Your eyelids feel heavy and your truck has drifted toward the lane edge twice. What should you do?
Correct answer: Stop at the nearest safe place and get needed rest.
These are warning signs of fatigue. Do not wait for a crash or a planned stop to act. Get to a safe stopping place and rest before continuing; cab stimulation is not a substitute for sleep.
Source: South Carolina Commercial Driver's License Manual, posted 179-page PDF, body version March 2025; 2.11.2 Driver Factors / fatigue and vision; printed page 2-27, physical PDF page 59; reviewed September 21, 2026. ↗
A driver cannot recall the last several miles and has missed an exit. What is the safest interpretation?
Correct answer: Fatigue may be affecting awareness and requires a safe stop.
Missing recent driving memories or signs can be a fatigue warning. The driver should safely stop and address the need for rest, not use another vehicle as a substitute for alertness.
Source: South Carolina Commercial Driver's License Manual, posted 179-page PDF, body version March 2025; 2.11.2 Driver Factors / fatigue and vision; printed page 2-27, physical PDF page 59; reviewed September 21, 2026. ↗
A tired driver feels more awake after coffee and cold air from a window. What should the driver understand?
Correct answer: Feeling stimulated does not replace the sleep the driver needs.
Temporary stimulation is not a reliable solution for fatigue. Plan adequate rest and stop safely when drowsy instead of treating a short-lived feeling of alertness as proof of safe driving ability.
Source: South Carolina Commercial Driver's License Manual, posted 179-page PDF, body version March 2025; 2.11.2 Driver Factors / maintaining alertness; printed page 2-28, physical PDF page 60; reviewed September 21, 2026. ↗
Why should a driver avoid darkly tinted glasses when driving at night?
Correct answer: They reduce the light available for seeing hazards.
Night driving already offers less visual information. Dark lenses reduce available light further. Do not try to solve glare by making the whole scene darker.
Source: South Carolina Commercial Driver's License Manual, posted 179-page PDF, body version March 2025; 2.11.2 Driver Factors / fatigue and vision; printed page 2-27, physical PDF page 59; reviewed September 21, 2026. ↗
Headlight glare seems worse through a windshield with an oily film inside. What should you do before another night trip?
Correct answer: Clean both the inside and outside glass surfaces.
Dirt and film can scatter light and worsen glare. Cleaning inside and outside glass, along with mirrors and lights, helps preserve the limited visibility available at night.
Source: South Carolina Commercial Driver's License Manual, posted 179-page PDF, body version March 2025; 2.11.4 Vehicle Factors / windshield and mirrors; printed page 2-29, physical PDF page 61; reviewed September 21, 2026. ↗
How should interior cab lighting be managed during night driving?
Correct answer: Keep it low enough to avoid glare while instruments remain readable.
Bright interior lighting can interfere with outside vision. Keep instruments readable without unnecessary cab glare, and maintain attention to the road.
Source: South Carolina Commercial Driver's License Manual, posted 179-page PDF, body version March 2025; 2.11.5 Night Driving Procedures; printed page 2-29, physical PDF page 61; reviewed September 21, 2026. ↗
A truck's headlamps are dirty and one is poorly aimed. What is the right response before driving at night?
Correct answer: Clean the lamps and have their aim corrected.
Dirty or misaligned headlamps reduce useful road illumination and may create glare for others. Correct their condition rather than compensating with unsafe following or inappropriate beam use.
Source: South Carolina Commercial Driver's License Manual, posted 179-page PDF, body version March 2025; 2.11.4 Vehicle Factors / headlights; printed page 2-28, physical PDF page 60; reviewed September 21, 2026. ↗
Oncoming high beams make it hard to see. Where should you direct your attention?
Correct answer: Toward the right side of your lane, without staring at the lights.
Avoid looking directly into bright oncoming lamps. Use the right side of your lane as a guide while continuing to monitor your path and adjusting speed for the visibility you actually have.
Source: South Carolina Commercial Driver's License Manual, posted 179-page PDF, body version March 2025; 2.11.5 Night Driving Procedures; printed page 2-29, physical PDF page 61; reviewed September 21, 2026. ↗
Which headlight setting generally gives better visibility in fog?
Correct answer: Low beams, because high beams reflect more light back toward you.
