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Windshield Inspection for CDL Drivers: Cracks, Stickers, Wipers, and Defrosters
A small crack, poorly placed device, worn wiper, or weak defroster can turn ordinary weather into a visibility hazard. Learn the federal windshield area, damage exceptions, mounting limits, and a practical pre-trip routine.
Visibility is a pre-trip safety decision
The windshield is not merely a piece of bodywork that can be evaluated later. Under 49 CFR 392.7, a commercial motor vehicle may not be driven unless the driver is satisfied that required equipment—including windshield wipers—is in good working order. Section 396.13 also requires the driver to be satisfied that the vehicle is in safe operating condition before driving. Inspect from both outside and the driving position, because a defect that looks minor from the ground may sit directly in a sight line once the seat and mirrors are adjusted.
Know the federally protected windshield area
Section 393.60 generally requires the windshield to be free of discoloration or damage in a defined area. It extends upward from the height of the top of the steering wheel, excludes a two-inch border at the top, and extends between one-inch borders at each side of the windshield or each windshield panel. This geometry matters more than a casual description such as 'not directly in front of me.' Set the seat and steering position correctly, then identify whether the condition falls inside the regulated viewing area.
A single nonintersecting crack is a listed exception
The federal condition rule lists an exception for a crack that is not intersected by another crack. That does not mean every single crack is safe, acceptable under state law, or suitable for continued service. Its location, length, movement, edge involvement, effect on optical clarity, and interaction with the windshield structure can still require repair or replacement under the carrier's maintenance program. If a crack reaches another crack, forms a network, changes during the trip, or makes the road image appear distorted, stop treating it as a routine cosmetic issue.
Small damaged areas have precise spacing limits
Another federal exception covers a damaged area that can be covered by a disc three-quarters of an inch in diameter, provided it is not closer than three inches to another similarly damaged area. Measure rather than estimate. A cluster of small chips can fail the spacing condition even when each chip is individually small. Dirt, moisture, glare, and repair resin can also make the real boundary difficult to see, so clean the glass and use qualified inspection when the size or separation is uncertain.
Federal exceptions are not a promise that driving is safe
Section 393.60 sets federal equipment criteria, but the driver's safe-operation duty remains. State inspection standards, vehicle-specific requirements, carrier policies, and the actual weather or route can be more restrictive. A crack that meets a listed federal exception may still produce glare at sunrise, scatter headlights at night, distort a traffic signal, or worsen when the cab flexes. The correct question is not only whether a defect fits an exception; it is whether the vehicle can be operated with a clear, stable field of view under the expected conditions.
Check the glass, markings, seal, and mounting
For vehicles manufactured on or after December 25, 1968, glazing in windshields, windows, and doors must at least meet the applicable FMVSS No. 205 requirements and carry the required marking. Each bus, truck, and truck tractor must have a windshield, and each windshield—or each section of a multi-piece windshield—must be mounted around the full periphery of the glazing. Report a loose panel, displaced gasket, separation from the frame, water path near wiring, missing required marking, or movement when the cab flexes. Do not push a loose windshield back into position and continue.
Tint has a 70-percent federal transmittance rule in key windows
Section 393.60 allows coloring or tinting in the windshield and the windows immediately to the driver's right and left when parallel luminous transmittance through the relevant marked glazing is at least 70 percent. Film appearance alone does not prove compliance. A clear-looking aftermarket layer, residue, shade band, or combination of factory glass and added film can change total light transmission and optical quality. Drivers should not install or remove tint themselves; have uncertain glazing measured and documented by qualified personnel, and check any additional state restrictions.
Do not let ordinary devices occupy the driver's sight lines
Antennas and similar interior-mounted devices may not be more than six inches below the upper windshield edge. They must also remain outside the area swept by the wipers and outside the driver's sight lines to the road, signs, and signals. A phone cradle, toll device, camera, GPS, clipboard, decorative item, or temporary permit can create the same practical visibility problem even when its exact regulatory category differs. Evaluate the full device, bracket, cable, and anything hanging from it—not only the small attachment point.
Vehicle safety technology has its own mounting envelope
Federal rules give defined mounting positions for qualifying vehicle safety technologies on the inside of the windshield. Such a device may be no more than 8.5 inches below the upper edge of the wiper-swept area or no more than seven inches above its lower edge, and it must remain outside the driver's sight lines to the road, signs, and signals. The exception is tied to technology meeting the regulatory definition; calling an ordinary screen a safety device does not make it one. Follow approved installation instructions and carrier authorization rather than moving equipment casually between trucks.
