w204 rear light cluster problem

[SheriffJW]

Is this a simple disconnect battery and then diy job?

Mines nsr.

 

[bestwah]

Tail Lights

Guys
Read all the comments and cant seem to find anyone explaining the issue I have. I have just noticed my rear tail lights on the drivers side are working but seem dimmer than the rear tail lights on the passenger side. I have replaced the bulbs on both corners but this has done nothing. can anyone tell me if this earth issue is the cause for my light issue. Thanks in advance.

 

[television]

Guys
Read all the comments and cant seem to find anyone explaining the issue I have. I have just noticed my rear tail lights on the drivers side are working but seem dimmer than the rear tail lights on the passenger side. I have replaced the bulbs on both corners but this has done nothing. can anyone tell me if this earth issue is the cause for my light issue. Thanks in advance.

It could well be, but you do need a a voltmeter to measure.

Connect the meter to the + and there should be 12v, then the - and there should be zero voltage, if you have anything much on this line then an ground fault

 

[nrg220]

rear lights

Its an earth problem. Primarily the earth pin and is a well known problem. Its solved by replacing the earth pin on the small plug in socket on the light cluster as if you unplug it its likely you will see it blackened. One side of mine was so bad i had to replace a light cluster as well. I havent done it but the longer term solution would be to drill the cluster and make a better earth connection as obviously the earth pins are not goof enough. I dont have the part numbers for the pins but they are replaceable without soldering etc. Its been a year or so ago so if you need anymore detail let me know but go and look at that connector on your cluster

 

[Harryspotter]

Sid300sl

Hi sid I wonder if you could show exactly how you fixed it. My lights have packed in and the brown wire has turned black?

 

[ernieh]

Post 9 in this thread gives a good description of how to go about this job. Probably best to get the parts before you start; i.e. lampholder, a couple of nipple connectors, plug to connect between loom and lampholder and straightened out paper clip.

You only need to cut the brown wire back 10mm to get rid of the burned section, but make a careful note of the wiring order in the socket noting that the plug is handed.

An autoelectrician would sort it for around £100 if they charge £45 per hour as they do around here.

Ernie

 

[nrg220]

burnt BROWN earth wire

The brown wire is the earth oddly enough. If the wire has gone black there is a good chance the terminal in the plug is screwed. These are replaceable, if its burnt on the light cluster chances are you will need a new one, I did.

You can go into your Merc dealer as i can tell you the parts guy will know exactly what your talking about as its a common and well known problem, if your lucky you can just replace the pins on the brown wire, they are not soldered but maybe they should have been. The plug does come apart

When your in the boot and pull off the plug on the rear light shine your torch and Check the male part of the connector in the light cluster if its all badly burnt and deformed you need to replace it. Check the other side too. I had to replace one light cluster only and the two pins. What it really needs but i havent done it is for this brown cable to be bolted through the light cluster earthing metal plate. Its been 18 months now and just checked mine, still ok but you maybe have heard the new C class in the USA has been having smoking boots, same problem, dodgy earths and probably the autos? Is your an auto as then the brake lights are used more often

 

[nrg220]

a get out solution

As one chap said just connect the brown wire to a good alternative earth, there is one on the side of the wing if you have a look. A group of brown wires bolyed to the side. Mercedes fix of £280 someone said? They must be having a laugh especially as its poor design and totally down to them plus all they will do is replace the pins and cluster probably. In the USA they fix for free but not here seemingly

 

[television]

It must be the same guy that does the rear end electrics, and past his sell by date.

Leaving the wire size out of it, the connector plays a big part in this as the connector has to handle some 6.8 amps with everything on, most of us know the effect on a loose wire in a mains plug where the connection is not good and the first few inches of the cable become brittle and melts.

There is a way round it, do not drive the car at night in the fog,while indicating and reversing, take a different route home to avoid this.

Side lamp 5W
brake lamp 21W
reverse lamp 21W
indicator lamp 21W
Fog lamp 14W

 

[nrg220]

Not using the car in some circumstances seems a bit drastic and a pain i would say, its supposed to be a Mercedes after all. Once rectified as per earlier post you will be fine as mine 18 months later is still good although i will check it occasionally.

Its annoying for sure as it was never an ideal solution at the point of the factory. Its not as big a problem to fix as you may think and providing your a bit adept at DIY then its simple enough and no i didnt disconnect the battery as no need to. Remember yes although the wire may exhibit blackening its also often the male and female connectors are fried.

The female is just a replacement pin, the male pin if fried may need a new light cluster as its fixed into the cluster. Good luck

 

[granty166]

intermittent electrical fault :-(

Hi, I'm new to this forum and to M/B ownership, having a similar problem with my c220 cdi, it is the older w203 model though so dont know if any body has experienced any of these symptoms, basically I have an intermittent fault which affects my tail lamps and rear fog lamp but not my brake lights? and when the fault occurs it also affects the electric seat adjustment, the rear window heater and the auto boot opening function !! really frustrating considering the days are now getting shorter and need to drive at night. I've checked all the fuses, bulbs and holders and they seem fine, I cant justify taking it to a garage as they will probably charge me more than the car is worth. I'm capable of repairing myself, however diagnosing the problem I am not!! please please help!!

 

[television]

This could be a bad earth wire, or the rear SAM, A star read out might say.

 

[GioC]

This problem brought me to this forum.

