I have a 2003 S55 AMG. I have just tried unsuccessfully to replace a xenon low beam bulb. In the process I broke the carbon rod that runs outside the glass bulb. Can someone please provide me with fairly detailed instructions (and/or pictures) on how to reinsert the bulb, apply the locking ring and connect the red and black igniter? For example, should I re-insert the bulb first, then the retaining ring and then the black and red igniter or should I pre-assemble all three and re-insert them into the socket opening as one piece? Any photos or pictures available? I have ordered a repair manual on CDs but have not received them yet. So please don't make that suggestion.
The carbon rod on the outside of the xenon lamp must enter through a groove at the bottom of the metal socket. But when it does that then the black ring (between the bulb and the red and black igniter) is not aligned to catch where it should on the same metal socket that the bulb enters. THANKS

 

I have a 2003 S500 with bi-xenon headlights. I just replaced the low beams (both sides) today. It looks a bit scary but is really easy just not a lot of working space (first time for me).

First I disconnected my battery ground cable. A lot of volts in those xenon bulbs and made certain the light switch was in the off position.

Next just remove the black cap that hides the igniter. The black cap for the low beams will be the sort of circular one closest to the outside fender. It has a little clip on the top just push that. The fun part is putting it back on. Just line it up with the little holes on the bottom and it should be ok.

Next you will see the igniter (red/black) just twist that slightly and it will come off. The igniter has a plug that will most likely come off once you twist it. Don't forget to plug it back up once you install the bulb and keep it out of the way when you are putting on the black tube.

Next is the black round tube that holds the bulb in place. This tube will also twist off (I believe counter clockwise if you were positioned in the car seat).

Then you just take the bulb out but be careful when putting the bulb back in as not to scratch it. USE SOME TYPE OF RUNNER OR VINYL GLOVES. Don't touch the bulb with your fingers.

To answer your question. I put the bulb in first and sort of moved it around slowly until it kind of locked in place. I then held the bulb in place and put the black tube over it (a sort of houdini trick) and twisted it ever so slightly until it tightened up.

Replaced the igniter, pluged the cable in and put on the cover.

Next I put the battery cable back on, started the car up and the lights worked. BUT.....there is always a BUT.

I got a "pre-safe not working message". So I rolled all of the windows up and down until they would go all the way with one touch. Did the same thing for the sunroof top, Still got the message so I plugged my seat belt in and it finally went away. I know I'm including a whole bunch of info you didn't ask for but when I wanted to replace my low beams I searched and searched the forum and could not find any detailed instructions. So maybe this will help someone in the future.

Took me about 25 minutes to replace both bulbs and as I mentioned it was a first time effort.

 

This write up you did was great!
I have also done this job before with original failure and final success.

 

Well, I ordered a replacement bulb from Amazon for $43 (see picture a box for new bulb sent by Amazon - also note Osram insert that came with the bulb). Bulb located at
I followed the helpful instructions in this thread and a video at and replaced the low beam bulb on my 2003 S500. After taking out the old bulb, the problem was a broken bulb (see picture). Happy it was the bulb and not another part such as a ballast. First time change for me, so it took about 30 minutes to replace. The new bulb looks great - like the other side headlight. Very pleased!

 

Of course, a few months after I replaced the low beam bulb on the driver's side, the passenger side went dark. I just finished replacing the passenger side following the steps above on this thread. The car has 20/20 head lights again.

 

They should always be replaced in pairs

 

The reason why they should always be replaced in pairs is because of color temperature. As HID bulbs wear, they become bluer and bluer over time. Even if you buy the exact bulb, it will be warmer than the one that has been used for many hours.