Required decals still belong at the bottom or sides
CVSA inspection decals and stickers or decals required by federal or state law may be placed at the bottom or sides of the windshield only within the federal conditions. They may not extend more than 4.5 inches from the bottom, and they must remain outside the wiper-swept area and the driver's sight lines to the road and traffic-control information. Old permits, duplicated stickers, route notes, receipts, fuel tags, and decorative decals can accumulate gradually. Remove obsolete material through the approved process instead of allowing the viewing area to become a storage board.
Test the wiping and washing systems before weather requires them
For buses, trucks, and truck tractors manufactured on or after December 25, 1968, Section 393.78 requires compliant windshield wiping and washing systems. Earlier covered vehicles have age-specific wiper requirements. During the pre-trip, operate every speed and intermittent setting provided, check that blades travel normally and park correctly, and activate the washer. Confirm that fluid reaches the intended area without a detached hose, blocked nozzle, empty reservoir, or pattern that misses the driver's viewing zone. The narrow driveaway-towaway provision is not a general exception for an ordinary dispatch.
Blade condition matters as much as motor movement
A moving wiper can still be ineffective. Inspect blades for split or hardened rubber, missing sections, bent frames, uneven pressure, chatter, streaking, and contact with the windshield edge or mounted equipment. Clean contamination safely and use washer fluid suited to the expected temperature. Never hold or adjust a blade while the system is energized. If the motor runs but the wiped area remains smeared or incomplete, the system has not passed a functional visibility check simply because the arms move.
Defrosting and defogging must protect the driver's view
Section 393.79 requires a bus, truck, or truck tractor manufactured on or after December 25, 1968, to have a windshield defrosting and defogging system meeting the applicable FMVSS No. 103 requirements. Older covered vehicles must have a means to prevent ice, snow, frost, or condensation from obstructing the driver's view while driving. Test airflow, temperature response, outlet direction, fan operation, and mode controls before departure. A towel on the dashboard or an open side window is not a dependable substitute for a required working system.
Clear the entire necessary field before moving
Remove snow, ice, frost, condensation, dirt, salt film, insects, and interior haze from the windshield and relevant side windows before the vehicle moves. Clear mirrors, lamps, and required cameras or sensors at the same time. Do not create a small viewing hole and assume the rest will clear on the road. Idling rules and site restrictions may limit warm-up practices, so use lawful carrier procedures and allow enough time for the equipment to create and maintain a full working view.
React early when visibility deteriorates on the road
Rain, freezing spray, road salt, mud, washer-fluid failure, fogging, a spreading crack, loose glass, or a failed wiper can change a compliant departure into an unsafe trip. Reduce speed smoothly, increase space, avoid abrupt maneuvers, and stop at the first safe location if the required view cannot be maintained. Hazard flashers do not make continued blind operation acceptable. Notify the carrier with the exact condition and location, protect the stopped vehicle as required, and obtain repair or safe recovery rather than pressing on to meet an appointment.
Use one repeatable windshield callout
From outside, check glazing condition, cracks and chips, tint, required markings, seal, and full-periphery mounting. From the seat, confirm the protected viewing area is clear, devices and required decals stay within allowed locations, and sight lines to the road, signs, and signals are unobstructed. Then test all wiper settings, washer coverage, blade performance, and defrost/defog output. Review the last required vehicle report and confirm needed repairs. This guide reflects Title 49 eCFR text displayed as current through October 5, 2026; verify current federal and state rules and the carrier's procedure for the actual vehicle.
Educational summaries help you prepare, but official FMCSA and state licensing sources remain the authority for current requirements.
Official sources
49 CFR 393.60 — Glazing, windshield condition, tint, devices, and decals ↗49 CFR 393.78 — Windshield wiping and washing systems ↗49 CFR 393.79 — Windshield defrosting and defogging systems ↗49 CFR 392.7 — Equipment, inspection, and use ↗49 CFR 396.13 — Driver inspection before operation ↗ELDT.live independently creates and reviews its content. We do not present practice questions as official examination questions and do not guarantee a licensing result.