The engine wiring harness suffers from a cracked insulation in several places, including connections to the ECU. You're better off replacing the darn thing.

Sergio

 

The engine wiring harness suffers from a cracked insulation in several places, including connections to the ECU. You're better off replacing the darn thing.

Sergio

Note: This guide is intended for those who don't want to or who don't have the cash for replacing the harness at a cost of $800-$1500 for the part alone. Although replacing the harness is best, it's not always a feasible option.

 

But you run the risk of damaging the ECU and other electrical components.

Sergio

 

Repairing the harness in the way I described won't put your ECU at risk. In fact, you're more likely to protect your ECU by performing this repair, rather than just leaving it broken (with the wires shorted out and the cylinders misfiring).

 

I just changed the wirring harness for my c220, but the car still displays the same kind of rough idle it had before. I thought this would fix it. What else could it be?

 

Check your motor mounts..

 

I just changed the wirring harness for my c220, but the car still displays the same kind of rough idle it had before. I thought this would fix it. What else could it be?

Your MAF sensor may be bad. There's a couple recent threads in this forum about how to replace it.

 

I don't mean that doing this repair could damage the ECU; what I mean is that leaving the bad engine harness in place could damage the ECU so even if you perform this repair, there are other areas of the harness which still have problems so the best bet is to replace the entire harness.

Sergio

 

Wiring Harness

I just got a quote to replace my harness for 1508.00 from a MB dealer here in the Toronto area... I think I am having the same problem...Sometimes the engine runs real smooth and at other times seems like it is missing on a couple of cylinders and has absolutely no power... Does this sound like the same problem to you and if so can an average guy (pretty mechanical) take this apart and fix it..

Pete

 

harness

I just got a quote to replace my harness for 1508.00 from a MB dealer here in the Toronto area... I think I am having the same problem...Sometimes the engine runs real smooth and at other times seems like it is missing on a couple of cylinders and has absolutely no power... Does this sound like the same problem to you and if so can an average guy (pretty mechanical) take this apart and fix it..

Pete

if the problem continues, you can check your plug wires for licks. i have encountered similar problems until one of the plug wires was replaced.

 

It is possible, as demonstrated by my photos, to repair the harness without replacing it. Unfortunately most dealerships are no longer offering "goodwill repairs" on the C-Class engine harness, so a temporary repair as per my instructions will work.

 

Cost of harness here (Thailand) around $400. It is local made but work great.

 

Hey, can I buy one from Thailand?? Let me know via my email: sygon@live.com

 

I spent a week trying to find a decent harness for my 95 C280 but ended up buying a new one from a MB dealership several months ago. I am in Houston Texas and it cost about a grand for the harness. I was told by the MB dealership where I bought the harness that these cars came off the line with defective wireing harness' and many MB dealerships did replace them at no charge for several years. I just waited too long. I also had a ton of other work done at the same time. Fuel filter, plugs and wires, tune-up, belts, etc. All in all it came to $2300. I hope it was worth it. The car is cherry as far as looks go. I just bought a fan clutch off eBay for $99 because I know that will go out next according to my mechanic and I noticed just as he said, the temp now runs at 100f instead of the 80f I am used to seeing. Strangly, I was getting 31MPG on the highway (air off) before the tune-up but now get only 29MPG. Go figure.

 

Hi, I would like to point out that waether you can afford it or not one must replace the whole harness once it gets to that stage. If the insulation is coming apart at the coils then it will be bad all over the entire harness including inside the rubber mouldings under the coild/plug lead cover. You don't wont to have to replace the computer if money is the object. I tried following your advice to repair it as per your photo's but it goes much deeper than just their, my advice is borrow the money save your car and replace the harness.

 

Hi, I would like to point out that waether you can afford it or not one must replace the whole harness once it gets to that stage. If the insulation is coming apart at the coils then it will be bad all over the entire harness including inside the rubber mouldings under the coild/plug lead cover. You don't wont to have to replace the computer if money is the object. I tried following your advice to repair it as per your photo's but it goes much deeper than just their, my advice is borrow the money save your car and replace the harness.

That's true, the chances for success on this repair depend a lot on your skill level with wiring.

 

Wiring Harness Problems

Cut and paste this website in your browser you would be amazed at the problems being caused by these faulty wiring harnesses!

Gas leaks, wires shorting, engine fires!

