how to fix a xenon light or ballast CLK W209

steveatpipex

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This post is to help people who may be having problems with factory fitted xenon lights and is based on my experience and advice from various people on this forum but all pulled togther. My particular thanks to television who made all this possible and I still have the old unit as promised if you want to contact me! Hopefully this post will help anybody with a similar problem sort it out quickly and painlessly!

Although this is based on my 2005 55plate CLK (W209) some of it will be applicable to other models. Before I begin I am assuming that you know how to jack a car up and chock it to work safely – if you don’t, stop reading now and get your plastic out and keep reminding yourself why you got a merc and it’s worth it – it will make you feel better about how much you are going to have to spend having a light fixed by the dealer!

Xenons work differently to ordinary bulbs and they need a Ballast and an Ignitor to make them work. These are electronic parts and on the CLK the ballast is a small aluminium box fastened to the underside of each light unit. The ignitor is integral to the light unit and is a red socket fastened to the rear of the bulb. Tools required – 10mm socket, torch, hand mirror, torsion driver or small flat screwdriver may work.
Ok, the symptoms – my drivers side xenon started to go on and off randomly (when the lights were switched on). To identify the problem (ballast or bulb) I swapped the bulbs over and sure enough the fault followed the bulb. These bulbs can be expensive if you buy OEM (£65 to £120). I decided to hit eBay and sure enough found a pair at £30 delivered. Some might say the cheap lamps will not last but the original factory fit lasted just over 3 years so not much recommendation there! You will need 4300k temp and they are D2S bulbs for factory fit. Although they sell higher temp (and brighter) 4300 is original spec and is will not attract attention from the boys in blue.

Replacing the bulbs. Open and secure the bonnet. Starting with the passenger side on the rear of the light unti you will see a black plastic cover that turns slightly and pulls away exposing the ignitor. Half turn the ignitor and gently pull it from the rear of the bulb. The bulb is held in place by two spring clips, unclip them and remove the bulb noting what way up it is. Check the base of the replacement bulb you will see a central pin with a rubber bung around it. This MUST be seated correctly before you install it. Replace the bulb with a new one carefully – it has notches cut out which match the holder but you will need to use the torch and mirror to make sure it is seated correctly. Use only light pressure – any force may damage the bulb. When you are sure the bulb is seated correctly, refasten the clips, again checking with the mirror. Carefully push the ignitor into place and half turn. BE CAREFUL – it is very fragile – if it does not lock correctly around the pins on the bulb, the rubber bung has become unseated and you will have to remove the bulb, reseat the rubber bung and try again. The ignitor just clicks into place when everything is correct.
Repeat for the drivers side but this one is more fiddly. Replace both plastic covers and switch the lights on. If they work, all well and good you’ve saved a lot of money by doing it yourself.

Now, the ballast. On mine at this point they lights worked for 1 mile, then the drivers side went out totally. To access the drivers side ballast jack and chock the car and remove the front drivers side wheel. You will see the inner wheel arch made up of three plastic covers. You need to remove the front and middle covers. They are held in place by some 10mm screws (metal) and 10mm nuts (plastic) and some click pins. All can be easily removed, and wriggle the plastic inner wheel arches out. You will be able to see the light unit and the ballast screwed to the underneath it is removed by the torsion driver (3 torsion bolts) or if you are lucky the small flat screwdriver will fit. Unscrew the 3 bolts and put them somewhere safe. The ballast will come away with a light pull.
To test it, you need to repeat with the passenger side wheel. Its the same process but because the washer bottle blocks access to the light unit you need to remove the light unit totally. This can only be done by loosening the front bumper bar on the passenger side. There are a number of visible bolts that you unfasten, a slider underneath the wheelarch connecting the bumper to the body (it unclips easily) and a hard to see bolt behind the front grille which you can gain access to by pulling the grille away slightly. (PM me for clarity if you are doing this).
Once this is all loosened there is a bolt to unfasten on the light unit and then the light unit can be removed by wriggling it up, forward and out. Swap over the Ballasts, reconnect the wires on the passenger light unit (no need to reinstall at this point) and see what happens. If the fault follows the ballast then it is bust and needs replacing. If not, it may be the ignitor that is broken and you will need a new light unit with integral ignitor (Probably big money or a breakers if you are lucky)

You will find the ballast to be around £300 plus at a merc dealer or the self same part at Bosch is £127 if they have any (Bosch part number 1 307 329 072). My local B
osch dealer said there was none in the country so I hit ebay again. I tracked a brand new Bosch unit down to Germany using a seller called S-cottbus. It was £115 delivered and was here in 2 days.

I put it on the car and so far so good, everything well!
A little time and effort saved me a small fortune. Total cost to me was £145 as opposed to a quote of around £800 at my merc dealer. Good luck! PM me if you want to know any more about this job, I’ll be happy to help as I can.
 

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television

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I will ask to have this moved to the DIY section :D
 

syemundo

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Great Post - Double Wammy

Thanks to steveatpipex for a great post - I'm new to the site but thought after using steveatpipex's post I would tell others about my CLK Xenon issues.

I own a CLK270 2005 model, and like steveatpipex reported I too had one headlight flickering, which went away for about 6 months, only to come back recently.

I swapped the bulbs over and the fault followed the bulb - so thought it was a bulb - got new ones, ok for 30mins until the driver's side light (with the original problem) went out completely!