High beams reflect off fog and can worsen the driver's view. Use low beams and an appropriate reduced speed; better lighting does not remove the need for a safe visibility margin.
Source: South Carolina Commercial Driver's License Manual, posted 179-page PDF, body version March 2025; 2.12 Driving in Fog; printed page 2-29, physical PDF page 61; reviewed September 21, 2026. ↗
Why is following the vehicle ahead's taillights an unreliable way to navigate dense fog?
Correct answer: That vehicle may stop or leave the roadway without you realizing it.
Do not blindly follow lights through fog. The other vehicle may be stopped or may have left the roadway. Maintain your own awareness of the road and a safe distance.
Source: South Carolina Commercial Driver's License Manual, posted 179-page PDF, body version March 2025; 2.12 Driving in Fog; printed page 2-29, physical PDF page 61; reviewed September 21, 2026. ↗
Before entering a stretch of very dense fog, you can safely reach a truck stop. What is the safer option if visibility is inadequate?
Correct answer: Wait at the truck stop until conditions improve.
When possible, avoid driving in dense fog by waiting in a safe location such as a truck stop or rest area. A roadside stop can expose the truck to vehicles whose drivers cannot see it in time.
Source: South Carolina Commercial Driver's License Manual, posted 179-page PDF, body version March 2025; 2.12 Driving in Fog; printed page 2-29, physical PDF page 61; reviewed September 21, 2026. ↗
Which preparation helps keep the windshield usable in freezing conditions?
Correct answer: Check the defroster, wipers and freeze-protected washer supply.
Winter preparation includes a working defroster, suitable wipers and washer fluid protected against freezing. Do not start relying on equipment before confirming it can keep your view clear.
Source: South Carolina Commercial Driver's License Manual, posted 179-page PDF, body version March 2025; 2.13.1 Vehicle Checks / defrosters, wipers and washers (physical PDF pages 61–62); printed page 2-29–2-30, physical PDF page 62; reviewed September 21, 2026. ↗
Snow and ice cover a truck's steps and handholds. What should happen before using them?
Correct answer: Clear them so you have secure footing and a reliable grip.
Winter inspection includes clearing snow and ice from steps and handholds. Secure access reduces the risk of a fall; jumping or relying on eventual melting is not a sound substitute.
Source: South Carolina Commercial Driver's License Manual, posted 179-page PDF, body version March 2025; 2.13.1 Vehicle Checks / access and winterfront; printed page 2-30, physical PDF page 62; reviewed September 21, 2026. ↗
After a long drive on a hot day, tire pressure is above its cold reading. Should you bleed air merely to restore the cold reading?
Correct answer: No. Recheck under the proper cold-inflation conditions.
Pressure normally rises as a tire heats. Bleeding it to the cold figure while hot can leave it underinflated after cooling. Follow the specified cold-pressure check and stop to investigate overheating.
Source: South Carolina Commercial Driver's License Manual, posted 179-page PDF, body version March 2025; 2.14.1 Vehicle Checks / tires and engine coolant; printed page 2-31, physical PDF page 63; reviewed September 21, 2026. ↗
The engine overheats and the cooling system is still hot. What should you do about a pressurized radiator or coolant cap?
Correct answer: Leave it closed until the system has cooled and follow service instructions.
Hot pressurized coolant can escape and cause severe burns. Stop safely, allow the system to cool and follow the vehicle's service procedure. A hot cap should not be opened as an immediate cooling shortcut.
Source: South Carolina Commercial Driver's License Manual, posted 179-page PDF, body version March 2025; 2.14.1 Vehicle Checks / tires and engine coolant; printed page 2-31, physical PDF page 63; reviewed September 21, 2026. ↗
Why must a driver monitor engine temperature when using a winter front or radiator cover?
Correct answer: Restricting airflow too much can cause the engine to overheat.
A winter cover changes cooling airflow. Too much restriction can overheat an engine even in cold weather, so use the proper equipment and monitor temperature.
Source: South Carolina Commercial Driver's License Manual, posted 179-page PDF, body version March 2025; 2.13.1 Vehicle Checks / access and winterfront; printed page 2-30, physical PDF page 62; reviewed September 21, 2026. ↗
