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1995 S600 (sold)
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Discussion Starter #1
Well, I decided to take a closer look at all the wires under the hood of the old V12 this weekend. I had pulled off the passenger side cover to check on something, and noticed small cracks in some of the wires. Closer examination showed five wires cracking along their entire length. These wires connect to the passenger side throttle actuator. Carefully cutting the sleeving away revealed badly cracked insulation. Very scary. I cut off the passenger side throttle connector, and working very carefully with a razor blade, I was able to pry the connector halves apart. The point where all the wires bundle tightly into the connector was really bad. I'm going to patch this up temporarily with new teflon insulated wire until I can figure out which harness p/n this is. It's not the harness for the injectors, that one looks brand new. It's odd, it's only these five wires that look bad. I'm certain the drivers side is the same, so that'll be next. Take a look at the pics...
 

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SEC 600 V12 2dr COUPE (RHD) One of the chosen few.
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When I had my trouble with my harness I found that all the wires had a joint between the big multi plug and the place they where going to.. If you remove that part of the loom/harness, you might be able to replace each individual.. However I did not make this discovery till I had bought the replacement.. Find out how much the stealers want for the harness .. then I can tell you if they are cheaper over here.. Wow that looks bad in the last pic.. TROUBLE IN STORE..
 

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1995 S600 (sold)
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Discussion Starter #3
I asked my parts guy to quote this particular wire harness. He came back with $550.00. It turns out the harness he quoted includes the wires for the injectors. The injector wires on my car look brand new, and the bundle still has the part number he told me I needed on it. Someone changed this harness in the past. That harness however does NOT include the wires to the throttle actuators. I gave him the part numbers from the connector at the end of this harness, and he said that part shows as not being used on my car! Geez. Nothing is simple. Fortunately, I work for an aerospace company, and I have access to all sorts of wonderful stuff, including teflon insulated wire good to 200 degrees C. I'm going to change the wires out individually as you suggested Merc.
 

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1995 S600 (sold)
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Discussion Starter #4
I looked at the driver side wires tonight. Not as bad as the passenger side, but also cracked. Again it's only the five wires going to the throttle actuator. Someone in the past tried a poor fix on the wires near the connector. They injected some sort of rubber / insulator in an attempt to fill cracks in the insulation. I cut the connector off, and was able to pry that one open too. I'm changing all the wires to teflon insulated ones. The good news is that the cracking in all the wires stops before the bundle heads down under the module box. I'll simply splice new wires up to good lengths of old wire. It looks like a mess right now, but it will come together nicely. Let's see, where did that one wire go?
 

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This is not a throttle actuator harness. This is a Air Mass Meter harness and it is available from MB as a repair kit for about $100
 

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1995 S600 (sold)
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Discussion Starter #6
That makes perfect sense myarmar. Thanks for waking me up [:)]. I don't know why I thought this was the throttle actuator. In any case, I was able to repair the harnesses with new wire. See attached pics...
 

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Discussion Starter #8
Thanks for the compliment myarmar. Luckily I didn't have to replace the entire wire length. The wires look OK once they approach the module housing. It looks like the wire survives intact once it's away from the direct heat of the engine. I'm going to splice the new wires onto the old using MIL-SPEC heat shrink tubing with built-in solder, and water tight adhesive. The insulation on the new wire is good to 200 degrees C. If it ever gets that hot under the hood, the wiring will be the least of my worries.
 

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1995 S600 (sold)
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Discussion Starter #9
I spliced my new home-made harnesses in last night. It went well. I feel very good about getting that old wire out of the car. When I was checking the pin outs of the connectors, I saw some continuity between wires. VERY BAD! Now, that could be because the insulation came off when I pulled the connectors out of the car. But the way those wires looked, I wouldn't be surprised if there was a little cross-talk going on. Driving to work this morning, I swear the car idled better than ever. It's probably my imagination, but so what[:)]. I'll create a gallery to load all my pictures for my Forum friends in case they ever need to do this themselves.
 

