Commercial driver’s license (CDL) knowledge tests · California DMV
Vehicle inspection
Questions and answers
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What is the most important reason to inspect your vehicle?
Safety, for yourself and other road users
Safety comes first. Saving time and money on breakdowns is a further benefit.
Section 2 · 2.1.1 – Why Inspect ↗ -
A federal or state inspector judges your vehicle to be unsafe. What happens?
It is put out of service until it is fixed
An unsafe vehicle is placed out of service until the problem is repaired.
Section 2 · 2.1.1 – Why Inspect ↗ -
Once you get behind the wheel, who is responsible for the safe operation of the vehicle?
You, the driver
The driver, not the mechanic, is responsible for safe operation.
Section 2 · 2.1.2 – Types of Vehicle Inspections ↗ -
The last inspection report lists defects that affect safety. What must the motor carrier do?
Repair them and certify on the report that repairs were made or were unnecessary
The carrier repairs safety items and certifies on the report that the repairs were made or were not needed.
Section 2 · 2.1.2 – Types of Vehicle Inspections ↗ -
When do you sign the previous driver’s inspection report?
When defects were noted and have been certified as repaired or not needing repair
You sign only if defects were noted and certified to be repaired or not to need repair.
Section 2 · 2.1.5 – 7-Step Inspection Method ↗ -
Which items should you check each time you stop during a trip?
Tires, wheels and rims, brakes, lights, connections to the trailer, coupling devices, and cargo securement
The critical stop checks are tires, wheels, rims, brakes, lights and reflectors, trailer connections, coupling devices, and cargo securement.
Section 2 · 2.1.2 – Types of Vehicle Inspections ↗ -
How should you watch for trouble while you are driving?
Watch the gauges and use your senses to look, listen, smell, and feel
During a trip, watch the gauges for signs of trouble and use your senses.
Section 2 · 2.1.2 – Types of Vehicle Inspections ↗ -
When should an after-trip inspection be done?
At the end of the trip, day, or tour of duty on each vehicle you operated
The after-trip inspection covers each vehicle you operated, at the end of the trip, day, or tour of duty.
Section 2 · 2.1.2 – Types of Vehicle Inspections ↗ -
What is the minimum tread depth in every major groove of the front tires?
4/32 inch
Front tires need at least 4/32 inch of tread in every major groove.
Section 2 · 2.1.3 – What to Look For ↗ -
What is the minimum tread depth on tires that are not on the front axle?
2/32 inch
Tires other than the front ones need 2/32 inch.
Section 2 · 2.1.3 – What to Look For ↗ -
You measure 3/32 inch of tread on a tire. Where on the vehicle is that tire acceptable?
On a rear axle but not on the front
Front tires need 4/32 inch, so 3/32 inch is too little there. Other tires need only 2/32 inch.
Section 2 · 2.1.3 – What to Look For ↗ -
Which tire condition is a problem?
Radial and bias-ply tires used together
Mixing radial and bias-ply tires is a defect, as are mismatched sizes and cut or cracked valve stems.
Section 2 · 2.1.3 – What to Look For ↗ -
On which wheels of a bus are regrooved, recapped, or retreaded tires prohibited?
The front wheels
These tires may not be used on the front wheels of a bus.
Section 2 · 2.1.3 – What to Look For ↗ -
You see fabric showing through the sidewall of a tire. Is the tire acceptable?
No, fabric must not show through the tread or sidewall
No fabric should show through the tread or the sidewall.
Section 2 · 2.1.3 – What to Look For ↗ -
What can rust around the wheel nuts mean?
The nuts may be loose
Rust around wheel nuts can be a sign of looseness, so check their tightness.
Section 2 · 2.1.3 – What to Look For ↗ -
You have just had a tire changed. What should you do a short while later?
Stop and recheck the tightness of the nuts
After a tire change, stop after a short distance and recheck the nuts.
Section 2 · 2.1.3 – What to Look For ↗ -
What does the handbook say about wheels or rims that have had welding repairs?
They are not safe
Wheels or rims with welding repairs are not safe.
Section 2 · 2.1.3 – What to Look For ↗ -
Which is a brake drum or shoe defect?
