Head Lights, Bulb or wiring?

The other night I was driving at night and got behind a SUV at a traffic light and noticed one of my head lights were out… So I pulled over in a parking lot and tapped the light… It came back on and worked for the rest of the trip… I have had to tap the light to get the bulb to turn on now a few more times since… It’s not 100% of the time but probably 85-90% of the time, that I need to do this. A light tap is all it takes and once it lights it stays on for the length of the trip…

So do you guys think its a bad bulb or a loose wire?? I have never seen a bulb fail like this, and that is why I am asking.

i had the same problem and the bulb was bad or i should say it was on its way out.

Sometimes A Bulb’s Filament Can Become Detached At One End, Part Of The Burning Out Process, And It Looses Its Contact And Ability To Conduct/Resist Electricity And Goes Out. By Tapping It, The Filament Moves Just Enough To Recontact At The Detached End And It Lights, Temporarily. It Will Finally Go Out And Stay Out.

Removing and examining the bulb carefully, while it’s off, and tapping it, you should be able to see a filament jiggling on one end if it’s loose. These bulbs rely on the “glass” to be clean and one should take care not to put finger prints on them to avoid early burn-out.


GS, What Is The Make, Model, Model-Year ?

If this were my car, I’d just replace the bulb first and see what happens. Even if it’s not the bulb, you should end up with a slightly brighter light and you shouldn’t have to replace the bulb again for a while.

It would be nice to know how old the car is and what it is.
Anyway, I’ve seen bulbs do this. CSA explained the reason.
In my vahicles, when one bulb goes I assume they’re probably clos ein life expectancy and I change both sides. It’s a safety issue.

If You Were Really Thrifty Or Wanted To Bother With An Experiment, You Could Swap Bulbs, Right And Left, And See If The Intermittent Light Moves Across To The Other Side.

I’d replace the bulbs as a pair (R&L side) if you’re going to replace one, especially if they’ve been there for a while or you can’t remember replacing them.


Check the connectors. They can get get dirty and make bad contact after a while. I’ve had to replace several on our Subies. Dirty contacts have higher resistance, causing the connector to get hot and melt. For whatever reason, Subaru is prone to having that problem but clearly other cars can have similar problems.
You can clean the connector with contact cleaner bought from Radio Shack. Maybe carefully pinch them in a little with some pliers so they grab better and, before you put them back on the bulb, put some dielectric (any car parts store has it) grease on the contact to protect them from the elements.

Bad bulb is very likely. They often do this when they are “on the way out”. Pretty soon it won’t work at all.

Changed the bulb and took it as an opportunity to remove the hazing on the headlight. CSA was right after I pulled the old bulb you could see where the filiment broke.

I have never subscribe to the replace both bulbs at the same time thought process. Especially when the car was purchased used and I can almost guarantee that the DSPO did nit follow that rule eather

@Amit-8, Excellent Reply. Although 7 years late. In the future please look in the upper right corner of the comment box to see the date. In this case the original poster (OP) solved the problem in January 2013.

@cdaquila Amit-8 is posting the same Spam that was removed a few days ago.

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