant, power steering fluid, and brake fluid (for hydraulics).

   • Make sure each level is within “add” and “full.”

3. Fluid and Air Leaks

   • Look for any puddles under the vehicle.

   • Check hoses and connections for leaks.

4. Steering System

   • The steering gearbox is not leaking; mounting bolts are secure.

   • Linkages, joints, and rods are not excessively loose or damaged.

Axle Inspection (example: Steering Axle)

(On the test, they may ask you to check any axle, but the process is similar.)

1. Tires

   • Use a tire gauge for proper inflation (kicking tires is not acceptable).

   • Tread depth: at least 4/32” on the steering axle and 2/32” on other axles.

   • No cuts or bulges, valve caps intact.

2. Rims/Wheels

   • No cracks, not bent, no illegal welds.

   • No rust streaks indicating looseness.

3. Lug Nuts

   • All present, none loose, no cracks in the studs.

4. Springs, Air Bags & Shocks

   • No broken, missing, or shifted leaf springs.

   • Air ride suspension is not leaking; shock absorbers not leaking fluid.

   • Vehicle should sit level.

5. Brake Lines & Leaks

   • No cracks, worn hoses, or leaks.

   • Connections must be secure.

6. Brake Contaminates

   • If visible, ensure there’s no grease, oil, or other contaminants on drums/rotors.

Side of Vehicle

• Check side lights and reflectors for correct color, no damage.

• Side mirrors/cameras are clean, intact, and firmly mounted.

• Batteries (if visible) are secure, no excessive corrosion.

• Fuel tanks have secure caps, no leaks, properly mounted.

• Frame has no cracks, broken welds, or holes.

Rear of Vehicle or Trailer

• Check the rear lights and reflectors: correct color, no cracks, functioning.

• For a combination, verify trailer’s rear lights.

Combination Vehicles

If you have a tractor-trailer or truck-trailer setup, you must also check:

1. Air & Electric Lines/Connectors

   • Hoses are not worn or leaking; connectors fit securely.

   • Wires are not damaged; insulation is intact.

2. Coupling System

   • Fifth Wheel (for a tractor-semitrailer): proper lubrication, no cracks, locking jaws fully around the kingpin. Kingpin and apron are not deformed.

   • Pintle Hook (for drawbar trailer): the hook is securely attached to the frame, no cracks or excessive play. The drawbar ring on the trailer tongue is not bent or cracked.

   • Locking & Safety Devices: all latches, safety pins, and chains (if present) are in place and undamaged.

3. Landing Gear

   • Fully raised, handle secured, no bending in the supports.

   • The tractor’s frame should clear the landing gear during turns.

4. Reflective Tape

   • On the trailer sides and rear, if required by law.

Practical Tips for Passing the Test

1. Practice in advance: Many people fail because they don’t remember the sequence and can’t quickly articulate what they are checking and why.

2. Follow the examiner’s instructions: If anything is unclear, feel free to ask for clarification.

3. Name, point, and explain: The examiner wants to see you understand why each detail is important for safety.

4. Don’t make extra marks on the checklist before the test: You can use only a clean version of the CDL Vehicle Inspection checklist.

5. Safety above all: Any action that compromises safety (e.g., forgetting to set the parking brake) may result in an automatic fail.

What’s Next?

After successfully passing the Vehicle Inspection Test, you will move on to the Basic Control Skills test (maneuvering) and then the Road Driving test. However, first the examiners must ensure you can properly and safely maintain your truck or bus.

Conclusion

Carrying out a thorough and correct pre-trip inspection is one of the most important tasks of a commercial driver. We hope this guide helps you understand the main points of the CDL Vehicle Inspection in California. Take time to practice, learn the sequence and requirements, and you will likely pass the test successfully and get your CDL!