Melted headlight plug on W124 - PeachParts Mercedes-Benz Forum

BodhiBenz1987 · #1 12-30-2012, 04:47 PM

When I went to change out my headlamp bulbs (one was going out occasionally; decided to change both for consistency), I found one of the connectors in pretty rough shape, melted and corroded. I didn't have any problems with the light before, but when I tried to put it back on, I get very little or no light output. On searching I see that melted sockets aren't that uncommon on the w124, so I just figured it is time to solder a new one in. Anyone happen to know a part number for that harness? I scoured the EPC but can't seem to find it. I noticed AutoZone carries plugs that would fit, but I'm concerned about quality ... thoughts? Of course I can always try to find a good used one ... I can't believe there aren't any in my three big boxes of random w124 connectors!
The plug in question is pictured below.

layback40 · #2 12-30-2012, 07:15 PM

The contact surfaces are originally silver coated brass. When the silver is lost by corrosion/arcing the connection starts to get hot. If they are not too damaged, you should be able to dismantle the plug & socket to clean the pins & other bits. If you give them a good clean, tighten the contacts & coat with some sort of anti corrosive paste, they will normally give good service.
Where I am, dust gets into every thing & vibration then makes it like sand paper, then when moisture gets in, things dont work. I have 150/100 watt globes, the extra current & associated heat makes the problem worse if I dont keep right on it.

Fulcrum525 · #3 12-30-2012, 07:31 PM

I have a similar issue with a headlight on the G. Upon close inspection sure enough the plug was partially melted. I also tried the Autozone route as the H4 plug looked pretty universal. The box said "Made in India" and one look at the contents made me very uneasy as it looked flimsy. Thankfully the box could be opened so I went into the truck and grabbed a spare H4 to try it out. Sure enough I couldn't even get the light to fit into the plug

I ordered a real MB plug and the light clicked into place on the first shot. (The only problem is that I still haven't had time to rewire it.) After this last snow storm though i'm going to do it AND get the fog lights reconnected

auspumpen · #4 12-30-2012, 07:46 PM

I believe that plug is just a standard DOT 9004 unit, so your local wrecking yard is probably full of mid-'90's vehicles of all stripes with a suitable splice-in replacement. Do yourself a favor and just upgrade to Euro E-code lights and be done with that problem forever.

jay_bob · #5 12-30-2012, 08:52 PM

Wow you just can't catch a break in the electrical....

In the headlight assembly, the vehicle harness plugs into the back of the housing and there is a sub harness for the lights inside.

If you grab a 124 headlight housing at the yard you will get a new wire pack and sockets inside. I would not mess with trying to make a splice inside the housing.

If you only have the option to replace the socket, solder and heat shrink is the only method that will survive.

BodhiBenz1987 · #6 12-31-2012, 01:25 AM

Thanks, guys. I guess I'll see if someone in the parts forum can pull the whole harness out of a light for me. I do have a spare light housing sitting around, but naturally the headlight section of the harness was already cut out when I got it. But at least I can see how it's all in there.
Frustratingly, I discovered this all right before I holiday, when the dealer is closed and I can't get anything shipped. Of course I can drive the Jeep so it's not the end of the world to wait. In the meantime I'll work on cleaning up the nasty patch of rust on the ground cluster behind the light.

MBeige · #7 12-31-2012, 01:40 AM

We had the same problem in my sister's 190E. Installed a surplus/used connector from my mechanic's spares and all is well. We did notice the drop in light output.

More reason to go with European headlamp assemblies? I've never heard of this problem on the H4 plugs.

BodhiBenz1987 · #8 12-31-2012, 01:53 AM

I have considered euros. I have them on the W123 ... it was a no-brainer there and would be for pretty much any other car. They look (and perform) really sharp. That said ... I know this is going to sound totally nuts, but the U.S. headlights are really a part of Bodhi's "face" as I've known it for 25 years, and I don't really want to change it.
I suppose if I found a perfect pair of euros for a reasonable price, I'd give them a try down the road. They might grow on me.

MBeige · #9 12-31-2012, 02:07 AM

I had the same concern about my 300D W123 when switching to Euros, but then again I only had my car for 4 years only when I converted to Bosch Euro lights.

Problem with the W124 is that they do not have an option like the W201, W123 and W126 do that allow H4 replacements in an older headlight design. The W124 used the same headlight design up to '93 and this design did not use sealed beams. In the W201 and W126 "bucket" or older style lights w/ sealed beams, there is the option to replace with H4 lenses that fit in place of the sealed beams. This keeps the original look but functions like the European light assemblies do.

Another thing that strikes me is that the US lights output is only 45W in low beam, but the standard Euro lights have 55W in low beam. The 10W additional light output, in a stock configuration, with a lens pattern that puts the light where you need it, was a no brainer to me and made me realize it's time to switch, when I converted the W201 and W124 to Euro lights.

300D-91 · #10 12-31-2012, 04:29 PM

You could buy something like this.

It's designed to withstand the heat of 'off road' bulbs. In your case you would use it for a replacement socket.

BodhiBenz1987 · #11 01-01-2013, 04:10 PM

I ended up getting a harness from the dealership, which is actually a harness from NAPA. They said they aren't available from MB, so they use the NAPA ones. It looks sturdy enough and I've done well with various things I've bought from NAPA in the past, so I'll give it a try. They also gave me butt connectors with solder already in them as well as heat shrink. We'll see how it goes.

charmalu · #12 01-01-2013, 07:12 PM

Are these Butt connectors the type you crimp? It would be best to solder the connections. solder is for continuity. then heat shrink the connections.

Charlie

BodhiBenz1987 · #13 01-01-2013, 07:41 PM

Quote:

Originally Posted by charmalu

Are these Butt connectors the type you crimp? It would be best to solder the connections. solder is for continuity. then heat shrink the connections.

Charlie

I can post a picture of one tomorrow ... they aren't supposed to be crimped ... you feed the wire in either end and apply heat to melt the solder that is built into the tube. I guess it's kind of soldering for dummies. I also have traditional solder equipment I can use, but I'm terrible at soldering. Though I did fix my 240D's side marker successfully using solder.

babymog · #14 01-01-2013, 08:06 PM

Crimp is better, solder has a higher resistance than the wire or connector. Solder isn't a bad fail-safe after crimping.

Woody Worker · #15 01-01-2013, 08:41 PM

Quote:

Originally Posted by babymog

Crimp is better, solder has a higher resistance than the wire or connector. Solder isn't a bad fail-safe after crimping.

I wonder why those crazy German engineers at Mercedes elected to use a more costly, complicated and inferior electrical connection system for the billions of automotive connections that they've been making in all these vehicles all these years?