Shoes or pads with oil, grease, or brake fluid on them
Look for cracked drums, contaminated shoes or pads, and shoes that are worn thin, missing, or broken.
Section 2 · 2.1.3 – What to Look For ↗ -
How much steering wheel play can make it hard to steer?
More than 10 degrees
Play of more than 10 degrees is a steering defect.
Section 2 · 2.1.3 – What to Look For ↗ -
On a 20 inch steering wheel, about how much movement at the rim equals 10 degrees of play?
About 2 inches
Ten degrees is roughly 2 inches of movement at the rim of a 20 inch wheel.
Section 2 · 2.1.3 – What to Look For ↗ -
Your vehicle has power steering. What should you check on it?
Hoses, pumps, fluid level, and leaks
With power steering, check the hoses, pumps, and fluid level, and look for leaks.
Section 2 · 2.1.3 – What to Look For ↗ -
What does the suspension system do?
It holds up the vehicle and its load and keeps the axles in place
Because the suspension supports the load and positions the axles, broken parts can be extremely dangerous.
Section 2 · 2.1.3 – What to Look For ↗ -
What share of missing leaves in a leaf spring will put the vehicle out of service?
1/4 or more
A quarter or more of the leaves missing puts the vehicle out of service, though any defect could be dangerous.
Section 2 · 2.1.3 – What to Look For ↗ -
Which of these is a suspension system defect?
Leaking shock absorbers
Suspension defects include leaking shock absorbers, damaged spring hangers, torque rods, u-bolts, and leaking air suspension.
Section 2 · 2.1.3 – What to Look For ↗ -
Why is a broken exhaust system dangerous?
It can let poison fumes into the cab or sleeper berth
A broken exhaust can leak poison fumes into the cab or sleeper berth.
Section 2 · 2.1.3 – What to Look For ↗ -
Which exhaust condition is a defect?
Exhaust parts rubbing against fuel system parts or tires
Exhaust parts must not rub against fuel system parts, tires, or other moving parts, and must not leak.
Section 2 · 2.1.3 – What to Look For ↗ -
Which three kinds of emergency equipment must a vehicle carry?
Fire extinguisher, spare electrical fuses, and warning devices for parked vehicles
Required equipment is a fire extinguisher, spare fuses unless the vehicle has circuit breakers, and warning devices.
Section 2 · 2.1.3 – What to Look For ↗ -
When are spare electrical fuses NOT required?
When the vehicle is equipped with circuit breakers
Spare fuses are required unless the vehicle uses circuit breakers.
Section 2 · 2.1.3 – What to Look For ↗ -
How many red reflective warning triangles should you carry?
3
Carry 3 red reflective triangles, or the alternatives of 6 fuses or 3 liquid burning flares.
Section 2 · 2.1.3 – What to Look For ↗ -
Before each trip in a truck, what must you make sure of about the cargo?
The truck is not overloaded and the cargo is balanced and secured
Check that the truck is not overloaded and the cargo is balanced and secured.
Section 2 · 2.1.4 – CDL Vehicle Inspection Test ↗ -
Your cargo contains hazardous materials. What extra thing must you inspect?
Proper papers and placarding
With HazMat on board, inspect for proper papers and placarding.
Section 2 · 2.1.4 – CDL Vehicle Inspection Test ↗ -
During the vehicle inspection test, how do you show the examiner each item?
Point to or touch it, name it, and explain why you inspect it
You must point to or touch each item, name it, and explain to the examiner why you are inspecting it.
Section 2 · 2.1.4 – CDL Vehicle Inspection Test ↗ -
Why should you do the vehicle inspection the same way every time?
You learn all the steps and are less likely to forget something
A fixed routine helps you learn the steps and miss nothing.
Section 2 · 2.1.5 – 7-Step Inspection Method ↗ -
What should you look for as you walk up to the vehicle?
Damage, leaning to one side, fresh leaks underneath, and hazards around it
Note the general condition, look underneath for fresh oil, coolant, grease, or fuel leaks, and check the area for hazards.
Section 2 · 2.1.5 – 7-Step Inspection Method ↗ -
Before checking the engine compartment, what should you confirm?