Changed the Ballast - now £175 from the Bosch dealer!
Worked fine, then the passanger side started to do the same - swapped bulbs etc. but turned out to be the Ballast as well - another £175 - 2 Ballasts in one week - just lucky I guess.

Chnaged both for new ones, checked all of the bulbs including the orignal ones and working fine (So far)

Obviously a reoccurring fault on the clk which is why I thought I'd post this to help anybody else having problems.

Oh and they are OEM factory fitted Bi-Xenons and I did try swapping all of the old ballasts around to test them - definately a problem with the units!

Cheers again steveatpipex :D
 

television

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So pleased that you fixed yours, and welcome to the forum :D:D

Would there be any chance of letting me have the faulty units, I will refund the postage, and the units too you, after I have looked inside them
 

downthedustpipe

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Your Mercedes
Mercedes CLK270 Mercedes E320 Mercedes S500
CLK W209 270 CDI Xenon Fault

My CLK W209 270 CDI (2003) is giving me some grief.
The fault started some time ago with the dash warning for the right side headlight. Turn the lights on and off and it would come back on. It was infrequent and unpredictable but changing the bulb did not help.
Now the left hand side has started showing the same symptoms and sometimes both fail to show.
I am now unsure as how to test the components as none appear reliable.
My gut instinct is change the ignitors.
Has anyone else suffered this annoying problem.
Do the headlights have to come out to replace the ignitors.
Any information would be gratefuly received.
 

television

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Hello and welcome,, the headlamps normally have to come out as there is usually insufficient room to work with them on the car
 

wireman

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nice 201 2.5D 1993 & very nice 129 SL500 1994
A warning,

HID lamps require a very high voltage to strike, it's in the region of 2000 to 4000 volts for a cold lamp and as high as 25 to 30kV for a hot lamp, this is not of sufficient energy to cause death but it will certainly hurt if contacted resulting in a serious risk of injury (typicaly you fly off the high voltage and stop against something hard) if the lamp wires are touched during the switch on. Given the right circumstances 25kV will jump an inch or so.
Any damp in the lamp wiring may cause the loss of the ignitor voltage so be sure that the wiring is well sealed.

Take care not to touch the lamp wiring whilst attempting to troubleshoot HID lamps.
 

downthedustpipe

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Mercedes CLK270 Mercedes E320 Mercedes S500
Left Xenon has now given up the ghost. Do you still have any information regarding the removal of the w209 headlights/ignitors. There would appear to be some compatibility of parts from other vehicles (BMW Ford Mazda) for these xenon headlights but has anyone tried using the cheap xenon kits.
I am very sceptical.
It is due an mot at the end of the month so i need to pull my finger out. (just replaced the blown radiator on my 3.5 Shogun)
Any advice to smooth the job gratefully recieved.
 

television

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It might be easier to have a spare lamp, rather than disturbing the good one and swapping
 

downthedustpipe

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Mercedes CLK270 Mercedes E320 Mercedes S500
The previous owner of this vehicle "lived with" many niggly problems (machine gun locking, cracked speaker grill in driver door, curbed alloys, unpredictable cd player) that I have now fixed. I like my cars to be perfect and this is the last item on the "to do" list.
My problem is that this is my first car with xenons and lack of experience is holding me back.
The car is used regularly so i want to be prepared so the job can be finished swiftly.
The ballasts are fairly easy to change, but are the ignitors fixed in the light unit or can they be easily removed/swapped.
 

television

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The igniter can be changed from the Bosch ballast unit, you can buy them on Ebay much cheaper than from MB there is a Bosch part number on the box

If you need the bumper removing instructions i can send those to you
 

downthedustpipe

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Thanks, the bumper removal info will be useful.
I think I am going to do offside and nearside at the same time as they are both playing up and remove them to make the repair.
Thanks again for your input.
 

television

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I have the front bumper info already printed off and I can send it to you now,,just need your Email address that you can edit out later,,I will be going to bed in 15 mins
 

television

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209 front bumper remove paper sent you can edit out your address
 

command

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Clk 209 xenon ballast

Fix ballast alittle hard ,

suggest chage it .

Mercedes-C-OEM-Xenon-Ballast.jpg


like this ,hope can help you .
 

Nickels99

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CLK500/2005/5.0l
Television: I stumbled upon this old thread and have the exact same issue with my 2005 CLK500 (W209). I cant thank you enough for posting this! Would you be able to send me the bumper removal instructions as well?
 

tottenhamboy

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change from xenon back to halogen

The n/s dipped zenon died on my 05 A class ( w169). On checking I found the bulb and ignitor had fried. Replaced both but no go, so I spent the morning at local MB dealer and they gave me a bill for £120 and an estimate £750 for replacing the headlight assembly! saying there must be a short in the headlight wiring which is not reparable. So, I've already spent £250 and still don't have a light.
I don't do a lot of night driving , and I just found halogen replacement headlights from nationalspares.co.uk at £150 a pair!
The question is, are the units compatible ? Can I just remove the xenon headlight assemblies and replace with the halogen ones?
And thinking about it, I don't suppose there's a way of keeping the original units and replacing the xenon bulbs with halogen ? no, surely that would be too easy!
 

nandomore

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CLK/2003/270 CDI
Hi, can anyone help me with the removal of the Ballast from a CLK 270 CDI W209 2003?
thanks
 


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