2014 Kenworth W900 Bulb Sizes

Quick reference

The 2014 Kenworth W900, a true icon of the road, offers a range of lighting options that can vary based on trim and factory specifications. While many W900s came equipped with traditional halogen lighting, some may feature projector-style headlights with High-Intensity Discharge (HID) bulbs for enhanced visibility. LED options for tail, brake, and turn signals were also available as factory upgrades or often installed as aftermarket enhancements.

LED vs halogen upgrade considerations

Upgrading from halogen to LED bulbs in your 2014 Kenworth W900 can offer significant advantages, including brighter light output, longer lifespan, and reduced power consumption. However, there are several key considerations to keep in mind:

• CANBUS Errors: Modern vehicles, including the Kenworth W900, use a CANBUS (Controller Area Network Bus) system to monitor various electrical components, including lighting. LED bulbs draw significantly less power than halogen bulbs, which can sometimes trigger "bulb out" warnings or hyper-flashing (rapid blinking) in the turn signals. To prevent these CANBUS errors, you'll often need to install load resistors or CANBUS-compatible LED bulbs. These resistors mimic the electrical load of a halogen bulb, tricking the vehicle's computer into thinking everything is operating normally.
• Adapters Needed: Depending on the specific bulb type and your chosen LED kit, you might need adapter harnesses to ensure a proper fit and connection. Some LED bulbs for headlights, for instance, come with larger heat sinks that may require more space or specific mounting adapters.
• Beam Pattern: When upgrading headlights to LED, especially in reflector housings (not projector-style), it's crucial to choose LEDs designed to mimic the halogen filament's light output. Poorly designed LEDs can scatter light, creating glare for oncoming traffic and reducing your effective visibility. Projector headlights are generally more forgiving with LED upgrades.
• Heat Dissipation: LEDs generate heat, but in a different way than halogens. Good quality LED bulbs will have active cooling (fans) or substantial passive heat sinks. Ensure there is adequate space around the bulb for proper heat dissipation to maximize their lifespan.

How to replace each bulb

Replacing bulbs on your 2014 Kenworth W900 is generally straightforward, though access can sometimes be tight. Always ensure the truck is turned off and the parking brake is engaged before attempting any bulb replacement.

• Low Beam/High Beam: Access is typically from behind the headlight assembly. You may need to remove a dust cover or trim panel. Twist to remove the old bulb, disconnect the electrical connector, and connect the new bulb. Be careful not to touch the glass of new halogen bulbs, as oils from your skin can cause hot spots and premature failure.
• Fog Light: Often accessed from underneath the bumper or by removing a fender liner. Twist or unclip the bulb from its housing.
• DRL/Front Turn Signal: These are usually combined in a single bulb (3157/7443) and accessed similar to the low beam or by reaching behind the front grille/light assembly.
• Rear Turn Signal/Brake Light/Tail Light: On many W900s, these are modular LED units or traditional incandescent bulbs accessed by removing the lens cover from the rear light assembly. For incandescent, twist the bulb socket out and pull the old bulb straight out.
• Reverse Light: Similar to the rear turn signals, accessed by removing the lens cover or a specific access panel.
• License Plate: Typically involves unscrewing a small lens cover above the license plate to access the bulb.
• Side Marker: These small lights often have a lens that pops off, or the entire assembly twists out from the fender or side of the cab.
• Dome/Map Light: These interior lights usually have plastic lens covers that can be carefully pried off with a small flat-head screwdriver to reveal the festoon-style bulb.

Common lighting issues for this generation

Owners of the 2014 Kenworth W900 may encounter a few common lighting issues:

• Corroded Sockets: Especially in older trucks exposed to harsh weather, bulb sockets can corrode, leading to intermittent connection or complete bulb failure. Cleaning the contacts with electrical cleaner or replacing the socket can resolve this.
• Trailer Wiring Issues: Given the W900's primary role, trailer wiring faults are common. A bad ground on the trailer or a short in the trailer's lighting system can cause issues with the truck's tail lights, brake lights, or turn signals.
• DRL/Turn Signal Hyper-Flashing: As mentioned, if an incandescent DRL/turn signal bulb burns out, or if an incompatible LED is installed without a load resistor, the turn signals may flash rapidly (hyper-flash).
• Headlight Haze/Yellowing: Over time, the clear plastic headlight lenses can become cloudy or yellowed due to UV exposure. This significantly reduces light output and can be restored with a headlight restoration kit or by replacing the assemblies.
• Intermittent Headlight Operation: This can be caused by a loose connection, a failing ballast (for HID systems), or a fatigued wiring harness. Investigation usually starts at the source of power and moves towards the bulb.

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