The parking brakes are on or the wheels are chocked
Check that the parking brakes are on and/or the wheels are chocked.
Section 2 · 2.1.5 – 7-Step Inspection Method ↗ -
Which fluid level check may need the engine to be running?
Automatic transmission fluid
Checking the automatic transmission fluid level may require the engine to be running.
Section 2 · 2.1.5 – 7-Step Inspection Method ↗ -
In the engine compartment, what do you check the belts for?
Tightness and excessive wear
Check the alternator, water pump, and air compressor belts for tightness and wear, and know how much give each should have.
Section 2 · 2.1.5 – 7-Step Inspection Method ↗ -
What do you look for on the electrical wiring in the engine compartment?
Cracks and wear in the insulation
The wiring insulation is checked for cracks and wear.
Section 2 · 2.1.5 – 7-Step Inspection Method ↗ -
Before starting the engine with a manual transmission, where should the gearshift be?
In Neutral
Make sure the parking brake is on and put the gearshift in Neutral, or Park for an automatic.
Section 2 · 2.1.5 – 7-Step Inspection Method ↗ -
You start the engine and the ABS light on the dash comes on and stays on. What does this mean?
The ABS is not working properly
The light should come on and then go off. If it stays on, the ABS is not working properly.
Section 2 · 2.1.5 – 7-Step Inspection Method ↗ -
On a trailer, which light staying on shows that the trailer ABS is not working properly?
The yellow light on the left rear of the trailer
For trailers, the ABS indicator is a yellow light on the left rear.
Section 2 · 2.1.5 – 7-Step Inspection Method ↗ -
How soon after the engine starts should oil pressure come up to normal?
Within seconds
Oil pressure should rise to normal within seconds of starting.
Section 2 · 2.1.5 – 7-Step Inspection Method ↗ -
The oil pressure gauge shows low, dropping, or fluctuating pressure. What should you do?
Stop immediately
Without oil the engine can be destroyed rapidly, so stop at once.
Section 2 · 2.1.5 – 7-Step Inspection Method ↗ -
How quickly should air pressure build from 50 to 90 psi?
Within 3 minutes
The pressure should build from 50 to 90 psi within 3 minutes.
Section 2 · 2.1.5 – 7-Step Inspection Method ↗ -
What should the coolant temperature gauge do after the engine is started?
Begin a gradual rise to the normal operating range
Coolant and engine oil temperatures should rise gradually to the normal operating range.
Section 2 · 2.1.5 – 7-Step Inspection Method ↗ -
After starting the engine, what should the oil, coolant, and charging circuit warning lights do?
Go out right away
These warning lights and the ABS lights should go out right away.
Section 2 · 2.1.5 – 7-Step Inspection Method ↗ -
What do you inspect mirrors and the windshield for?
Cracks, dirt, illegal stickers, or other things that block your view
Look for anything that obstructs clear vision, then clean and adjust as needed.
Section 2 · 2.1.5 – 7-Step Inspection Method ↗ -
Which of these is an optional item, not required safety equipment?
Tire changing equipment
Optional items include chains, tire changing equipment, a list of emergency phone numbers, and an accident reporting kit.
Section 2 · 2.1.5 – 7-Step Inspection Method ↗ -
What do you check on the safety belt?
It is securely mounted, adjusts and latches properly, and is not ripped or frayed
The belt must be securely mounted, adjust and latch properly, and show no rips or fraying.
Section 2 · 2.1.5 – 7-Step Inspection Method ↗ -
In Step 4 you turn off the engine to check the lights. What do you do with the key?
Take it with you
Set the parking brake, turn off the engine, and take the key with you.
Section 2 · 2.1.5 – 7-Step Inspection Method ↗ -
Which lights do you switch on before getting out to begin the Step 4 light check?
Low beam headlights and 4-way emergency flashers
Turn on the low beams and the 4-way flashers, then check them from the front.
Section 2 · 2.1.5 – 7-Step Inspection Method ↗ -
How do you test rust-streaked lug nuts during the walk around?
With a wrench, since the streaks indicate looseness
Rust-streaked lug nuts suggest looseness and are tested with a wrench.
