Peterbilt 330/335/337 Cab Lights

Frequently Asked Questions About Peterbilt 330, 335, and 337 Cab Lights

Will these cab lights fit my Peterbilt 330, 335, or 337?

Peterbilt 330, 335, and 337 cab lights are designed to fit select Peterbilt medium-duty truck models, with many aftermarket cab lights fitting trucks manufactured from 2005 through 2015. Exact cab light fitment depends on your truck?s model year, roof contour, cab design, mounting hole spacing, wiring setup, and whether the cab already has factory-drilled mounting holes.

Some 2016 and newer Peterbilt 330/335/337 models may require different cab light mounting brackets or hardware because of cab design changes. Before ordering, verify your truck?s model year, VIN, OEM part number, roof layout, and existing cab light mounting points. If your truck does not have factory mounting holes, additional drilling and sealing may be required during installation.

Can I install Peterbilt 330/335/337 cab lights if my truck does not have factory mounting holes?

Peterbilt 330/335/337 cab lights can be installed on trucks without factory mounting holes, but the installation requires drilling through the cab roof. This type of cab light installation usually takes 2 to 4 hours for an experienced installer and requires careful measuring, drilling, wiring, and sealing.

Common tools and materials may include a drill with metal bits, center punch, masking tape, measuring tape, wiring connectors, butyl tape, and high-quality sealant. The installer must mark each cab light location, drill pilot holes, enlarge the holes for the light bases or wiring, mount the lights, and seal each opening properly to help prevent roof leaks. Professional installation is often recommended for trucks without pre-drilled cab light mounting holes and may cost approximately $200 to $400 depending on the shop and location.

What is the difference between LED and incandescent Peterbilt 330/335/337 cab lights?

Peterbilt 330/335/337 cab lights are commonly available in LED and incandescent styles. LED cab lights use less power, provide brighter and more consistent illumination, last longer, and resist vibration better than traditional incandescent cab lights.

LED cab lights may draw up to 90% less power and can last 50,000 or more hours, while incandescent bulbs may last around 2,000 hours and often need replacement every 1 to 2 years. Incandescent cab lights usually cost less upfront, but LED cab lights may provide better long-term value because they require less maintenance. In many cases, LED cab lights and incandescent cab lights can use the same mounting configuration, allowing a later upgrade from incandescent to LED without drilling new mounting holes.

Are Peterbilt 330/335/337 cab lights DOT compliant?

Peterbilt 330/335/337 cab lights should meet DOT and FMVSS 108 requirements when they are properly selected, installed, wired, positioned, and maintained. Cab lights used on commercial trucks must be installed in the correct location and use the correct approved light color for front-facing marker and clearance light applications.

For most commercial vehicle applications, amber is the standard required color for front-facing cab marker lights. Some configurations may use clear lenses with amber bulbs or amber LEDs, depending on the light design and applicable regulations. Always check the product listing for DOT compliance information and verify your state or fleet requirements before installing aftermarket cab lights.

What cab light colors are legal for Peterbilt 330, 335, and 337 trucks?

Amber cab lights are the standard legal choice for front-facing Peterbilt 330/335/337 cab lights used as marker or clearance lights. Amber lights help identify the truck?s width and improve visibility for other drivers.

Red, blue, and green cab lights are generally not legal for front-facing on-road commercial vehicle use because those colors may be reserved for emergency, law enforcement, or special-use vehicles. Some states may also have additional requirements for cab light color, position, spacing, brightness, and lens type. Check local regulations before installing custom-colored cab lights on a Peterbilt 330, 335, or 337.

How do I prevent water leaks after installing Peterbilt 330/335/337 cab lights?

To prevent water leaks after installing Peterbilt 330/335/337 cab lights, each light base, mounting hole, and wiring opening must be sealed correctly. Proper cab light sealing is especially important when drilling new holes through the cab roof.

Use butyl rubber tape under each cab light base before mounting, then apply a bead of high-quality silicone or exterior-grade sealant around the light perimeter. Avoid over-tightening the mounting screws because excessive pressure can crack plastic housings, distort gaskets, or weaken the seal. Inspect the cab lights and sealant at least once a year, especially before winter or heavy rain seasons.

What are signs that my Peterbilt cab lights are leaking?

Common signs of leaking Peterbilt cab lights include fogging inside the lens, water stains on the headliner, moisture around the cab light base, corrosion near the mounting screws, flickering lights, or electrical issues in the cab light circuit.

If you notice moisture inside the cab or lens after installing cab lights, remove the affected light, inspect the gasket and mounting holes, clean the surface, and reseal the light before more water reaches the cab roof, headliner, or wiring. Fixing a small leak early can help prevent rust, interior water damage, and electrical problems.