A truck with hydraulic brakes loses pedal pressure. Which temporary response does the handbook describe as sometimes rebuilding enough pressure to help stop?
Correct answer: Pumping the hydraulic brake pedal.
For hydraulic pressure loss, pumping the pedal may build temporary pressure. This is not an instruction for air brakes or normal ABS operation. Stop safely and have the fault corrected; a temporarily firmer pedal does not make the truck serviceable.
Source: Wisconsin Commercial Driver's Manual, May 2026; Section 2; 2.17.3 Loss of Hydraulic Pressure; printed and physical PDF page 86; reviewed September 20, 2026. ↗
A front tire blows out, but no immediate collision requires emergency braking. What should you do first?
Correct answer: Hold the wheel firmly and let the truck slow without hard braking.
A blowout can pull or destabilize the truck. Keep a firm grip, avoid braking initially unless needed to avoid an immediate collision, and slow before braking gently and stopping safely.
Source: Wisconsin Commercial Driver's Manual, May 2026; Section 2; 2.17.4 Tire Failure / Respond to Tire Failure; printed and physical PDF page 87; reviewed September 20, 2026. ↗
You hear a tire burst but the truck still seems to handle normally. What should happen after you reach a safe stopping place?
Correct answer: Inspect all tires because one tire in a dual pair may have failed.
A dual tire can fail without dramatic handling changes. Do not assume normal steering proves the tires are sound; stop safely and check all tires.
Source: Wisconsin Commercial Driver's Manual, May 2026; Section 2; 2.17.4 Tire Failure; printed and physical PDF page 87; reviewed September 20, 2026. ↗
What is the main benefit of functioning ABS during hard braking?
Correct answer: It reduces wheel lock so the driver can retain more steering control.
ABS helps prevent wheels from locking during braking and can help preserve control. It does not create traction, guarantee a shorter stop or justify higher speeds and smaller gaps.
Source: Wisconsin Commercial Driver's Manual, May 2026; Section 2; 2.18.4 How ABS Helps You; printed and physical PDF page 88; reviewed September 20, 2026. ↗
An ABS warning lamp remains on after its normal self-check or comes on while driving. What does that suggest?
Correct answer: An ABS fault may exist; normal brakes may still work, but service is needed.
A warning beyond normal startup behavior can indicate an ABS problem. With otherwise sound brakes, conventional braking remains, but ABS assistance may be lost. Have the problem serviced and do not confuse the normal initial lamp check with a fault.
Source: Wisconsin Commercial Driver's Manual, May 2026; Section 2; 2.18.7 Braking if ABS Is Not Working; printed and physical PDF page 89; reviewed September 20, 2026. ↗
A tractor has functioning ABS but its trailer does not. Is the tractor's ABS still useful?
Correct answer: Yes. It can help retain tractor control even without trailer ABS.
ABS can still offer benefits on the part of the combination that has it. Tractor ABS does not make an unequipped trailer an ABS trailer, so avoid assuming identical anti-lock protection throughout the combination.
Source: Wisconsin Commercial Driver's Manual, May 2026; Section 2; 2.18.5 ABS on the Tractor Only or Only on the Trailer; printed and physical PDF page 88; reviewed September 20, 2026. ↗
In a straight-line emergency stop with properly functioning ABS on all axles, how should the driver generally use the service brake?
Correct answer: Apply firm, steady pressure without pumping the pedal.
With functioning ABS, use the braking needed while letting the system manage wheel lock. Pumping or routine stab braking interrupts the intended operation; ABS still does not remove traction and stopping-distance limits.
Source: Wisconsin Commercial Driver's Manual, May 2026; Section 2; 2.18.6 Braking with ABS; printed and physical PDF page 89; reviewed September 20, 2026. ↗
A truck's front tires have lost grip and it continues straight despite steering input. Will turning the wheel much farther solve the skid?
Correct answer: No. Reduce the excessive speed or braking input so traction can return.
In a front-wheel skid, the tires cannot provide the requested steering force. More steering alone does not restore grip. Ease the excessive input causing the skid and slow as safely as possible.
