How to diagnose and resolve a one headlight dimmer than the various other issue

If you have a instance through one headlight dimmer than the various other, the trouble can be led to by numerous various components, from a cloudy headlight lens or old headlight bulb, to a wiring difficulty. Here’s a straightforward list of items to inspect to uncover the resource of the problem.

You are watching: Why is one headlight dim and the other bright

Cloudy headlight lenses?

Compare the lens problem of each headlight.


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Rerelocate oxidized coating, polish, and re-use brand-new UV protective coating


When the headlight clear coat deteriorates, the plastic lens oxidizes and turns cloudy. A cloudy lens deserve to alleviate light output by up to 70%. If your headlight lens is cloudy, you have the right to reproblem it yourself via a headlight restoration kit. See this article for instructions.

Is the headlight bulb worn?

As headlight bulbs accumulate burn hrs, the filament vaporizes and also leaves a grey or brvery own metallic deposit on the inside of the headlight capsule. The deposit acts like a light filter and can drastically mitigate the light output from that bulb, causing the one headlight dimmer than the various other worry.

Remove the headlight bulbs and compare them for deposits. If the dim headlight has proof of these deposits, rearea it and then view if one headlight is dimmer than the various other. If so, proceed to the following action.

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Check and also clean the headlight ground connection

Many kind of motorists think that a dim headlight is led to by a negative power link. That’s hardly ever the instance. It’s much more likely that car is delivering enough power, yet the ground connection is corroded, therby reducing light output.

Depfinishing on the year, make or design, the headlights may have actually a prevalent ground for both the left and right headlights, or each headlight may have actually its own ground. See the wiring diagrams below.

You deserve to test the ground relationships for voltage

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drop due to corrosion. But that takes much longer than sindicate cleaning the ground connection. To clean the link, sindicate remove the bolt, sand off the corrosion, coat both the ring terminal and also the body sheet metal with a light film of dielectric grease and also reassemble. Then test the headlights for uniform brightness. If the one headlight is dimmer problem disappears, you’ve resolve the difficulty.

Finally, examine the headlight connector

Some cardevices have actually reduced the wire gauge to the headlight connector and also that has led to the plastic connector to melt. The result is bad conductivity. If you have a melted connector, buy a brand-new headlight pigtail at any kind of auto parts store and also splice it in location of the melted unit.

See more: What Does It Mean If A Guy Says Why Do I Put Up With You Put Up With Him?


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Melted low beam headlight connectors


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