Kenworth W990 Bulb Size Guide: Headlights, Signals & Markers

Kenworth W990 bulb specifications: identify your installed lamps

Kenworth’s January 2026 operator manual contains a shared lighting table for the T680, T880 and W990. The table below preserves its equipment and SAE/ECE designations. It does not establish that every listed option is fitted to every W990, or a model-year range for these bulbs. Check the marking on your existing bulb and headlight assembly before ordering.

Source: Kenworth T680 / T880 / W990 Operator’s Manual, Y53-1200-1N1 (January 2026), section 25.7, pages 326–327. SAE and ECE are the source’s equipment-standard designations; they do not establish fitment by country. The manual does not state a vehicle bulb quantity or list a fog, reverse, licence-plate or roof-clearance bulb code in this table.

W990 low beam and high beam: match the complete bulb code

For a serviceable halogen headlight, Kenworth lists H11-LL (SAE) or H7 (ECE) for low beam and HB3A – LL for high beam. The manual says the long-life version is not required. Match the specification to your installed assembly; an aftermarket headlight may call for a different bulb.

The shared manual also lists a D1-S HID low-beam option and non-serviceable LED headlights. These are different equipment configurations. HID service requires a trained technician, and an integrated LED headlight does not take a replacement halogen bulb.

PACCAR headlamp guidance: Kenworth prohibits installing LED replacement light sources in PACCAR headlamps. Incorrect bulb types can overheat because of the internal optics and may cause a fire. Follow the instructions for your exact headlamp; matching a bulb designation does not override this restriction. See section 16.2, pages 301–302.

H11 low-beam LED bulbs for compatible serviceable lamps

Compare the H11 low-beam product below with the installed lamp’s specification, connector and available space. Low-beam installation requirements are separate from the tested 9005 high-beam fit below.

LED headlight conversion bulbs may not comply with FMVSS/CMVSS requirements for on-road use. Check applicable state and provincial laws before use.

Shop Kenworth W990 9005 LED high beams

BTS-tested high-beam fit: the original Kenworth W990 halogen specification is HB3A-LL; shop 9005 LED high-beam replacements. BTS has confirmed that its current Alpha, Morimoto and GTR 9005 offerings fit the original high-beam housings without clearance issues. The original code is retained for reference; it does not require a separate LED shopping size.

Choose from Alpha, Morimoto 2Stroke 4.0 and GTR Ultra 3.0 below. The Morimoto and GTR listings each contain two bulbs. These high-beam products are separate from the signal bulbs.

W990 turn signals, daytime running lights and markers

The shared manual lists 4157K (SAE) or 3157K (ECE) in one combined row for daytime running lamps, position lamps, turn signals and halogen side markers. Those are the original incandescent specifications. For LED replacements, shop the 3157/4157 family, then match the required light colour and the product’s socket-wiring and DRL compatibility. BTS confirms two bulbs for the T880/W990 signal group: one pair.

Kenworth’s T880/W990 headlight drawing identifies the daytime running light and turn signal together, with separate low and high beams. Confirm the actual lamp, circuit and intended function before selecting an LED signal replacement. LED side markers and rear tail/turn lamps are listed separately as LED equipment in the shared table.

Choose signal bulbs by your DRL setting

BTS-tested quantity: two 3157/4157 signal bulbs — one pair. The T880 and W990 use one pair for this signal/parking group. This is separate from the headlight bulbs.

• Low-beam DRL, or signal DRL disabled: BTS recommends Alpha amber bulbs for brightness and reliability.
• High-power signal circuit used as the DRL: BTS recommends Morimoto XB amber bulbs. In BTS testing, their output visibly reduces after the circuit stays energized, protecting the bulbs during sustained use.

Alpha signal bulbs do not step down in sustained high-power mode and can eventually fail in that DRL application. Kenworth dealers can change the T880/W990 DRL programming between the signal-light and low-beam settings. Choose by the truck’s actual programming.

Product note: Morimoto XB supports standard and CK sockets. Its separate exclusion for PWM-driven DRL circuits still applies; contact BTS if that is your setup.

Alpha Series W990 complete LED headlight assemblies

The Alpha Series W990 LED headlight is a complete assembly with a manufacturer-listed 2018–2025 W990 application. BTS sells the driver and passenger sides separately: choose the required side and match the original housing and Kenworth multi-pin connection. This left-hand-drive assembly is separate from the replacement bulbs above.

The assembly’s optional DRL harness is also separate from the original signal-bulb DRL programming described above. Use the product’s installation guide and confirm the contents supplied with an individual-side order.