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Back at it again-- 95 s600 Coupe

3K views 21 replies 7 participants last post by  Steve_B 
#1 ·
Hello again guys!!

I'm back with a 1995 s600 coupe. If you remember, I had a 98 s600 coupe that got vandalized to the point that I decided not to spend the time and money to bring it back.

I just bought a 50,000 mile s600 coupe from California. I know it needs cats. I still have the 98 and wanted to know if anyone can tell me if they are the same. I could take them out of the 98 and use them in the 95. Anyone know for sure?

I also have 2 codes in the LH. Code 4 in both which leads me to believe that there is a fault in the harness for MAF.
It also has a code 10 in the LH1

Any thoughts/advise is GREATLY appreciated.

Thank you in advance.
 
#3 · (Edited)
Congrats on the new purchase.
How do you know it needs cats (with only 50K on the clock)?

I am not familiar with the '98, but it should have two sets of O2-sensors, upstream and downstream. The '95 should have only one set, upstream of the converters.

You probably can use the '98, if need them indeed, and have to just plug the holes.

Steve
 
#4 ·
I agree with Steve. Cats at only 50K? Sounds like you need to put it on a computer and get all of the codes. And I can't imagine even needing O2 sensors at that mileage.
I bought a '97 Cl 600 with only 46K and those components weren't even discussed. However, I did have a bad MAF.
Anziani
 
#5 ·
I agree guys. VERY low miles for Cat failure... But.... It is obvious that they are bad. Passenger side for sure. The flame retardant coating on the pipe is gone, and the rear bumper is actually melted about 2 inches above the tail pipes. When it was delivered to me in Atlanta was the first time I saw it run. It ran "fairly" smooth. The v12 should be as smooth as glass. It wasn't. I pulled codes and found code 4 in both left and right ecu's. Also found code 10 for the left side.

I have looked at a small section of the harness and see some cracks. My thoughts are that there is a short somewhere in the harness.

I cleared the codes and ran the engine at idle, revved it a few times and I can hear the exhaust is plugged.

Anyone have any ideas?
 
#6 · (Edited)
I agree guys. VERY low miles for Cat failure... But.... It is obvious that they are bad. Passenger side for sure. The flame retardant coating on the pipe is gone, and the rear bumper is actually melted about 2 inches above the tail pipes. When it was delivered to me in Atlanta was the first time I saw it run. It ran "fairly" smooth. The v12 should be as smooth as glass. It wasn't. I pulled codes and found code 4 in both left and right ecu's. Also found code 10 for the left side.

I have looked at a small section of the harness and see some cracks. My thoughts are that there is a short somewhere in the harness.

I cleared the codes and ran the engine at idle, revved it a few times and I can hear the exhaust is plugged.

Anyone have any ideas?
I am lost. How do you know the pass-side is plugged up? You have dual exhaust? Can you post pictures of what is melted?

If I were you, I'd remove both oxygen sensor and start it from cold. Feel the exhaust stream from the two holes. The O2-sensors are just before the cats.



If one is flowing better than the other, the pressure there will be lower, you can feel the difference.

If flow is equal, again, I don't think you can expect melted cats at this mileage. Unless, of course, the car has been severely neglected and run with damaged MAFs of injector harness.

Post some pictures, please.

Good luck,
Steve
 
#7 ·
Steve,
I see how all this can be confusing. Let me start from square one.

I bought the car and had it shipped to Atlanta from San Francisco. When it got here was the first time I saw/heard it run. It started and had a check engine light/ASR and ABS lights.

I grabbed a scanner and pulled MAF codes. I put the car in the air to look at the undercarriage. Clean, no leaks or damage. When looking at the exhaust, the heat shield on the passenger side exhaust (at the cats) is flaked off. Also, the rear bumper right above the tailpipes is melted (badly) the absorber which is the Styrofoam piece under the plastic bumper cover is also melted. This tells me that the exhaust got ridiculously hot. I am positive it had to do with the MAF codes.

The car ran fairly smooth, not as smooth as being on 12 cylinders. So.... I know something is wrong. I cleared the codes and let the car run for about 20 minutes at idle. I then tried driving it in the parking lot. It runs better, but you hear back pressure in a major way when accelerating. I got the car back in the air and used a laser thermometer and the passenger side cat was flaming hot. Don't remember the temps right now. So.... I am virtually positive the cat is shot. I cleared the codes, they have not yet come back. I hope that clears things up. I think the problem is in the wiring. Any thoughts guys?
 
#8 · (Edited)
Steve,
I see how all this can be confusing. Let me start from square one.

I bought the car and had it shipped to Atlanta from San Francisco. When it got here was the first time I saw/heard it run. It started and had a check engine light/ASR and ABS lights.

I grabbed a scanner and pulled MAF codes. I put the car in the air to look at the undercarriage. Clean, no leaks or damage. When looking at the exhaust, the heat shield on the passenger side exhaust (at the cats) is flaked off. Also, the rear bumper right above the tailpipes is melted (badly) the absorber which is the Styrofoam piece under the plastic bumper cover is also melted. This tells me that the exhaust got ridiculously hot. I am positive it had to do with the MAF codes.

