Upgrading to LED Headlight Bulbs

Video: How to install the LED headlight H4 correctly? (YouTube)

Swapping halogen bulbs for LEDs is the quickest lighting upgrade there is: two or three times the light, crisp white colour, and usually plug-and-play. The keys are buying the right size and aiming the result properly.

1. Find your bulb size

Headlights use standardised bases — H11, H4, 9005/HB3, 9006/HB4, H7 and so on, with low beam and high beam often different sizes. Check your owner’s manual, the printing on your current bulb, or a bulb-finder chart for your exact year/model before ordering. Vehicle-specific kits (like our Sonic or Silverado sets) take the guesswork out.

2. Install

1. Work with the engine off. Access the back of the headlight (some cars hide it behind a dust cap or the wheel-arch liner).
2. Twist the old bulb counter-clockwise and unplug it. Don’t touch the glass of any halogen you plan to keep as a spare.
3. Seat the LED so its diodes face side-to-side (3 and 9 o’clock), mimicking a halogen filament — this is what keeps the beam pattern correct.
4. Plug in, refit the dust cap (larger LED bodies may need the supplied extended cap), and test low/high beam.

3. Aim the beam — don’t skip this

Park facing a wall about 25 ft away, mark the height of the headlight centres, and adjust each light’s screw so the beam cutoff sits slightly below the mark and kicks up to the right. Properly aimed LEDs light the road, not oncoming windshields — misaimed ones are what give LED upgrades a bad name.

Flicker and warnings (CANbus)

Some vehicles pulse-check their bulbs and will flicker an LED or throw a “bulb out” warning. If that happens, CANbus decoder plugs (sometimes included in kits) sit between the harness and bulb and solve it.

Legality note

LED bulbs in housings designed for halogens are generally sold for off-road/show use in the U.S.; regulations vary by state. Aim them correctly and use a white colour temperature (~6000K or lower) to stay road-courteous.

Tips

• Replace bulbs in pairs — mismatched colour looks worse than the old halogens.
• Fan-cooled LEDs need airflow; don’t wrap the body in the dust boot.