I have the same issue with the classic scrolling error message "Tail Light R, Substitute Lamp On > 3rd Stop Lamp, Check Lamp > Number Plate Light"

I have swapped the lighting cluster over to the other side to make sure that the cluster wasn't faulty it worked fine but when I put the other cluster over, that played up.

Like you guys have pointed out, probably looking at a short in the circuit somewhere. The pins within the cluster are fine (obviously as they work on the other side) and the pins within the plastic plug unit "seem" fine and not burnt out.

The fact that the problem comes and goes would most likely indicate a damaged wire, possibly faulty earth somewhere.

Going to take it for a diagnostics to an independent Merc garage because at Merc prices, it would probably cost more than the car!!

 

[GioC]

This problem brought me to this forum.

I have the same issue with the classic scrolling error message "Tail Light R, Substitute Lamp On > 3rd Stop Lamp, Check Lamp > Number Plate Light"

I have swapped the lighting cluster over to the other side to make sure that the cluster wasn't faulty it worked fine but when I put the other cluster over, that played up.

Like you guys have pointed out, probably looking at a short in the circuit somewhere. The pins within the cluster are fine (obviously as they work on the other side) and the pins within the plastic plug unit "seem" fine and not burnt out.

The fact that the problem comes and goes would most likely indicate a damaged wire, possibly faulty earth somewhere.

Going to take it for a diagnostics to an independent Merc garage because at Merc prices, it would probably cost more than the car!!

A quick update to this, I emailed VOSA as suggested per this thread and told them of this. They said the following..

"We are aware of the issue with the Mercedes Benz C Class and have
previously investigated it. We have concluded that the connection block
fails as a result of high resistance in the connections which is due
electrochemical corrosion or liming, this issue is accelerated by the use
of dissimilar metals. However, the driver is made aware of the issue on
the vehicles instrument panel, other lights on the vehicle provide notice
to other road users of the vehicles location. Additionally, MB have stated
that there is not a risk of fire and they are taking a pro-active action
with reports of this issue.

We would therefore suggest that you contact Mercedes Benz Customer Service."

Fair do's, very quick reply.

Well I know it isn't the connection block as it works perfectly on the other side. Have checked the cable throughput with a multimeter and not really getting any differences, either side has good current throughput... No liming within the connectors either.

The fact that it worked and stopped (and worked for a few days again after a little wd40 sprayed within there) tells me that it isn't a burnt out cable, though the WD40 could also be a coincidence.

Hopefully when I take it in on Thursday we should get some sort of diagnosis and I'll place it on here.

Thanks for the tips within this thread guys, they did come in helpful in ruling things out.

 

[GioC]

Today car went to Independent Merc garage and they ran tests on it. It ended up being the rear sam at fault as they had a spare (faulty) one in the shop and tested that. Different errors but my errors gone.

Mercedes want £265+vat for one of these?? Are you having a laugh!

Chose to go with a second hand one with 6 months warranty offered for £50

That's £66 for diagnostics and testing + £50 for rear sam + £50 for reprogramming (second hand) unit and fitting = £266

Not sure if it is wise or not to go for a second hand unit and hope it wan't a false economy.

 

[television]

The SAMs are not a real problem on the 204's, you should be just fine.

 

[athakrar]

Hi

I've just come across my C Class 2011. An car electrician told me its a common design problem which causes the cluster casing (plastic bit that holds the bulbs) to overheat. I googled it and the car has been recalled in US and Canada.

Some MB garages have replaced it FOC, mine in Leicester havent and wanted me to book it in for an inspection and charge £114 just for that. My electrician fixed it for £45 and says its better than the MB replacement as the same thing can happen again.

So, try your dealer first, and consider an uto electrician. There's a YouTube video on the issue and a fix for those of you DIY minded. Shame that MB haven't just sorted it here in UK when they clearly know its a problem.

 

[Benzed out]

Rear lights acting silly

I've had A problem with my rear lights!
Please help as this is driving me mad
The front & mirror indicators flash as normal yet the instrument cluster flashes rapidly, when this happens the rear indicators don't work or reverse lights.
This also plays havoc with my headlight switch causing my front fog lights to go off, The fuel gauge also plays up at this point and the rear demister fails to work.

I checked the rear light clusters and the bulbs had started to melt at contact point because of overheating so I replaced all the bulbs and cleaned the contacts on the cluster. However the wiring and connectors seem to be in tact.
The bulbs get hot and the rear SAM unit located close to the drivers side rear light in the boot has several relays that are quite hot also.

The lights do work as normal for a short while when engine switched off for a while but then play up again at random.

My W204 has done some miles but that shouldn't be an issue

Any help will be appreciated thanks

 

[A.J.]

This is likely to be the known bad earth problem, if you read the previous posts on this thread the answer should lie within those pages.

I had the same problem about a year back but not any where so dramatic as your are experiencing and it was simply the off side rear earth that was corroded.

 

[drip.feed]

Now it's my turn. 2010 W204, 103,000 miles.

All left-hand-side rear light cluster bulbs were being reported as blown. It got worse and worse over the period of about a month.

I did what this guy did and it is all working A-OK now:

If you have a good soldering iron, and aren't a ham-fisted klutz, you can easily tackle this yourself.

Here is what my near-side and off-side connectors and light clusters looked like before I re-earthed them.