Section 2 · 2.1.5 – 7-Step Inspection Method ↗ -
How do you check the steering mechanism for looseness during the walk around?
Grab the steering mechanism and test it
You must grab the steering mechanism to test for looseness.
Section 2 · 2.1.5 – 7-Step Inspection Method ↗ -
What color should clearance and identification lights be at the front of the vehicle?
Amber
Front parking, clearance, and identification lights and reflectors are amber.
Section 2 · 2.1.5 – 7-Step Inspection Method ↗ -
What colors are acceptable for a turn signal that faces forward?
Amber or white
Front-facing turn signals are amber or white.
Section 2 · 2.1.5 – 7-Step Inspection Method ↗ -
What color must taillights and rear clearance lights be?
Red
Lights and reflectors at the rear are red.
Section 2 · 2.1.5 – 7-Step Inspection Method ↗ -
What colors are acceptable for rear turn signals?
Red, yellow, or amber
Rear turn signals may be red, yellow, or amber.
Section 2 · 2.1.5 – 7-Step Inspection Method ↗ -
What color are side-marker lights that are not at the rear?
Amber
Side-marker lights and reflectors are red at the rear and amber elsewhere.
Section 2 · 2.1.5 – 7-Step Inspection Method ↗ -
On a cab-over-engine truck, what must you check about the cab locks?
The primary and secondary safety cab locks are engaged
On a cab-over-engine design, both the primary and secondary safety cab locks must be engaged.
Section 2 · 2.1.5 – 7-Step Inspection Method ↗ -
What do you check wheel bearings and seals for?
Leaks
Wheel bearings and seals should not be leaking.
Section 2 · 2.1.5 – 7-Step Inspection Method ↗ -
Which is correct about dual tires on the rear?
They must not rub each other and nothing may be stuck between them
Rear tires must be properly inflated, the same type and size, not rubbing, with nothing stuck between them.
Section 2 · 2.1.5 – 7-Step Inspection Method ↗ -
A tarp covers your load. How must it be secured?
So it cannot tear, billow, or block the mirrors and rear lights
A canvas or tarp must be secured to prevent tearing, billowing, and blocking of mirrors or rear lights.
Section 2 · 2.1.5 – 7-Step Inspection Method ↗ -
Your load is oversize. What must be in your possession?
All required permits
With an oversize load, the signs must be properly mounted and all required permits must be with the driver.
Section 2 · 2.1.5 – 7-Step Inspection Method ↗ -
What do you check about the splash guards?
They are present, undamaged, fastened, not dragging, and not rubbing the tires
Splash guards must be present, not damaged, properly fastened, not dragging on the ground, and not rubbing the tires.
Section 2 · 2.1.5 – 7-Step Inspection Method ↗ -
Which battery check does not apply to a maintenance-free battery?
Checking that the fluid is at the proper level
Fluid level, cell caps, and cap vents are checked except on maintenance-free batteries.
Section 2 · 2.1.5 – 7-Step Inspection Method ↗ -
How can you turn on the stop lights to check them when you are alone?
Apply the trailer hand brake
Apply the trailer hand brake, or have a helper press the brake pedal.
Section 2 · 2.1.5 – 7-Step Inspection Method ↗ -
How must the brake light, turn signal, and 4-way flasher functions be checked?
Separately
Each of these functions must be checked on its own.
Section 2 · 2.1.5 – 7-Step Inspection Method ↗ -
Why should you secure loose articles in the cab?
They might interfere with the controls or hit you in an accident
Loose items can get in the way of the controls or strike you in a crash.
Section 2 · 2.1.5 – 7-Step Inspection Method ↗ -
How do you test hydraulic brakes for leaks?
Pump the pedal 3 times, then press firmly and hold for 5 seconds
Pump the brake pedal 3 times, apply firm pressure, and hold for 5 seconds.
Section 2 · 2.1.5 – 7-Step Inspection Method ↗ -
During the hydraulic brake leak test the pedal slowly sinks while you hold it. What does this tell you?
There may be a leak or other problem, so get it fixed before driving
The pedal should not move. If it does, have the system fixed before you drive.
