Replacement Light Bulbs

Match the number first

Every bulb type has a standard designation that defines its base, voltage and filament layout. Headlight bulbs use codes like HB4 (9006) or H16, while small lamps use numbers such as 57, 912 or 1034. A bulb with a different number may fit physically but behave incorrectly, so verify the number printed on the existing bulb or in the owner's manual before choosing. Remember that one vehicle uses many different bulbs: low beam, high beam, fog, license plate, dome, marker and brake or turn lights.

Bulb families you will see

• Standard halogen: the common replacement for original equipment. Predictable output and widely available sizes.
• Xenon-style halogen: halogen bulbs with a gas fill and coating that change color or output. They still operate on the halogen circuit.
• Miniature incandescent lamps: wedge and bayonet bases like T2.25 (6428), 912 or 1034 for signals, markers and interior lights. The listing gives the wattage, such as 3 W or 23/8 W for dual-function lamps.
• LED kits: conversions that replace halogen bulbs, sometimes with external drivers or heat sinks that need space behind the housing.

Reading the specs

Voltage on most vehicles is 12 V. Wattage tells you how much electrical load the bulb draws, so stay within the socket and wiring rating. A dual-filament bulb has two filaments (for example, a brake and a tail function) and the base pins are arranged so that it can only seat one way. Color temperature, listed in kelvin, describes how white or yellow the light appears, while lumens describe brightness. DOT or SAE compliance is important for road use, and rules for headlight and signal color vary by state.

Fitment and installation notes

Confirm the bulb number for your exact year, make, model and lamp position. Let the lamp cool, avoid touching halogen glass with bare hands, and seat the bulb firmly. Weather seals should be re-seated to keep moisture out of the housing. When converting to LED, verify that the new bulb fits behind the dust cover and test the beam pattern against a wall at night before relying on it on the road.

If bulbs fail repeatedly, check the socket for corrosion and burned contacts, and have the charging system and wiring tested.

Choosing wisely and avoiding mistakes

Because so many bulbs look alike, common errors come from assuming. Two bulbs with the same base can have different wattages, and a 3 W marker lamp is not interchangeable with a high-output signal lamp, since higher wattage runs hotter and can melt a lens or socket. Match both the number and the position.

• Check polarity with LEDs. Unlike incandescent lamps, many LED bulbs only work with the correct polarity. If one does not light, reversing it can help.
• Watch turn signal flash rate. LED signal bulbs draw less current and can cause fast flashing unless a load resistor or LED-compatible flasher is used.
• Replace the socket if it is corroded. A new bulb in a pitted socket may flicker or fail again.
• Keep a basic kit. Carry spares for the lamps that are hard to replace on the trail, and a small pair of pliers or a bulb puller.
• Test before reassembly. Turn the lights on with the lens off to confirm operation.