Symptoms
- Headlight doesn't turn on at all
- Headlight is noticeably dimmer than it used to be
- Both high and low beam are out, or just one of them
Likely causes
- CommonBurned-out bulbMotorcycle headlight bulbs see constant vibration and often burn out faster than a car's.
- CommonBlown headlight fuseA fuse dedicated to the headlight circuit can blow from a short or a bulb failure.
- PossibleCorroded or loose bulb connectorVibration and moisture can loosen or corrode the plug behind the headlight.
- PossibleWeak charging system causing dim lights overallIf other lights are also dim, especially at idle, suspect the stator or regulator-rectifier instead of just the bulb.
What to do
- Check if both high and low beam are affected, or just one, which helps narrow down a bulb vs. a broader electrical issue.
- Check the headlight fuse in the fuse box and replace it if blown, using the correct amperage.
- If the fuse is fine, access the back of the headlight and check the bulb connector for corrosion or looseness.
- Test or simply swap in a new bulb of the correct type and wattage if the old one looks blackened or the filament is visibly broken.
- If other lights (taillight, dash) also seem dim, especially more so at idle, check the charging system voltage rather than assuming it's just the headlight bulb.
- After replacing a bulb, avoid touching the glass with bare fingers, since oils can cause it to fail prematurely; use a cloth or gloves.
Tools and parts
- Screwdriver
- Multimeter (optional)
Headlight bulb, correct type and wattage for your bikeSearch: “headlight bulb for [your bike year make model]”
When to call a pro
If a new bulb doesn't fix it, or other electrical symptoms are present, have the charging system and wiring checked by a motorcycle mechanic.
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.