Ich_Will

About a month ago my wifes C300 started turning the headlights on and off while the switch was in the 'full on' position. The fogs remained lit as did all the running lights. Needless to say it was a bit of a surprise while driving at night. If we left the switch in the Auto position, or the off position the headlights behaved. I suspected a fault in the main switch and ordered one from the local dealer. Today i finally summoned the courage to put it in (the knee airbags were making me nervous). It wasn't a big deal at all and thought I'd share since I didn't see a DIY on this anywhere.
Start by removing the trim on the side of the dash.
https://mbworld.org/forums/attachmen...1&d=1370118089
Slip you hand in there (or have someone with small hands help) and disconnect the wiring harness.
https://mbworld.org/forums/attachmen...1&d=1370118089
Depress the three metal tabs inside to release the works from the dash (shown out of car for clarity)
https://mbworld.org/forums/attachmen...1&d=1370118089
Locate 2 small tabs at back of assembly and push out on them to release the switch from the holder.
https://mbworld.org/forums/attachmen...1&d=1370118089
Once it is loose, get that chrome trim out of your way.
https://mbworld.org/forums/attachmen...1&d=1370118219
Now, gravity becomes your friend, unless you have more than 2 hands. Hold the assembly face down and push in on all three metal tabs until the switch slides out of the holder.
https://mbworld.org/forums/attachmen...1&d=1370118219
Assmble in reverse order (noting that the chrome trim is keyed to fit correctly). Hope this helps at least one person out there...

snowmuch

Nice DIY

ktran350

Thanks for the DIY. I been having problems with my headlights turning on/off randomly and the passenger side marker staying on time to time in the off position. Dealer wanted $$ to replace. $175 and 5 minutes later its all fixed. Thanks again.

Ich_Will

Awesome! Glad this paid off for you. I didn't even want to know what the dealer would have charged for this. I gave them $240 just for the switch!

2006_C350

You have a 2010...is it just out of warranty?

Ich_Will

It wasn't consistent enough to duplicate at the dealer (in my opinion).

2006_C350

I totally agree about the duplicating part, sometimes things are hard to duplicate. There might be a tsb out, maybe you could bring the defective part in and try to get reimbursed by mercedes. It's not a cheap part.

Ich_Will

Good idea. I'll look into it, doesn't hurt, right?

C300Sport

I had the same situation. I just videoed it a few times and sent it to my SA. I had to insist, but with MB having evidence in hand, they replaced the switch without duplicating the issue at the shop.

2006_C350

I think this is a known issue...don't lie about it to get a new switch, but if it happens intermittently it happens and needs to be fixed cause this is a safety concern. There's no point to get a new switch anyways if the switch is fine.

ryson

The right side front/rear parking lights have been coming on even though the switch is in the off position. We have not experienced the headlights turning on/off on their own. Do you think this is the same problem? I saw a TSB about the SAM module being the culprit.

http://www.allworldauto.com/tsbs/NHT...in_321316.html

giovannifh

What's the part number on the switch? i need to replace mine as well and i don't think mercedes will be nice enough to replace it for free (even if it's safety related). my car is out of warranty and i didn't buy it from them.

Lindq

The part# is: 204-905-33-04

NOTE that the photos provided by Ich_Will do not clearly show that the part # is the central cylinder that, after removing from the dash, needs to be separated from the black plastic holder into which it is inserted. In his photos, he is holding the entire unit. But it is in fact two pieces. (1) The cylinder with the switch, which is the part number, and (2) The surrounding plastic "holder". This was a big source of confusion for me when I picked up the part from my dealer, then removed the entire unit from the dash. But knowing this, you should be able to figure it out when you realize that it is two parts.

The only tricky part of the replacement is reaching into the side of the dash and depressing the three metal tabs that hold the entire unit against the dash. Even with small hands, I had a challenge, but eventually got it. Once the entire unit is removed, you then need to release two small plastic tabs on the back of the unit, which will free the cylinder from the surrounding casing.

Trimud

Hello,

I am having the same problem as this guy:
I wonder which part should I order and replace:
(1) The cylinder with the switch, which is the part number
(2) The surrounding plastic "holder"

Thank you in advance!

delirium

I have a headlight issue & am wondering if replacing the headlight switch might fix it. My symptoms are:

-headlight switch is in the auto "A" mode
-headlights will flash on & off in the day time while in "A" mode
-headlisht stay on & do not flash at night in "A" mode

Thanks for your thoughts!

mike2909

Better late than never.
I would like to thank the OP for this DIY fix. I was having the same problem.
After being quoted silly money by the Mercedes dealer I decided to do this myself.
I bought a (guaranteed) complete used switch via ebay for $40 (I am in the UK) and had it fitted in less than 10 minutes. Problem solved.
Thank you again.

mike2909

If this only happens during daytime could it not be just adapting to the daylight conditions?

mike2909

I would like to thank the OP for this DIY. I was having the same problem. After being quoted silly money by the Mercedes dealer I decided to do it myself.
I bought a (guaranteed) used switch (complete switch including surround) on Ebay for $40 (I am in the UK) and had it fitted within 10 minutes.
Thanks again for the info.

Dustindustrial

My headlights have been flickering on and off on occasion, and when they do, the headlight indicator in the instrument cluster goes on and off as well, so I'm thinking it's my switch and plan on replacing it soon. I pulled up R&I instructions on All Data, and at least for my 2009, it looks like it can be done from the front, and that removing the side panel is not necessary. See the attached images.

Dustindustrial

My new switch showed up yesterday and I just came back inside from swapping it in. Thanks to the original poster, as I ended up following your instructions. Took maybe 15 minutes at most. The R&I instructions I pulled down from AllData did not work. On both my new switch, and the replacement switch, once the knob is turned to the "P" position, it would not pull out. My car has a small fuse panel underneath the side dash cover, so there was one additional step. Removing that is very self explanatory though. You just push down the tab on the top, and it swings right out.

Savage c-300

Now I'm having the same issue. I will be ordering a switch and doing this fix.

cwldf

I own a MB C180 Kompressor and I will be doing this fix. However, it seems that there are 2 different connectors for W204 headlight switch.

The old one:


The new one:


Does anyone know if they are compatible for any W204? You can find the 2 different connectors for W204 at ebay.

MB Marko

Nice DIY note to member never take the unit apart to put a sub woofer control knob in the open space lol. The place I went to suggested they do it would of been a great idea but when they opened the unit springs flew all over the place. They couldn't fix it but they paid for a new switch out of there own pocket.

Savage c-300

if you are heaving headlight problems, swap out the switch and that should solve it or sometimes just disconnecting it and putting it back together solves it too. I had the same issue with the light staying on even when the car was off and so I bought a new switch. I took everything apart and plugged in the original and the issue went away. I never even had to use the spare switch I bought.

mrtomq

My switch comes with 1 button for the front fogs. I saw a switch on ebay that has the front and rear fog buttons. Can I use this switch?