The car ran fairly smooth, not as smooth as being on 12 cylinders. So.... I know something is wrong. I cleared the codes and let the car run for about 20 minutes at idle. I then tried driving it in the parking lot. It runs better, but you hear back pressure in a major way when accelerating. I got the car back in the air and used a laser thermometer and the passenger side cat was flaming hot. Don't remember the temps right now. So.... I am virtually positive the cat is shot. I cleared the codes, they have not yet come back. I hope that clears things up. I think the problem is in the wiring. Any thoughts guys?
How hot is HOT? Cats operate at around 600 degrees (inside) and you should be measuring something like 300-400 with an IR thermometer on the outside.
Cat. converter that is hot is working!

As far as exhaust being able to melt the bumper -- I am not convinced this is possible. If this is indeed the case, all rubber hooks (all 4) that support the rear part of the exhaust will be burned to ashes.

You are onto something by saying that it is your wiring though. One bank is running rich(er).

Steve
 
#10 ·
Ok Guys..... So.... The fun continues.
I removed and gutted the cats..... passenger side was COMPLETELY clogged. Car runs much better now. Still need to chase wiring for MAF is my guess.

In the meanwhile.... I am having a ton of other electrical gremlins which seem to confirm harness issue.
The AC control panel will not work at times. The fan comes on and stays on. When I try the headlights, the fan speed increases when the car is running. From there, I turned the key off, removed fuse 18 and then went back in the car, turned the key back on and was able to get the hvac panel to activate normally when I turned the key back on.

I went ahead and reinstalled fuse 18, which made the fan start running again and made the hvac panel go back to dead.

I "think" my problem is in the main body mounted harness. I was able to source one on ebay. I will be tackling the replacement myself. HAs anyone done one before? What do all these connectors go to?

Anyone have any thoughts on where else I should look? Any wiring diagram gurus available to look at correlation on fuse 18 with headlights? I have looked and cant quite figure it out.

Please guys..... The strength and combination of smart people will lead to a solution.

I'm new to this and could really use some help.
 
#11 · (Edited)
I "think" my problem is in the main body mounted harness. I was able to source one on ebay. I will be tackling the replacement myself. HAs anyone done one before? What do all these connectors go to?
This must be ONE OF THE WORST jobs one can do on a w140



Very unusual! More common problems are with the MAF wiring and especially the fuel-injection harness.

Good luck,
Steve
 
#12 ·
Guys,
It looks like I am embarking on the body harness replacement...... The Maf connectors are part of that harness.....

I can not find one for a 95 s600. They are no longer available from Mercedes. So.... I found one on ebay. New in the wrapper. It was made in 2006. The only problem is that it is for a 93-94 600sel. The part number is 140-540-48-05.

Can anyone tell me what would be different about this harness? I have not taken mine apart yet. But, I did buy the harness on ebay. It's on its way to me.

Maybe someone can help shed some light?
 
#14 · (Edited)
We were talking about this not to long ago... On this thread-post16 on forward....

http://www.benzworld.org/forums/w140-s-class/2792362-joes-600sel.html

My post 33 has all the links to the actual Mercedes instructions for the repair. I have a friend that actually has about six pairs of these connector heads too...

I have done the job. Each MAF has five wires, and one of those wires gets terminated to a ground-ring terminal near the big engine connector. The other four go to one of the engine computers-Per the instructions one is asked to put a hole in the plastic portion of the coffin box, and silicone the hole with the wires. The same is done for the other MAF, and that goes to the other engine computer...

Ahhh, one more:

http://www.benzworld.org/forums/w140-s-class/2645738-600sl-engine-wiring-harness-600sel.html

All the best

Martin
 
#15 ·
Believe me guys, The last thing I want to do is to replace that entire harness. The problem is that there are wires that are damaged near the coffin box too. It's not just the MAF sensor wires. It might serve to just do the whole harness.

This car has a list of problems that seem to be wiring related.

The radio stays on even with the key off and out.
The climate control will work sometimes, other times will not. When it does work, it sounds like there is a restriction causing the air to go straight to defrost. Like I said, at times it works perfectly.
The ABS and ASR lights stay on. I have replaced the brake light switch to no avail. Scanned and has no codes.
The check engine light was on with code 4 in both left and right LH modules. Also had code 10 in Right LH module.
The MAF readings are 2500 and injector pulse was at 43.

It all seems to lead to wiring. I looked at Victors youtube channel. He had a video on his 95 S600 Coupe that is exactly what has happened to mine. The coffin box drain was clogged, mine was too. It appears to have added to the crumbling wiring issue.

I really don't WANT to replace the harness. Maybe I will splice in the parts that I can see are bad.

Any thoughts on the issues I posted that might keep me from pulling what's left of my hair out?

Steve and Marvin,

THANK YOU!!