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SEC 600 V12 2dr COUPE (RHD) One of the chosen few.
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Will you supply specs of the wire .. so we can get some ourself
or get it from you..
 

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1995 S600 (sold)
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Discussion Starter #11
The wire I used is MIL-W-22759/34, 18 gauge. The insulation is teflon, and the wire is rated to 200 degrees C ambient, and can withstand a max conductor temperature of 150 degrees C.

If demand is not too high, I may be able to supply wire for you.
 

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speaking as an ex-military avionics technician - thats a TOP piece of wiring !Will do mine if it ever goes again.[:)]
 

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Discussion Starter #14
Okay, now I'm wondering about wires for the throttle actuators. I'd like to check those wires for cracked insulation. I'm having a difficult time seeing a connector on these. It's probably buried under something. Anybody have any experience with these things?
 

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Pas. side ETA connector is visible on your picture:
http://mbnz.org/gallery/pics/13_1425364_312005114517PM.JPG
It is between coolant tank and a fender. Read this:
http://www.mercedesshop.com/shopforum/showthread.php3?t=112493
 

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1995 S600 (sold)
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Discussion Starter #16
The connector for the TA is what I circled in the attachment?

What a coincidence, I found that same thread last night! I read every posting. I'm very concerned that the wires are shot. I'll be digging in there in the near future. I'm treading on thin ice though, I've been out in the garage a lot lately, and the mrs. is getting antsy[:)]
 

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Discussion Starter #17
I just can't stop myself. As you probably guessed, I was worried about the condition of the wire in the Throttle Actuators (TA). Seeing what the wire looked like in the MAF's, I strongly suspected cracked insulation in the TA's harnesses. I took the passenger side TA off, and pulled it apart. Guess what? Insulation cracked. Plus I'm disappointed in MB's solder quality. There is some corrosion on the circuit board. Probably from poor cleaning after initial soldering. I will touch that up as well. The inside of the assembly looks like it's in very good condition. I will give it a good cleaning, and leave it as is. I was able to get the connector apart on this harness, and I'll be able to use it again. I'm going to try and find even better insulation material for these wires, because they are very close to the exhaust manifold. Tonight I'll pull the driver's side TA. This one is a little more complicated, since it's the one with all the cable attachments. Once I'm done with this project, I'll post pics in a gallery for your viewing enjoyment. All kidding aside, this is something that everyone should consider. A short circuit in this assembly could mean big money in repairs. By the way, does anyone have a good schematic of the wiring for both TA's?
 

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That is so typical MB trying to cut corners..Now I am scared to death about what I might find If I take mine apart.. more sleepless nights then...Is the section replaceable..
 

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1995 S600 (sold)
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Discussion Starter #19
No, the section is not replaceable. You must cut off the wires from the circuit board within the actuator. Also, the wire sheathing is attached to the actuator housing using a type of retaining device that cannot be pulled out of the actuator housing without really butchering it up. The wires are not easily pulled out of the sheathing / tubing. I cut the bundle section in half (between the actuator and connector), and tried pulling the wires out of the sheathing after I cut the wire ends from the board. They didn't budge. The wires have a slight helix to them within the sheathing which makes it difficult to pull the wires out. In addition, there are four or five dummy wires made of black plastic with the wires. These are not conductors. I believe they are there purely to create a tight pack within the sheathing, and this is what makes it hard to pull the sheathing off. I left the attachment point of the sheathing intact, along with a short section of the sheathing. I will re-use this, and attach new sheathing to it. I'll use new wires, sheathing, and re-use the connector. I'll take some pics once it's done and share with you.
 

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1995 S320 LWB W140
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61 Posts
the wiring harness should be fully replaced at about this time. The one benz put on was cheap and isn't good with heat, which is usually prevalent alot around an engine, go figure. the best thing to do is get the entire wiring harness replaced, the part was if i remember correctly about $1500, we need to do that on ours as soon as some money free's up.
 
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