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Discussion Starter #1
It is clear from the number of posts here on this topic that this item gives many of us a problem. Even if you have not already experienced a cracked third brake light (officially termed ‘center high-mounted stop lamp’) on your W209 CLK, the chances are that sooner or later you will. The design of the unit seems unable to tolerate the successive shocks that its mounting on the trunk lid is bound to inflict.

Tip: don’t slam the lid.

Editor's note: Repeat, Don't Slam the Lid! Close it gently but firmly, applying pressure only as it latches. This prevents the cracked brake light in the first place!

It is not difficult to replace the unit should you have to, even for the most inexperienced novice. Here’s a bunch of photos that I took when I replaced my cracked brake light recently. If your M-B warranty has expired, this shows you how it is easy to changeout the brake light yourself.

Image 1
my cracked rear brakelight, held together with transparent tape.

Image 2 - Parts required.
new third brake light assembly (part numbers differ according to manufacturer)

Image 3.- tools required
1. 10mm open end spanner
2. Torx 20 screwdriver
3. Pliers
4. Regular screwdriver

Open the trunk lid. Unlock the warning triangle and remove it.

Remove the warning triangle bracket, which also anchors the inner cover. This is held by a ‘spreading clip’, and to remove this you must prise up/out the center pin using a small screwdriver, and then ease out the outer clip with the screwdriver and pliers. These can be re-used so put them to one side.

Slide the bracket to the left, and use a small screwdriver to lift the inner plastic clip to free the bracket. This reverse image shows the fixings and the clip to be released on the bracket. Image 4.

Remove the trunk lid cover. To do this the 10 spreading clips that retain the cover must first be removed as described above. Image 5.

(continued)
 

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continued...

Remove the single spreading clip on each hinge lever, and also pop the plastic clips holding the hinge lever covers on both sides to free the top of the trunk lid cover.
Image 6


Use a torx 20 to remove one screw (and loosen the other) holding down the lid release plate, and pull the cover edge over the lid buffers and free of the lid.
Image 7, Image 8.


Now the entire inner cover can be removed from the trunk lid, revealing the center brake light assembly.

Image 9, Image 10.

(continued)
 

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continued

The brake light assembly is secured by a bracket held in place by two 10 mm nuts. Remove and retain the nuts as the kit does not include new ones, and detach the bracket. The brake light assembly can then be removed from the outside of the trunk lid. It is easier to disconnect the cable when the brake light is partially removed from the trunk lid. Press the lugs on both sides of the connector inwards to release the lock and pull the plug out of the socket. The brake light can now be removed.

Before the new brake light is installed, the white seal protecting the adhesive foam surrounding the brake light should be discarded. Image 11.

Install the new brake lamp through the space in the trunk lid, and re-fit the connector ensuring that it is locked in position. Attach the bracket using the two screws, being careful here not to over-tighten. Finally ensure that the lamp is seated flush with no gaps at the surface, as it must form a waterproof seal.

Refit the trunk lid cover in the reverse order to the above, making sure that the cable in one hinge lever is routed correctly under the cover before clipping it secure.

Image 12. New third brake light installed



On first switch-on to confirm that the new light works, the cluster may throw a few fault messages. Switch off and re-start the engine, and hopefully the error messages will have cleared themselves. Job done.
 

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Thanks but Why?

Thanks for the info on how to replace the lamp unit yourself, however.
Surely this is a MB design fault on the car and the lamp is not fit for purpose.
I have had three failures on my CLK320. You would not expect this kind of fault on a Honda or Ford. Why should we expect it on a MB? MB should replace free of charge regardless if they want to retain customer loyalty?!!
 

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Discussion Starter #6
I've been giving this issue some thought, and I believe that the problem really lies with the vehicle owners (or their family) slamming of the trunk lid too hard. The dynamic shock to the 3rd light is probably in the range of several G's.

The fracture of these plastic lenses would not be from thermal stress. Maybe the lid buffers could be redesigned, but my solution would be a warning sign on the trunk not to slam the lid excessively.

