Picture of bad wiring harness (400E)
 

Some of you had requested a pic of a bad harness. I had my air cleaner off today so I snapped a few pics. Hope this will help anyone that is uncertain of this problem.

This was taken on the drivers side cylinder bank, and i cut a piece of the outer coating back. Sometimes it skips a little and I most likely attribute it to this specific injector.

-Andy

WHICH YEAR....
 

Hi Andy,

Do you know when did Mercedes start using this recycleable material as wiring insulation?

not sure of year range?
 

Well to be honest im not quite sure. I know that my car was manufactured in 11/91. And most 400E and 500E owners I talk to have this problem. Im sure that there is some people out there that will know more specifics. Im guessing 92-95 for the 119 motors.

-Andy

That photo shows a breakdown that's different then what I've seen in the later (built after I think 8/92) cars, where the insulation turns to powder. Those wires in the picture simply have cracks, no?

No problems yet on my 6/02 500E (knocking on burl)

Good luck!

BTW, which/how many harnesses do you plan to replace?

I hope to just plan on replacing the main engine harness, which seems to be the one that is bad here. Yes, the wires on mine didnt turn to powder or dust, the insulation is so brittle that if u touch a wire, the insulation will just crack and fall right off.

-Andy

Here's another pic from a little while back, courtesy of Steve Brotherton


http://www.peachparts.com/shopforum/tech-help/23813-wiring-harness-pictures.html?highlight=wiring+harness

back when i saw steve's pictures i went and checked my old harness and slit the sheating in one place. the wires were not anywhere close to steve's example. in fact, they looked perfectly fine. the ends were they connected to the fuel injectors and other terminals were another story. they looked just like the picture that andy posted.

I may be wrong, but I'm fairly certain that the engine wiring harnesses on the M104 engines and the M119 engines (400E / E420 / 500E / E500) go bad for different reasons.

I have read enough posts from MB DOC and Benzmac about the insulation on the wires being changed and inherently defective on M104 engines only. I've even read the specific years (93-95) and VIN numbers in a post. There is an actual TSB regarding the insualtion problem on these M104 engines. I've seen pictures posted and seen actual harnesses in my mechanics shop. The insulation doesn't look like the one in the pictures on this post, nor on the picture that Steve Brotherton posted on the 95 E420. The M104 harnesses look like they are 2,000 years old, and the insulation has turned to dust and disintegrates in your hand. It's just gone. The problem on these M104 engines from 93-95 is systemic and all of them are either bad or going bad.

I've read enough posts to know that the harnesses do go bad on the M119 engines, but I don't believe it's the same. I think excess heat is degrading the insulation on the wires. If you go by the posts, it seems to me that a larger percentage of 500E's than 400E's go through wiring harnesses. 500E's generate more heat, thus more problems. Not all harnesses seem to go bad on these cars, too. I'm willing to bet it's a relatively small percentage. There is not even a TSB regarding an insulation problem on M119 engines.

there was an extensive post on the why's and wherefore's of the insulation problem. what i recall about it was that the new insulation compound was ostensibly bio-degradable. apparently there was not enough testing done as regards heat degradation with this unfortunate result. but then MBNA refuses to acknowledge that they did have a problem with the wiring harness. if there is a TSB on this issue, then it would not be such a hassle getting it replaced under that provision. there is a TSB with a reference to a wiring harness but it is an internal one and definitely not the main engine wiring harness.

BTW, my old harness (M104) did not have the insulation that "crumbles to dust". like i said, insulation seems intact and in good shape in most places except at the terminations where they are non-existent.

FWIW, all TSB's are internal, and they are very different than recalls.

All recalls don't have to be public and broadcast on the news, but owners have to be notified at least by mail of a recall. Recalls, by the way are for safety issues.

TSB's can be about anything - notes to technicians about how to fix something, parts changes, yada yada yada.

Mercedes should've taken care of this problem, though, once they knew there was a problem. They've created so much bad will among owners for this expensive, unexpected, and unusual failure.

I have never seen a TSB on wire harness.
Have seen the one on plug wire modification.
Do you have a TSB -ID. # on that ?
Thanks

I think I printed it out and it's at home. I'll check.

I've also seen the TSB on Alldata myself.

It talks about wire chafing and cracking. It was posted on this site before, too, which is where I got it.

What do you mean by the one on plug wire modification?

I have the All Data , but can't find that one
The plug wire one addresses the plug wire ends modification on the 124s with distributor/rotor ignition.

If you find one for harness, let me know..
Thanks..

See here for a TSB on a wiring haness problem on a '92 400E Note what is at the very top of the list, dated 1995. There are lots of others....

http://alldata.com/TSB/35/92355320.html

the TSB "95-0223 MAR 95 Recall - Wiring Harness Chafing/Shorting" (appears on 300E & 400E) is on an internal harness, not the main wiring harness. that particular one has been discussed on the forum. if there ever was a recall or even a TSB, it would be very well documented on this forum because then, the dealerships and MBNA would have to seriously pay attention to it.