I have a 10 year old SLK in the UK. This morning I noticed a headlight was out - when i took out the bulbs only the sidelight (top bulb) was black - when swapped the bottom bulb into this holder, the bulb worked, but when i put a new bulb in the bottom space, it still doesn't work.

does this mean i need a new light cluster? because i had exactly the same problem at the rear with brake lights and ended up having a whole new fitting.

I wondered if this could be a fuse?

 

i guess your car is an auto.

For info the rear brake light problem has nothing to do with the current problem you are experiencing. The brake light problem is a DESIGN issue that MB UK REFUSE to acknowledge whilst a RECALL exists in the USA and other territories!!

You cannot tell whether a bulb has blown by its colour. Black bulbs can still work OK even if output is somewhat reduced. However a broken filament can be difficult to spot without an electrical continuity test. Very simple if you have a small DIY multimeter.

The headlamps are fused.
Fuses are located on the RH end of the dash (I think).
End cover comes off.

Try the bulb from the other side of the vehicle if you don't have a meter. The side light bulb is totally different to the headlamp bulb so not sure how you got it to fit!

Stuart