Section 2 · 2.1.5 – 7-Step Inspection Method ↗ -
How do you test the parking brake?
Set it, put the vehicle in a low gear, and gently pull forward against it
With the parking brake set, gently pull forward in a low gear to see that it holds.
Section 2 · 2.1.5 – 7-Step Inspection Method ↗ -
At about what speed do you test the stopping action of the service brake?
About 5 mph
Drive at about 5 mph and push the brake pedal firmly.
Section 2 · 2.1.5 – 7-Step Inspection Method ↗ -
During the service brake test the vehicle pulls to one side. What can this mean?
Brake trouble
Pulling to one side, an unusual pedal feel, or delayed stopping can all mean brake trouble.
Section 2 · 2.1.5 – 7-Step Inspection Method ↗ -
You find something unsafe during the vehicle inspection. What should you do?
Get it fixed, because the law forbids operating an unsafe vehicle
Federal and state laws forbid operating an unsafe vehicle.
Section 2 · 2.1.5 – 7-Step Inspection Method ↗ -
Within how many miles of starting a trip must a truck driver inspect the securement of the cargo?
Within the first 50 miles
The first cargo securement check is due within the first 50 miles.
Section 2 · 2.1.6 – Inspection During a Trip ↗ -
After the first check, how often must cargo securement be inspected?
Every 150 miles or every 3 hours, whichever comes first
Recheck every 150 miles or every 3 hours, whichever comes first.
Section 2 · 2.1.6 – Inspection During a Trip ↗ -
You checked your cargo 2 hours ago and have driven 150 miles since. Is another check due?
Yes, because 150 miles came first
The check is due at 150 miles or 3 hours, whichever is reached first.
Section 2 · 2.1.6 – Inspection During a Trip ↗ -
Which of these should you check regularly while driving?
Gauges, mirrors, tires, and cargo
During a trip check instruments, gauges, mirrors, tires, cargo and covers, and lights.
Section 2 · 2.1.6 – Inspection During a Trip ↗ -
What belongs in your written after-trip report?
Anything affecting safety or possibly leading to a mechanical breakdown
Report anything that affects safety or could lead to a breakdown.
Section 2 · 2.1.7 – After-Trip Inspection and Report ↗ -
How long should a copy of your vehicle inspection report stay in the vehicle?
1 day
Keep a copy in the vehicle for 1 day so the next driver can learn about the problems you found.
Section 2 · 2.1.7 – After-Trip Inspection and Report ↗
Questions and answers by topic
- Licenses, endorsements and tests105
- Disqualifications and state rules110
- Basic control and shifting gears47
- Seeing and communicating46
- Controlling your speed62
- Managing space40
- Seeing hazards49
- Distracted and Aggressive Driving71
- Night, Fog, Winter and Hot Weather124
- Railroad Crossings and Mountain Driving65
- Emergencies, ABS and Skids102
- Accident Procedures and Fires49
- Alcohol, Drugs and Illness41
- Hazardous Materials Rules for All Drivers42
- Transporting Cargo Safely79
- Bus Inspection, Loading and Hazardous Materials74
- Driving a Bus: Stops, Crossings and Prohibited Practices56
- Air Brake Parts: Compressor, Tanks and Foundation Brakes52
- Warnings, Spring Brakes, ABS and Dual Systems59
- Inspecting Air Brake Systems61
- Using Air Brakes51
- Driving Combination Vehicles Safely50
- Combination Vehicle Air Brakes and ABS59
- Coupling and Uncoupling63
- Inspecting a Combination Vehicle24
- Pulling Double and Triple Trailers16
- Coupling, Inspecting and Brake Checks for Doubles34
- Tank Vehicles62
- HazMat basics and who does what48
- Hazard classes, labels and lists64
- Shipping papers and package markings49
- Placards and placard tables40
- Loading and unloading HazMat58
- Bulk packaging and tanks30
- HazMat driving and parking rules72
- HazMat emergencies and reporting60
- Danger zones and mirrors34
- Loading and unloading students47
- Emergency exit and evacuation34
- Railroad-highway crossings40
- Student management, ABS and special situations47