2019 Kenworth T680 Bulb Sizes

Quick reference

The 2019 Kenworth T680, a popular choice for long-haul trucking, offers a variety of lighting options that can sometimes make bulb replacement a bit confusing. While many T680s come equipped with standard halogen bulbs, Kenworth also offered optional LED lighting packages, particularly for headlights and some exterior marker lights. It's crucial to verify your truck's specific configuration before purchasing replacement bulbs to ensure compatibility.

For the headlights, most 2019 T680 models feature halogen bulbs, with H11 for the low beams and H7 for the high beams. However, higher trim levels or specific option packages might have included factory LED headlights, which are not designed for bulb replacement but rather require replacement of the entire headlamp assembly if a component fails. Fog lights commonly use H10 or H16 bulbs, and again, some premium trims might have integrated LED fog lights. Daytime Running Lights (DRLs) often utilize a 7443 incandescent bulb, but LED DRLs were also available on certain configurations.

Exterior marker and signal lights, such as the front and rear turn signals, brake lights, and tail lights, typically use 3157 incandescent bulbs. Reverse lights are commonly 921 incandescent bulbs, and license plate lights usually take a 194 bulb. Side marker lights also frequently use 194 incandescent bulbs, though LED versions were an upgrade option. Interior dome and map lights most often use a 578 or 212-2 style bulb, with LED upgrades being a popular choice for improved brightness and longevity.

LED vs halogen upgrade considerations

Upgrading from halogen to LED bulbs in your 2019 Kenworth T680 can offer significant benefits, including brighter illumination, a whiter light output, and a longer lifespan. However, there are several considerations to keep in mind to ensure a smooth transition.

One of the most common issues when upgrading to LED bulbs is the potential for CANBUS errors. The T680's electrical system, like many modern vehicles, monitors the power draw of its lights. LED bulbs draw significantly less power than their halogen counterparts, which can trick the truck's computer into thinking a bulb is out. This often triggers "bulb-out" warning messages on the dash or causes hyper-flashing for turn signals. To circumvent this, "CANBUS-ready" or "error-free" LED bulbs with built-in resistors are often necessary. In some cases, external load resistors may need to be wired in parallel with the LED bulbs to simulate the power draw of a halogen bulb.

Additionally, some LED conversions, especially for headlights, may require adapter rings or special housings to ensure proper fitment and beam pattern. Halogen headlights are designed to work with a specific filament position, and an LED bulb's light-emitting diodes need to be precisely aligned to achieve a correct and safe beam pattern. Poorly aligned LED headlights can create glare for oncoming traffic or have an ineffective light distribution. Always research and choose high-quality LED conversion kits specifically designed for heavy-duty truck applications to ensure compatibility and optimal performance. For interior lights, the conversion is generally more straightforward, though ensuring the correct base type and length for dome/map lights is crucial.

How to replace each bulb

Replacing bulbs on your 2019 Kenworth T680 is generally a straightforward process, but some locations can be more accessible than others. Always ensure the truck is off and the lights are cool before attempting any bulb replacement.

• Low Beam/High Beam Headlights: Access is typically from behind the headlight assembly under the hood. You may need to remove a dust cap or cover. Twist the bulb counter-clockwise to remove, then disconnect the electrical connector. Reverse the process for installation. Be careful not to touch the glass of new halogen bulbs, as oils from your skin can create hot spots and shorten their lifespan.
• Fog Lights: These are usually accessed from underneath the front bumper or through the wheel well liner. You may need to remove a few fasteners to gain access.
• DRL, Front Turn Signal, Side Marker: Access varies but is generally from the front of the vehicle. For some, you might reach behind the assembly, while others may require popping off a lens cover.
• Rear Turn Signal, Brake Light, Tail Light, Reverse Light: These are almost always accessed by removing the lens cover of the tail light assembly. Typically, several screws hold the lens in place. Once removed, bulbs usually twist out of their sockets.
• License Plate Light: Often, you'll need to carefully pry off the clear lens cover to access the bulb. Small flathead screwdrivers are usually sufficient.
• Dome/Map Light: These interior lights usually have a plastic lens cover that can be carefully pried off with a plastic trim tool or a small flathead screwdriver. Be gentle to avoid damaging the plastic.

Common lighting issues for this generation

Owners of the 2019 Kenworth T680 might encounter a few common lighting issues specific to this generation. Beyond typical bulb failures, electrical issues can sometimes arise.

• Corrosion in Sockets: Due to exposure to the elements, exterior bulb sockets, especially for side markers, tail lights, and fog lights, can develop corrosion. This can lead to intermittent operation or complete failure of the bulb, even if the bulb itself is good. Cleaning the contacts with electrical contact cleaner and a small brush can often resolve this.
• Flickering Lights (especially after LED upgrade): As mentioned, incorrect LED installations or non-CANBUS compatible bulbs can lead to flickering or inconsistent operation due to the truck's electrical system not recognizing the low power draw.
• DRL Malfunctions: The DRL system can sometimes show intermittent issues, which might be related to the DRL module or wiring rather than just the bulb. Diagnostics may be needed to pinpoint the exact cause.
• Trailer Light Issues: While not directly truck bulbs, issues with the truck's wiring harness or trailer light modules can lead to problems with trailer lighting, often mirrored by dash warnings. Always check the truck's connectors and fuses if trailer lights are malfunctioning.

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