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Discussion Starter #1
Hi all
I needed to replace the biodegradable wiring on the inside of my headlight assembly - both sides - major cracking and lots of exposed copper wire - and one city light socket that just disintegrated.
I have a wagon with the self leveling system so the reservoir sits behind the drivers headlight and makes it almost impossible to get to anything. I also have big hands :grin

I decided to pull the bumper and remove the lights - Now that I have done it I cant believe how easy it is to remove. Literally 20 minutes to bumper off (note the one missed trick in the pdf) and another 10 to get both headlights out.
The full write up is in the attached pdf but here are some pics - Also I am seldom on the forum at the moment so if you have questions send me a pm too.
cheers
Barri
 

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Not to make too fine a point, but it's not necessary to completely remove the bumper cover. Just moving it forward by 3 inches will provide ample space to remove and reinstall the lights. It makes for an easier reinstallation of the cover.

I upgraded my headlights a year ago and the following are some pictures of the process.

Gurmail
 

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I have spent some time researching the biodegradable wire issue and it apparently does NOT affect 2001 models or anything newer. Stopped sometime in the mid-late 90's.

Anyone else with a 210 have wiring problems like the pics above?
 

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My wife's 98 has disintegrating insulation, but only the leads to the headlights. The rest of the car seems ok. I bought the replacement part from the dealer (2108200013), but have not installed it as my temporary application of insulating tape is still holding up.

Wiring in this specific area is a known problem.
 

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Thanks for the information! I wasn't aware of a degrading insulation issue on anything past the 124's. I'll check mine out.
 

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Discussion Starter #8
My wife's 98 has disintegrating insulation, but only the leads to the headlights. The rest of the car seems ok. I bought the replacement part from the dealer (2108200013), but have not installed it as my temporary application of insulating tape is still holding up.

Wiring in this specific area is a known problem.
Nugent x2
seems just to be a problem with the headlight wiring only and is a known problem. Probably heat related breakdown?
the rest of the wiring harness throughout the car is fine. this is just a headlight problem
cheers
Barri
 

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Thanks for the information! I wasn't aware of a degrading insulation issue on anything past the 124's. I'll check mine out.
I'm fairly certain that the biodegradeable wiring issue is specific to the M104/M119/M120 engines (W124, W140, R129). I had to deal with it on my '95 S420, but I understand the post '95 models (facelift cars) had been built with better wiring.

As for the headlight wiring, I have stock Xenon lights in my E430 and no signs of deterioration, even here in the desert. Odd problem to be sure.
 

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My 2002 E320 has the same degrading wiring insulation problem too. All the wires in the harness connectors for the headlamps assemblies driver & passenger side. My mechanic the moment i mentioned it said that he has seen his fair share of the problem. Have to rebuild/repair the harnesses as they start shorting out fuses and bulbs.
Wish you could post or pass on tips on how the bumper cover is released. Could not figure out how to remove/release mine as yet and it makes for a easier repair if, as the headlamps remove much easier with the clearance.
 

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Discussion Starter #11
Have a look at the PDF in my first post - it has a link to a youtube video on how to remove the bumper. the only part not covered is once the bumper is loose it can be wriggled off the mounting pin (picture in the pdf).
It really is easy to remove the bumper though - much easier than I thought.
cheers
Barri
 

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My '98 has this problem to the point that one of my driving ( not headlight ) lights passenger side will not light and I get the defective headlight message whenever the light switch is activated. Very aggravating. I did purchase some small gauge shrink tubing to use as insulation replacement. Not started yet. What have others done to repair the wiring?
 

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The high heat from the bulbs in the headlight enclosure and possibly because I live in warm a climate makes this a situation for most Mercedes Benz owners I know in my area. I was able to take out the wiring harnesses and pull them through the housing as the plug pops out with all the wires. Just have to know how to reroute them back when finished. I bought electrical wire and made a new harness. After I found out they are available online through eBay for a reasonable cost. About $15 each side. Compared to my time used and cost of purchasing material from Home Depot might be the better route to go.
 

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The high heat from the bulbs in the headlight enclosure and possibly because I live in warm a climate makes this a situation for most Mercedes Benz owners I know in my area. I was able to take out the wiring harnesses and pull them through the housing as the plug pops out with all the wires. Just have to know how to reroute them back when finished. I bought electrical wire and made a new harness. After I found out they are available online through eBay for a reasonable cost. About $15 each side. Compared to my time used and cost of purchasing material from Home Depot might be the better route to go.
Didn't find anything on Ebay for $15 but did for $30. Bought passenger side unit. If it is good quality, I will do the other side which isn't as bad. Thanks for the tip.
 

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USPS just delivered passenger side harness. While searching for this harness I saw that passenger side replacement harnesses were popular and readily available, but driver's side not so much if at all. Is there something unique about passengers side that creates this disintegration and the driver's side does not?

Does removal of the front bumper shroud/cover/nosepiece make this procedure much easier and worthwhile to do so? If so then I would want to replace the driver's side at the same time. Is it necessary to remove the front shroud?
 

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My '98 has this problem to the point that one of my driving ( not headlight ) lights passenger side will not light and I get the defective headlight message whenever the light switch is activated. Very aggravating. I did purchase some small gauge shrink tubing to use as insulation replacement. Not started yet. What have others done to repair the wiring?
Okay so today was the day to tackle the replacement harness event.Started to remove the bumper , but soon discovered I could remove the headlight bucked assy's without doing so. Installed the new harness and tested it before reassembly. Same symptom as before no passenger side small inboard light and no tiny bulb ( can't remember what it is called)in headlight bucket. Got out the voltmeter and tested supply side. Dead at the source. Crap. At a loss and am guessing switch or somewhere in the harness??????

Wondering if there is a separate fuse for that circuit and if so where it is located ?????
 

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There is no separate fuse but possibly combined with one of the "right" side light fuses that you can check at the driver side dash side fuse panel.

There is a dedicated wire in the harness for that light that goes all the way to the illumination control module (behind the light control knob). This wire may be open or shorted somewhere. Does the High beam and low beam work on that side ? Only the little bulb that is not working ?
 

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There is no separate fuse but possibly combined with one of the "right" side light fuses that you can check at the driver side dash side fuse panel.

There is a dedicated wire in the harness for that light that goes all the way to the illumination control module (behind the light control knob). This wire may be open or shorted somewhere. Does the High beam and low beam work on that side ? Only the little bulb that is not working ?
Yes High beam low beams both work. Inboard parking light passenger side does not. Replaced harness, checked every fuse and replaced one that was not blown but looked burnt. Now still no light but nag screen does not indicate lamp failure.
 

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The light is supplied power by the light module but make sure there is ground return path. The light's ground wire is supposed to be connected to the HI and LO Beam bulbs' ground. They work, have you checked the harness for the city light is properly grounded ?
 
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2000 E 320 White Wagon
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