C-Class (W204) 2008 - 2014: C180K, C200K, C230, C280, C300, C350, C200CDI, C220CDI, C320CDI

Rusty ground wire to rear lights block

Thread Tools
 
Search this Thread
 
Rate Thread
 
Old Feb 7, 2024 | 02:51 AM
  #1  
uchu47's Avatar
Thread Starter
Junior Member
Liked
Loved
 
Joined: Feb 2024
Posts: 52
Likes: 3
From: Thailand
C230 W204
Rusty ground wire to rear lights block

Got a faulty rear light message yesterday. After checking the block all the bulbs were ok, but ground(?) wire completely rusty and half melted, causing intermittent contact.
Managed to carefully clean and press contacts together and it works (for how long it remains to be seen).

After reading a while about it, it seems like a very common issue for W204. In some countries it was considered a recall. Opened my other rear block - the ground wire is in same condition.

Whats the best way to deal with it? I have ordered new plugs with a proper thickness wire so thinking replacing original ground wire all the way (if it is doable without dismantling half of car - not sure how long it is) or at least the part coming into the plug, while soldering it to debris of old original ground wire.
Reply
Old Feb 7, 2024 | 06:53 PM
  #2  
TimC300's Avatar
MBWorld Fanatic!
Community Builder
Liked
Loved
Community Favorite
 
Joined: Aug 2023
Posts: 3,689
Likes: 1,111
From: MA Coast
W204 2010 C300 4matic Sport M272
What year W204?

Im not sure what the "block" is, and you write that the ground wire is completely rusty and half melted. The entire wire? photos would be helpful.

I would just remove and replace the damaged parts. if its just a rusted connector inside the harness then remove that connector and crime on a new one and put it back in the harness. if you need to remove some wire just cut it and add some new wire so its the right length again. I like to solder all my wires then cover with heat shrink

Below is for 08-11.











Reply
Old Feb 7, 2024 | 10:04 PM
  #3  
uchu47's Avatar
Thread Starter
Junior Member
Liked
Loved
 
Joined: Feb 2024
Posts: 52
Likes: 3
From: Thailand
C230 W204
thank you. My W204 is 2009. Sorry for not including a photo - didn't make it on the spot but below is online photo, mine was exactly same, slightly worse condition.




4 bucks per pin is a rip-off but no seems like no choice. Will ask local dealer with part numbers - thank you
Reply
Old Feb 7, 2024 | 11:30 PM
  #4  
TimC300's Avatar
MBWorld Fanatic!
Community Builder
Liked
Loved
Community Favorite
 
Joined: Aug 2023
Posts: 3,689
Likes: 1,111
From: MA Coast
W204 2010 C300 4matic Sport M272
Hopefully you dont need a new carrier, but if you do they are only around $22 and come with new bulbs so thats a plus.

The connector at the Mercedes dealer near me is $4.20 each. Or search online for "Molex Female Connector" and see if you can find the right size, I dont know the specific size so not any help. Or ebay has a few options.








Reply
Old Feb 7, 2024 | 11:39 PM
  #5  
TimC300's Avatar
MBWorld Fanatic!
Community Builder
Liked
Loved
Community Favorite
 
Joined: Aug 2023
Posts: 3,689
Likes: 1,111
From: MA Coast
W204 2010 C300 4matic Sport M272
I forgot to mention you should check to see if any water is getting in your trunk that caused this issue. I recently resolved water getting in my trunk by replacing the rubber-type fasteners that hold the trim on.

Here's the post I made about it with photos and part #'s. https://mbworld.org/forums/c-class-w...ar-window.html



Reply
Old Feb 8, 2024 | 11:33 PM
  #6  
uchu47's Avatar
Thread Starter
Junior Member
Liked
Loved
 
Joined: Feb 2024
Posts: 52
Likes: 3
From: Thailand
C230 W204
thanks a lot @TimC300 ! It seems to be purely related to electric as only ground cable is destroyed. all other ones are in good condition. Will either replace whole set or go as some youtube video suggest by soldering proper wire to ground on light cluster and putting it to ground pin next to fuse block.
Reply
Old Feb 9, 2024 | 03:07 AM
  #7  
Just204's Avatar
Super Member
 
