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Hello, I'm Larry, a newcomer to the forum, I currently own a 1995 SL 320, saw a Youtube video about the self destructing wire covering on models between 1990 and 96, I believe, Well 12 yrs after my purchase, I noticed wiring everywhere crumbling. I'm looking for a replacement harness, used if available and I guess I'd pay the tariff for a new one if I can't find a good used one. Anyway, I ran some new wires to the new coil packs I installed, actually in the process right now. I can't find any answers on Youtube or Google as to which is negative ground and the power side. My coil harness is just destroyed and can't tell many of the wires. Anyone have a clue on this one, I certainly would appreciate it, thanks all, slpell
 

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93 SL500, 95 SL320, 96 S320, 98 S500, 2002 E320 4Matic Wagon & A little 91 5.0 FORD Mustang
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Welcome to the forum Larry, and thank you for your post...

The easy way out to be rolling fast, and cheaply is to go to the self-serve junk yards where you can find a W140 S320 from 1992-1996, yet you may luck out to find a SL320, but the ratio to every SL you find. You will find 30 to 50 S320's The difference in the SL320 to the S320 is the S320 is about one foot longer, and has no rubber bulk-head square grommet. A revised S320/ SL320 harness has a white Delphi tag near the big rectangular disconnect. The junk yard harness will probably cost you under $20 to $30 USD, but you need to go searching for it YOUR SELF...

Here are a few of the biggest junk yard chains:


You could get it from the parts pullers, but you may pay a few hundred for it, yet just advise them that you want the harness with the white Delphi tag at the big rectangular connector.

Look at this link:


The ground on these harnesses is a stud on the chassis. The ground wire has a ring terminal, and other grounds will be there on that stud too.

Remember, the lower harness is probably in the same shape, and you may have to hand wire that one as it is five or six wires, but that lower harness does the starter coil, oil sending wire(s), alternator wires and the large charging wire, but that large wire does not get damage.

Here are the Schematics from this site-Look at the Legend and Diagnostic tabs


Here is how I decode them


How to read them:


Something that may help:


Someone decoded the W140 diagrams to PDF.


That should get you rolling..

Martin
 

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1994 SL500
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Hello, I'm Larry, a newcomer to the forum, I currently own a 1995 SL 320, saw a Youtube video about the self destructing wire covering on models between 1990 and 96, I believe, Well 12 yrs after my purchase, I noticed wiring everywhere crumbling. I'm looking for a replacement harness, used if available and I guess I'd pay the tariff for a new one if I can't find a good used one. Anyway, I ran some new wires to the new coil packs I installed, actually in the process right now. I can't find any answers on Youtube or Google as to which is negative ground and the power side. My coil harness is just destroyed and can't tell many of the wires. Anyone have a clue on this one, I certainly would appreciate it, thanks all, slpell
There are 2 harness to deal with. 1 is the fuel injection harness that others on this thread are talking about. there is a 2nd 3 wire harness that runs from the ECU to several sensors on the left side of the engine. Search my threads for detail on replacing/rebuilding the 2nd. let me know if you cant find it and i will repost.
 

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1993 500SL
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SL's & 500E's
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I am not familiar with M104 SL's, but as a general observation concerning other wire harnesses that "may" need to be replaced as well; on the 3 W124's I own that came with the bio-wires, the following had to be changed;
  1. Upper Harness - Fuel injection
  2. Lower Harness - Starter
  3. ETA, (Throttle Body), harness - (not replaceable), Throttle Body taken apart and rewired by hand
Not sure how this translates to a R129 M104 specifically, but in general the lower harness, (starter to alternator etc.), and the ETA were always effected as well. Also appears that member "jsargent99" is discussing the same topic and has a handle on another cable set, (or maybe thats the starter harness he's referring too). Long story short, there is more to replace that just the upper wire harness.
 

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1994 SL500 1998 SL600
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I can confirm the ETA harness is the worse. Before replacing everything else I suggest to split open that harness and check the condition of the wires.
 

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SL's & 500E's
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Here is a very reliable business to rewire your ETA


find the phone # on the website, and call Victor, he has worked extensively on my 500E's and knows exactly what you need....

Not only just rewire, he will rebuild the ETA if needed, a full checkup... he also rebuilds wire harnesses..

He has a ton of videos on YouTube, check them out, search for restoreyourmercedes on utube...

Good Luck
 

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1994 SL500
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11 Posts
I am not familiar with M104 SL's, but as a general observation concerning other wire harnesses that "may" need to be replaced as well; on the 3 W124's I own that came with the bio-wires, the following had to be changed;
  1. Upper Harness - Fuel injection
  2. Lower Harness - Starter
  3. ETA, (Throttle Body), harness - (not replaceable), Throttle Body taken apart and rewired by hand
Not sure how this translates to a R129 M104 specifically, but in general the lower harness, (starter to alternator etc.), and the ETA were always effected as well. Also appears that member "jsargent99" is discussing the same topic and has a handle on another cable set, (or maybe thats the starter harness he's referring too). Long story short, there is more to replace that just the upper wire harness.
[/QUOT

No I was referring to the lower harness aka stater harness aka alternator harness aka lower engine harness. My earlier post on the topic has disappeared. However what I wanted to point out about the lower harness is that although there is a wire that runs back to the starter in the harness bundle, the starter wire, at least on mine, was not made out of the biodegradable wire. Therefore that wire did not need to be replaced. This means that YOUR DO NOT HAVE TO REMOVE THE STARTED which is a major pain in the ass. So before you follow the instructions in other posts on this forum that start with remove the starter, do yourself a favor and open up your harness and see if starter wire (mine was white with a purple stripe) is degraded or not. If not just replace the others.
 
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