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Oh boy: car needs a new harness (help)

5K views 18 replies 10 participants last post by  ch.1953 
#1 ·









Let me just say that removing the manifold to replace some measly spark plug wires is a major PITA.

Took me at least 3 and half hours to remove it.

Second, looks like I'm screwed. The car needs a body harness as you can see. Whoever tried to do a cheap fix by splicing the degraded wires and replace the MAF connectors clearly neglected the rest of the wires.

The upper harness was replaced in 2005 but amazingly the dealership never bothered with the body harness. Happy Birthday to me.

The car is not showing errors in the cluster, runs smooth but I've read horror stories on cars running on bad harnesses so the car will be out of commission until the part gets replaced.

Three things:

1. I need a part number for the Delphi Body Harness and how much is it?

2. How many labor hours are we looking here for removing and installation?

3. Anyone have a diagram or diagrams of the body harness and where its suppose to connect to?
 
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#2 ·
#3 ·
Sad to hear that man. I hope you can get it fixed. I did an inspection on mine and the coating on the wires look like yours, but mine have some of the coating gone and just bare wire. I don't drive my car much at all. This year I prob have put less than 600 miles on my car. I bought it as a collectors item. Although it may never be that, but it is nice, clean and fun to drive whenever I do take it out.
 
#4 ·
You're a brave man to continue driving in such conditions!

Is the car showing any symptoms with the rotten wires on yours? If you've driven it 600 miles then it must be running miraculously eh?
 
#6 ·
Well as I mentioned, I don't drive the car alot. For one gas prices are high, that engine is very thirsty, and I have other vehicles. I use to take it out if I am going out to a dinner or just to take it for a spin. As far as symptoms go, I have only noticed the regular things like the Headlight switch needs replacing as it doesn't stay pulled out when turning on fog lights. My Hydraulics shocks do not work. I have drove the car out of town about 1600 miles or so and that was the longest trip.
 
#5 ·
Be warned! You run the risk of blowing your motor if the old harnesses are not replaced with the new (non-soybean) wiring.

I know.

That's how I came to get my 600SEL for FREE, because someone continued to drive it without the body harness replaced. It's original engine blew because of the shorts. I found a used engine and a used (non-soybean)harness and was able to put it together.

But you are running great risk trying to fix what I would consider unfixable. The connections are the complication in re-habbing an existing harness.

Try to find a used one, like I did, or save up for a new one and get OEM. It's your only assurance of a job done right.
 
#7 ·
Are not all of the wires under the hood considered part of the engine wiring harness?

I am wondering what all the "body" wiring harness wiring consists of.
 
#8 ·
There are two main harnesses to the car, the engine (or upper) harness and the body (or lower) harness. Both got the soybean treatment in the early 1990's by MB, in a move to show how environmentally conscious they were.

The engine harness is the simpler of the two and is all in the engine compartment.

The body harness runs from the computer boxes (aka mouse coffins) throughout the car, connecting all the electrical components.

The components themselves, manufactured by outside contractors, do not have that soybean wiring so they will not fail like the harnesses do.
 
#9 ·
the body harness is also incharge of the o2 sensors. on my 97 its not soybean but the exhaust shop ruined my wires by tugging on it :( eddie is going to send me that section only and i have to repair it. it costs about $5,500 for the 96-99 body harness from the dealer. since my harness is only damaged in that location i am going to replace only that part and solder it and then coat the wire and then shrink wrap and last but not least heat wrap.

but if i ever could afford new harnesses i would replace them. on mine there is really no need except the clips that attach to the individual coils are missing the clip part of it(dealer replaced plugs and coils i guess they were just dried up when they touched it) i know somebody that had a 98 s500 and had his body harness replaced and it cost about $10k with labor but that car is now fully restored he bought the car off someone who tried to bypass alot of the stuff and add speakers and other stuff. and they ruined a perfectly good harness
 
#10 ·
New body harness? Try this first !



This is my experience, I want to share with you and all members of the Forum: recently I bought a 1990 W124 sedan model 300E. I dind´t know the car. I cheked many systems, almost all very well, but the tranny that haven´t received a change of fluid since who knows when.

I begun to experiment a series of electric troubles. For instance, windshield wiper started when I turned light beam on. I decided to check the fuses, the relays. I cleaned them with contact cleaner. Guess what: some electric problems dissapear, new electric problems started: windows didn´t close with the car in march, but operated well with the door open ¡¡¡¡¡????.

I put on my glasses and looked the fuses with more detail: they where worn in the extremes, so making bad contacts. I changed 4 of them with the spares and voila! problems connected to that fuses dissapear.

I am going to change all the fuses on monday.

Try the simple first, maybe your harness is ok.

