Intermittent Headlight Issue

My driver side headlight has been acting up lately. Every time I turn the truck on, the driver side headlight won't work. If I move the headlight plug around a little or just unplug it and plug it back in, the headlight will come on and stay on until I turn the truck off. If I'm away from the truck, say overnight, or all day at work, when I come back to it, headlight won't work again, and I'll have to play with the connection to get it to work.

I cleaned up the plug and put new dielectric grease on it and checked with a circuit tester and cant find an issue, but still have the same problem. My first thought was that it was the female plug connector that was the problem. If it was the problem though, I'd expect the headlights to go out while I was driving from all the vibrations, but that doesn't seem to happen.

Could it be a relay that's on the way out? Do they work intermittently before they stop working completely? Any other ideas on what the problem could be?

 

Could be the lamp. Try switching the lamps (L to R, R to L). See what happens.

 

I'll do that and see if the problem moves with the headlight.

 

Did the plug look like it had gotten hot at all? Discolored or even melted?

 

I ended up finding the problem, it turned out it was the bulb. The filament had a small break in it and I guess moving the connection around a little was enough for it to make contact and light up. I took the bulb out and took a really close look at it and saw it. It didn't look burned out. I changed the bulbs, and so far, so good.