Some MB models have a power-operated trunk lid. It would be interesting to know the survival rate of any rear lights mounted on that.
 

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Thanks Key, I've noticed that because of the automatic trunk release the lid needs added effort to close. I have been slamming to ensure the lock engages.

I will treat it like I treat the engine hood and apply pressure to close it from now on.

Thanks for the warning.
 

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I've been giving this issue some thought, and I believe that the problem really lies with the vehicle owners (or their family) slamming of the trunk lid too hard. The dynamic shock to the 3rd light is probably in the range of several G's....
This is entirely possible. However Keyhole...just for the sake of argument...:)...Don't you think MB should have taken this into consideration somewhere along the line?
 

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Discussion Starter #9
I do - but where should they draw the line? Mine did not crack until my car was over 4 years old and outside the MB warranty period (in the UK).

I think that hundreds have been replaced free by MB in the US.
 

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Keyhole, Thank you so much for the very clear instructions on the 3rd light replacement. I now have to do mine. However, as I do not wish to mortgage my home, and in addition, pledge my 1st. born, where would be a good place to buy one. Have found nothing on the net at less than about $140. Any thoughts??
 

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Discussion Starter #11
Hi davimack - I agree that parts like this cost the earth at the dealership. :eek: But I don't trust the alternatives from the Far East - or wherever.

I just suck it up and console myself that I save money every time I do a job on the car myself, and so far (in my 4 years of MB ownership) I have not spent a penny on MB workshop labor. These cars can be very expensive to own, unless you go the diy route, whenever possible.

ps - my 3rd brake light was held together successfully for 12 months with transparent sticky tape!
 

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Hi all,
I'm new to this post and do not have issues yet with the 3rd stop light on my wife's 430.....But I did want to comment on the mention of the cost for this item, which I just learned when reading this post. Somebody please tell me how in the world anybody can justify charging $140 dollars for a piece of cheap plastic? I find this utterly sickening if that really is the case! I will definitely be very careful with the trunk from now on. Glad I'm handy when DIY'ing things on my cars as well.


Steve
 

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Steve

I remember complaining about the price of a OEM car component many years ago, for an old VW Beetle I believe.

The parts guy said: "We have to hold hundreds of bits in this store, for many models of different years, just in case someone like you comes in one day wanting it. We may never sell it, but we still have to hold it".

So it's not really anything to do with the cost of manufacture, it's simple economics ....
 

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any one got any links on where i can buy this light from?

i have a 2003 clk500 coupe and have been quoted by dealer for $244 Canadian which is absolute rip off.

Any help finding me a link guys?
 

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bulb replacement

Hi all, new to the site
just wanted to know if some of the bulbs in the 3rd brakelight be changed or do you have to replace the whole light?
cheers

Harby D
 

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It's an LED (light emitting diode) - ahead of its time!

So no bulbs. Easy to replace - I did mine - and without completely removing the trunk liner. I say swallow the parts cost - knowing full well you got into this when you bought an M.B. That's why we love them - :)
 

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What a great DIY tutorial. Thanks for that, but I had a few questions. I have the standard cracked third brake light on my CLK 500 and have ordered a replacement part. Is the piece I ordered (209-820-10-56-M22) the plastic piece or the plastic and the led lights? Are there two separate items needed to replace the cracked light? Taillights work fine, just the plastic is cracked. Just want to make sure I have the right parts for the job.
 

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Discussion Starter #18
niscuit - you have ordered the right part.

It comes in a box as one complete assembly, but you do have to re-use the existing two nuts that secure the original part. There's no torque given in the WIS for tightening these - you just have to use your intuition....

I note our friend Rosswell managed to change his unit recently without completely removing the trunk inner lining. You probably can, but I took it out anyway.
 

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niscuit - you have ordered the right part.

It comes in a box as one complete assembly, but you do have to re-use the existing two nuts that secure the original part. There's no torque given in the WIS for tightening these - you just have to use your intuition....

I note our friend Rosswell managed to change his unit recently without completely removing the trunk inner lining. You probably can, but I took it out anyway.
Thanks for your help once again. You're the man!
 
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