The entire team here is great. I will keep you all posted. This is going to be a long process.

Please send your thoughts/suggestions/replies.
 
#17 · (Edited)
Believe me guys, The last thing I want to do is to replace that entire harness. The problem is that there are wires that are damaged near the coffin box too. It's not just the MAF sensor wires. It might serve to just do the whole harness.

This car has a list of problems that seem to be wiring related.

The radio stays on even with the key off and out.
The climate control will work sometimes, other times will not. When it does work, it sounds like there is a restriction causing the air to go straight to defrost. Like I said, at times it works perfectly.
The ABS and ASR lights stay on. I have replaced the brake light switch to no avail. Scanned and has no codes.
The check engine light was on with code 4 in both left and right LH modules. Also had code 10 in Right LH module.
The MAF readings are 2500 and injector pulse was at 43.

It all seems to lead to wiring. I looked at Victors youtube channel. He had a video on his 95 S600 Coupe that is exactly what has happened to mine. The coffin box drain was clogged, mine was too. It appears to have added to the crumbling wiring issue.

I really don't WANT to replace the harness. Maybe I will splice in the parts that I can see are bad.

Any thoughts on the issues I posted that might keep me from pulling what's left of my hair out?

Steve and Marvin,

THANK YOU!!

The entire team here is great. I will keep you all posted. This is going to be a long process.

Please send your thoughts/suggestions/replies.
I suppose I am missing something here. If the ECU's suffered some damage from moisture, why do you think the replacing the main harness will solver the problem?

I did the MAF rewiring myself, and other than the problems putting the box back together and fitting the cooling duct

http://www.benzworld.org/forums/w140-s-class/2620993-ecu-cooling-module-box-ventilation.html

there were no major issues. I am not good with the soldering gun and was not feeling too comfy in that crowded space, but must say that the project is not difficult. If you were closer, I'd offer to do it for you free (if you supply the beer).

Steve
 
#16 ·
I have a vague recollection that it's a $3k+ part, when available, and 30+ hours of professional labor. On the bright that suggests that it can be done but I don't think many people have done it. I've heard about a lot of patching over the years. It seems that only 600s have a biodegradable engine harness / body mounted.
 
#18 · (Edited)
I have a vague recollection that it's a $3k+ part, when available, and 30+ hours of professional labor. On the bright that suggests that it can be done but I don't think many people have done it.
There have been epic battles on this subject that one can find in the archives, and I think everyone can form an educated opinion.
As an (current) owner of car that should be prone to those maladies, and having found none, I may speculate that very few other owners have done it, probably because people have realized that it is not necessary.

The dozen or so bad wires can be replaced in one afternoon by a rookie, Martin probably can do 2 or 3.

I've heard about a lot of patching over the years. It seems that only 600s have a biodegradable engine harness / body mounted.
I have not only heard about it -- I've actually repaired it by myself.

And, something that we also discussed not too long ago -- the 600SEC I have been working on for the past 2.1 years has NO "biodegradable" harness.

It did have wiring that needed replacement, but not because bacteria ate the yummy plastic...

Best regards,
Steve
 
#20 ·
Ok Team!

I went ahead and performed a thorough inspection of the harnesses. The injector harness is in good condition. All of the major problems with the care are related to the main body mounted harness. The wiring is cracked and bare wires throughout. I would much rather replace the entire harness than repair the one I have. It is not just the MAF wires. The A/C is affected, cooling fans, the list goes on and on. This is a 50,000 mile car. If I'm going to do it..... I want it right. I have reached out to the Mercedes Classic center in California. They do NOT have any of the harnesses available. I wanted to replace the 3 main harnesses, the body mounted, injector and the starter/battery harnesses. No luck on any of them. In the US and in Germany.

Does anyone have these harnesses available from maybe a parted car? I will buy all of them. Any other suggestions guys?

I am not willing to let this car die. I will be removing the throttle actuators and sending them to be rebuilt also. Any recommendations?

Thanks.
 
#21 ·
Ok Team!!

Hers is the update!! I have taken the car apart to inspect all the harnesses. The injector harness is ok. A few cracks, but nothing major...The main harness is completely done. I have reached out to the Mercedes Classic Center in Cali. No harnesses available for this year. Mine is a 95 S600. I would like to replace them with new ones. but....NLA....

The car deserves to be made right. I would like to replace the injector, main body mounted harness and the starter/alternator harnesses.

Does anyone have these in a car that they are parting out? Would have to have been replaced at some point with updated wiring though.... I am willing to pay a fair price for them. I am also planning on sending the throttle actuators out for rebuild. Any suggestions on the best?

Any suggestions on the harnesses? I would rather replace than repair. If there are no other options.... Any suggestions for the repair? Not something I would want to do myself.

The problem with the body harness is that it's affecting other systems as well. It's harming the A/C system, cooling fans, ASR, Etc...

Please offer any and all help. I REFUSE to give up on this sub 50k mile beauty!!

That's why I'm asking the ENTIRE team here for help!

Thank you!!
 
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