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Question

Difficulty: MediumWinter Driving

When preparing a commercial motor vehicle for operation after heavy snowfall in freezing conditions, place the following cold-start and visibility preparation steps in the correct chronological order from first to last.

  1. 1Start the engine and verify that oil pressure reaches normal operating levels.
  2. 2Engage the cab heater and defroster controls to direct warm airflow toward the windshield and side windows.
  3. 3Clear all accumulated snow, ice, and frost manually from all windows, mirrors, lights, reflectors, and the trailer roof.
  4. 4Operate the windshield wipers and fluid washer system to confirm winter-grade solvent sprays properly across clean glass.

Answer

The correct chronological sequence is: (1) Start the engine and verify oil pressure, (2) Engage the cab heater and defroster controls, (3) Clear all accumulated snow and ice manually from glass, mirrors, lights, and roof, and (4) Operate the windshield wipers and fluid washer system.
The correct sequence begins with starting the engine and verifying oil pressure to safely generate engine heat. Next, engaging the defroster directs warm air to begin thawing the windshield. Then, manual removal of snow and ice from all exterior glass, mirrors, lights, and roof surfaces ensures complete visibility. Finally, testing the windshield wipers and washer fluid on clean, thawed glass confirms visibility controls function properly without damaging the wiper blades.

Step-by-Step Solution

1
Start the engine and monitor dashboard gauges until oil pressure stabilizes within the manufacturer's specified operating range.
The engine safely begins generating heat without internal lubrication damage.
Commercial vehicle defroster and heating cores require engine coolant flow, which cannot operate until the engine is started and stabilized.
2
Set the cab climate controls to activate the defroster and heater fans at the required temperature.
Heated air begins warming the windshield and front side glass to soften bonded ice.
Starting the defroster early reduces the effort needed to remove ice and prevents immediate refogging.
3
Use appropriate brushes and scrapers to remove snow, slush, and ice from all windows, mirrors, lights, reflectors, and roof surfaces.
Full 360-degree driver visibility is established and exterior illumination devices are unobstructed.
Federal safety standards and CDL guidelines require all exterior viewing surfaces and lights to be completely clear of snow and ice prior to travel.
4
Activate the windshield wiper control and washer fluid pump to verify clean blade sweeping and freeze-resistant spray coverage.
Wiper blades move smoothly across thawed glass and confirm full washer system functionality.
Operating wiper blades across frozen, encrusted windshields will tear the rubber edges or burn out the wiper motor; wiping must only occur on cleared glass.

Key Concept

Winter Pre-Trip Cab Heating and Full Visibility Preparation
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Topics

Winter Driving

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