Joined: Jun 2016
Posts: 562
Likes: 75
Mercedes w204 4matic sport
Originally Posted by uchu47
thanks a lot @TimC300 ! It seems to be purely related to electric as only ground cable is destroyed. all other ones are in good condition. Will either replace whole set or go as some youtube video suggest by soldering proper wire to ground on light cluster and putting it to ground pin next to fuse block.
I just had this a couple weeks ago. You will need a new bulb carrier( didn’t come with bulbs), new connector, and what we carr a pigtail to replace the wire(that’s the killer, dealer charged $17 for it but I had to, a police ticket would be a lot more). Supposedly the ground wire isn’t fully sufficient for the tail light, so it gets overheated and melts. Mine has lasted 11yrs so I’m not too scared about it but you can also solder a new ground off the carrier. A number of people use a heavier gauge and they say that it’s a Permenant fix. Being an ex dealer tech I prefer the official repair only, but may make a second ground. This is not from water damage so don’t worry.
Reply

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 


You have already rated this thread Rating: Thread Rating: 0 votes,  average.


All times are GMT -4. The time now is 12:56 AM.

story-0
6 Mercedes Models That Did NOT Age Well (But Are Somehow Still Cool)

Slideshow: Not every Mercedes design becomes timeless, some feel stuck in the era they came from.

By Verdad Gallardo | 2026-05-12 18:09:07


VIEW MORE
story-1
Manual Mercedes? 6 Times Sindelfingen Let Drivers Have All The Fun

Slideshow: Yes, Mercedes built manual cars, and some of them are far more interesting than you'd expect.

By Verdad Gallardo | 2026-05-02 12:36:58


VIEW MORE
story-2
Mercedes SLR McLaren 722 S Is Extremely Rare Example Modified by McLaren

Slideshow: A one-of-one U.S.-spec Mercedes-Benz SLR McLaren Roadster became even rarer after a factory-backed transformation at McLaren's headquarters.

By Verdad Gallardo | 2026-04-29 11:19:28


VIEW MORE
story-3
8 Classic Boxy Mercedes Designs That Have Aged Like Fine Wine

Slideshow: Before curves took over, Mercedes mastered the art of the straight line, and some of those shapes still look right today.

By Verdad Gallardo | 2026-04-25 12:05:49


VIEW MORE
story-4
Flawlessly Restored Mercedes 190E Evo II Heads to Auction

Slideshow: The 190E Evolution II shows how a homologation necessity became a six-figure collector icon.

By Verdad Gallardo | 2026-04-22 17:53:47


VIEW MORE
story-5
Electric Mercedes C-Class Unveiled: 11 Things You Need to Know

Slideshow: Mercedes is turning one of its core nameplates electric, and the details show just how serious this shift is.

By Verdad Gallardo | 2026-04-21 13:58:06


VIEW MORE
story-6
Mercedes EQS Gets A Major Update: Everything You Need to Know

Slideshow: Faster charging, longer range, and a controversial steer-by-wire system define the latest evolution of Mercedes-Benz EQS.

By Verdad Gallardo | 2026-04-15 10:35:34


VIEW MORE
story-7
5 Underrated Mercedes-Benz Models That Don't Get the Love They Deserve

Slideshow: These overlooked Mercedes-Benz models never got the spotlight, but they quietly delivered more than most remember.

By Verdad Gallardo | 2026-04-13 19:35:45


VIEW MORE
story-8
Mercedes 300D Has Pushed Well Past 1 Million Miles and It Ain't Stopping

Slideshow: A well-used 1991 Mercedes-Benz 300D with more than one million miles is now looking for a new owner, and it still appears ready for more.

By Verdad Gallardo | 2026-04-10 10:05:15


VIEW MORE
story-9
10 Most Reliable Mercedes-Benz Models You Can Buy Used

Slideshow: From bulletproof sedans to surprisingly tough SUVs, these Mercedes models proved that the three-pointed star can go the distance.

By Verdad Gallardo | 2026-04-08 09:55:49


VIEW MORE