How to Repair a Dim Headlight

Simply clean the ground connection or replace the bulb to quickly solve the problem

Simply clean the ground connection to restore the brightness of dim headlights. And apply a little dielectric grease. Or replace the bulb if you see a gray/brown film on the inside of the glass.

By the DIY experts of The Family Handyman Magazine

Repair a dim headlight

If your car has a headlight that puts out about as much light as a flashlight with weak batteries, we’ve got two simple fixes for you.

Most DIYers think they’ve got a bad headlight switch or a bad connection in the power feed. But most dim headlights are caused by a corroded ground wire. Just trace the wiring harness from the back of each headlight assembly and see where it connects to the vehicle body. Clean it as described in the photo.

Another possibility is that as headlight filaments age, they deposit a gray/brown film on the inside of the bulb (See Photo). Over time, that coating can reduce visibility by almost 300 ft. If your headlights aren’t as bright as they used to be, yank one of the bulbs and look for gray or brown residue on the glass. If you find any, replace both bulbs now and get back to seeing more of the road.

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Required Tools for this Project

Have the necessary tools for this DIY project lined up before you start—you’ll save time and frustration.

  • Adjustable wrench
  • Wire brush

Required Materials for this Project

Avoid last-minute shopping trips by having all your materials ready ahead of time. Here's a list.

  • Dielectric grease