'79 300SD Right Front Headlight Failure

[svm]

I bought this car a few months ago, and I am pretty new to all this. This is my first real problem with it. Seems minor enough, but it's a little strange...

When I use the headlights normally, only the left one comes on. With highbeams, all four work - including the right headlamp. If I use the fog lights, the left one comes on along with the fog lights, but no right one. I assume that if it was just the bulb, it wouldn't come on with the highbeams.

I checked the fuses.

Is it the switch? Is there any way to troubleshoot it before I start removing panels to get to the switch and risk going down the rabbit hole?

Any advise (so long as it's good) is welcome.

Thanks.

[1980sd]

Check your grounds. There is a wad of brown wires on the drivers side near the radiator. Look from the engine compartment.

Good luck! Probably something simple.

[svm]

Thanks! Will do...

[KJenkins]

I recently had the same problem with my 1980 300sd. The problem is probably the light itself. On the 116 chassis the outer oval light has a two filament bulb, both low and high beam. The low beam on your bulb has probably burnt out. The light is usually a sylvania sealed beam and costs about 8 dollars.

[svm]

It was in fact just the bulb/reflector. Ordered it online for about $9, and it took about 10 minutes to swap out.

Thanks for your advise.