OldBeaver
 
#11 ·
OldBeaver:

Do NOT mislead yourself or anyone else: The photographic evidence is classic harness failure, where you see cracking and missing wire insulation, you run the risk of shorts, fires, blown motors, etc. In short, leaving that situation unaddressed will (not may) lead to disaster of the most spectacular kind.

The photos show not a 'maybe' the wiring harness(es) are failing, they are showing FAILED wire harness(es).

As good as your intentions are, and as sound as your advice may be, to check the simple things first, the original poster's photographs show a problem that needs to be addressed.
 
#12 ·
Stryker is right, if anyones harness is looking like that it is TIME to CHANGE it. Mine is probably worse than the pictures are showing. I called the dealer today to find out how much the engine harness was and they quoted me about $700 + on the lower end. (discount given) If you really like the car, get the harness replaced. If money is tight I do understand, just be careful. Mine is parked of course I have other transportation.
 
#13 · (Edited)
Dont mean to hi-jack vaevictisasmadi's thread, but I have a quick question concerning mine.

I know that the engine harness was replaced on my '93 W140 in 2001 to the tune of around $775. I am not sure about the other harness, or even where to look for the wires to check. When I pop the hood on my W140, I only see very few wires that I can actually see and they look fine, but they may be part of the engine harness that have already been replaced. The car has been garaged since new and well serviced and only serviced by MB techs since new. I am sure that the shop that has serviced this car for the last 6 years would have mentioned to the owner any problems, but you never know. I dont have any issues, not yet anyway, but would like to know if the problem has been addressed or if it may soon be an issue. There are so many service records to look through, I havent had a chance to look through them all.

Here are the only wires I can see on my car just by opening the hood... are these part of the engine harness or body harness and would these be the first to crackle? Is there a panel that is best to remove to inspect? These look OK to me...



 
#14 ·
A bit of an update.

After much procrastination from my mechanic friend, his auto electrician friend finally finished rewiring my body harness. He only worked on the car during his spare time so it took awhile.

The wires were so bad that they had to remove the computer box and start rewiring from there. Under the computer box, the wires were NOT degraded, so the heat didnt do its damage in that area.

While I was at the electricians shop, he had other cars in there with wiring problems worse than my car. One was a first gen Lexus IS that had bad wiring all over the engine bay, and even worse, the problems continue inside the car, having to remove the dashboard completely, as well as the center console. The amount of wires needed to be replaced was simply ridiculous that the electrician simply laughed at "my wiring problems" and said "compared to modern cars with all the wires that they have, yours look like a piece of cake".

You hear that people? your much dreaded 600 wiring problems are nothing but a small fish in a big pond now compared to modern vehicles. Which makes all the more hilarious when people here spread FUD at how rewiring a 600 is like rewiring a Space Shuttle. Please.... :rolleyes:

Total cost of parts and labor for the rewire was.... lets just say its under a grand :thumbsup:

The car is still a long way to go from what I would consider "restored", but its biggest achilles heel is finally fixed and everything else seems peanuts in comparison.

As a souvenir, the electrician gave me some of the old MAF wiring:


You can see where the previous owner/mechanic(?) tried splicing the degraded harness with new wires, which didnt work out as planned. The electrician mentioned this bundle is only a small portion of the total amount of wires he replaced, which if you look at my original post in this thread, rings true.

Upon startup, the idle is smooth as silk and quiet like a motor turned off, which was a far cry from how it used to run prior to fixing the harness. I didnt get a chance to drive the car, but I did let it run for a good 5 minutes while testing out certain things and I was left impressed.

Its a bit of a heartbreaking moment knowing I cant drive the car for another couple of months while it undergoes restoration. That V12 is quite the potent drug I tell ya :D
 
#18 ·
The wires were so bad that they had to remove the computer box and start rewiring from there. Under the computer box, the wires were NOT degraded, so the heat didn't do its damage in that area.

Total cost of parts and labor for the rewire was.... lets just say its under a grand :thumbsup:
As others wrote, do NOT delay having the w/h replaced (or rebuilt) b/c I seen many ECUs bite-the-dust b/c of shorted wires in the cable harness.

Tnx for posting the great pictures of the failed w/h. As we all know, a picture is worth a thousand words and your pics show the crumbling wires very clearly. :)
 
#15 ·
How well I know the kind of drug the V12 is!

Meanwhile, not wishing to cast doubts or otherwise be a downer, but repairs such as yours are prone to failure, for no reason other than you left some of that dreaded soy-based insulation on the wires. That material is literally rat-food, not just subject to dry-rot as you can see. Just beware of the unstable condition of the repair, not because you/your mechanic didn't do a good job, but because it is not a comprehensive one.

Otherwise, good luck!
 
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