Source: Wisconsin Commercial Driver's Manual, May 2026; Section 2; 2.19.3 Front-Wheel Skids; printed and physical PDF page 91; reviewed September 20, 2026. ↗
Why can locked tractor drive wheels during braking develop into a jackknife?
Correct answer: The trailer can push the tractor's sliding rear end sideways.
Locked drive wheels have little directional control. The trailer can push the tractor's rear out of line, folding the combination. Prevent wheel lock and use braking appropriate to the vehicle and conditions.
Source: Wisconsin Commercial Driver's Manual, May 2026; Section 2; 2.19.1 Drive-Wheel Skids; printed and physical PDF page 90; reviewed September 20, 2026. ↗
You stop to help at a crash and can choose a safe place to park. Why should you stay clear of the immediate crash area?
Correct answer: Emergency vehicles need access and another collision must be avoided.
Protect the area from further collisions without blocking responders. Park safely away from the immediate scene, warn traffic as appropriate and provide the location when calling for help.
Source: Wisconsin Commercial Driver's Manual, May 2026; Section 2; 2.20.1 Protect the Area; printed and physical PDF page 91; reviewed September 20, 2026. ↗
Smoke indicates a truck fire and the vehicle can still be stopped safely. Which location is preferable?
Correct answer: An open area away from buildings, brush and other vehicles.
Stop off the road in a suitable open area when possible, away from things that can catch fire, and notify emergency services. A fuel station is an especially unsuitable place to take a burning vehicle.
Source: Wisconsin Commercial Driver's Manual, May 2026; Section 2; 2.21.3 Fire Fighting / Pull Off the Road; printed and physical PDF page 92; reviewed September 20, 2026. ↗
After stopping safely for an engine fire, what should you avoid?
Correct answer: Opening the hood and feeding the fire with more air.
Stop the engine as soon as you can safely do so. Avoid opening the hood, which can supply oxygen and intensify a fire. Prioritize getting clear and contacting emergency services over attempting risky access.
Source: Wisconsin Commercial Driver's Manual, May 2026; Section 2; 2.21.3 Keep the Fire from Spreading; printed and physical PDF page 92; reviewed September 20, 2026. ↗
Smoke is coming from inside a closed box trailer. Why should the driver keep the cargo doors shut?
Correct answer: Opening them can add oxygen and make the fire flare up.
Opening a burning cargo compartment can rapidly feed the fire. Keep the doors closed, stay clear and call emergency services, especially when the cargo may include hazardous materials.
Source: Wisconsin Commercial Driver's Manual, May 2026; Section 2; 2.21.3 Keep the Fire from Spreading; printed and physical PDF page 93; reviewed September 20, 2026. ↗
You do not know what is burning in a load that may contain hazardous materials or which extinguisher is suitable. What should you do?
Correct answer: Keep clear and let trained firefighters handle the fire.
The wrong extinguishing method can worsen a fire or create another hazard. If the material or suitable agent is uncertain, keep clear, notify responders and leave the response to trained firefighters.
Source: Wisconsin Commercial Driver's Manual, May 2026; Section 2; 2.21.3 Use the Right Fire Extinguisher; printed and physical PDF page 93; reviewed September 20, 2026. ↗
A trained person has judged a small fire safe to tackle with a suitable extinguisher and a clear escape route. Where should the discharge be aimed?
Correct answer: At the base or source of the fire.
An extinguisher must act on the source of the fire rather than just its upper flames. This does not mean approaching a large, unknown or unsafe fire; leave when conditions are unsafe and call emergency services.
Source: Wisconsin Commercial Driver's Manual, May 2026; Section 2; 2.21.3 Extinguish the Fire; printed and physical PDF page 93; reviewed September 20, 2026. ↗
Visible flames and smoke have stopped after a vehicle fire. What should a driver remember?
Correct answer: Hot material can reignite; the absence of flames is not an all-clear.
Material may remain hot and reignite even when flames or smoke are no longer visible. Do not treat that appearance as permission to resume driving; keep clear and follow the emergency response and inspection process.
Source: Wisconsin Commercial Driver's Manual, May 2026; Section 2; 2.21.3 Extinguish the Fire; printed and physical PDF page 93; reviewed September 20, 2026. ↗