I need to replace mine, over a four day period one tank of gas which usually yields 370 miles, ran out of gas at 155 miles. Realized I had a leak, had the car towed to the house. SRS is malfunctioning, engine surging, fuel guage not working. Car has only 73,000 miles and it has been kept up immaculately, no engine dust. I am a little hesitant to just repair it at this point but I do not have an extra $1,500 laying around to replace it.


http://users.adelphia.net/~infoage1/complaints_nhtsa_mercedes_wiring_harness_failures_1991_1997.html

 

Bottom line here is that Mercedes never did a recall, and the number of cars affected is unbelievable - years 91-97 all models. Cars stalling on the freeway, fires...what happened to safety???

 

Just for clarification, I've just bought two W202s, first one a 1996 1.8 Elegance saloon, 2nd a 1999 C230Sport Kompressor estate, from above quote it appears 1999 isn't going to have the wiring loom issue, but how can I tell by checking part numbers on loom of 1996 car if it might be a problem waiting in the side wings?


P

 

Take a stand!

Has anyone heard about or thought about making a class action case?

 

I think the fact that it affects so many cars is precisely the reason why they never recalled it on their own. And since nobody ever persued it with the NHTSA, MB wasn't forced to recall it either.

Since we're talking about cars that were built 10-15 years ago, I highly doubt that the NHTSA would do anything now, much less MB voluntarily recalling it themselves.

It's a bummer, really. I still like Mercedes, but the next one that I buy will be a 1998 or newer.

 

Did it !

Made a new harness for my C-280, used the original connectors, spliced the wires (automotive heat ressistent) next to the plugs (connections) with solder and heat shrink tubing, took about 4 days to complete the project, car started on the first try, no trouble codes present, car is performing GREAT, car now has a steady idle of 550 rpm. Moral of this story ? You can DIY !
Ed

Removing the old one:

It's Off:

Repairing : Top of picture, Injectors and Coil plugs (red wire) repaired.

P.S It's important to take many pics, it helps solve repair and installation doubts !

 

Wow, that's awesome! Would you consider offering a harness rebuild service? I would be interested in being your first paying customer.

It would also be cool to know what brand and guage of wire you used, as well as the name of the company you bought it from.

Also, do you have more pics that you can post?

 

I own a mb c-220, 1995
I need the harness that goes to the instrument cluster ( all gauges )
Could you make one for my car ?

 

"Would you consider offering a harness rebuild service?" It wouldn't be a bad idea, but for now, I will stick with my day job, plus I live in Brazil, a little too far ! LOL.
In reference to your questions, I used 3 different guages of wire 14,16,18, the original harness uses these sizes and a 12 gauge for one of the grounds, I didn't touch the MAF sensor wire and a couple others, for they were in good shape, the critical ones are the ones that ride next to the engine block, like injectors, coil, etc.. there are a few connectors that you can open and solder the new wire at the terminal. There is one sensor that uses 8 wires,I beleive it's the idle speed sensor, I had to cut it open with a Dremel tool, in order to get REAL close to the terminals, the shielding on these wires were cracked all the way to the connector, after the repair, I rapped the wires with a special rubber tape, to build some volume, so that the clip that holds the connector to the sensor could grab.
One of the difficulties I had, was in disassembling the harness at a junction box located on the left fender (picture below), DO NOT force it ! it comes a part easily, once you figure it out.
I bought all the wires, shrink tubing, special tapes from one source http://www.waytekwire.com/

TK, Ed

 

Does anyone know a good source of supply for the harness other than the dealer? I just took off my transmission harness, damm it was bad! I dont know how the darn thing even worked. I couldnt leave it as it was so I pulled it out and my local stealer wants $175.00 plus tax.

Please advice.

 

Bad wiring harness

mbusa.com told me to take my car to the dealor to have it inspected and they might help pay for the repair. I knew it was the harness but wanted to know if any other parts were damaged. After inspection of my very low miles, immaculate condition(you can eat off the engine) C280, they said they cant check for any other parts failure until the harness is replaced. Is this true? Well mbusa denied the claim which I kinda expected, but waisted the 120.00 for diaognoses. I want to know how to order the one in thailand for 400.00 new. HELP please ...Surfma

 

mbusa.com told me to take my car to the dealor to have it inspected and they might help pay for the repair. I knew it was the harness but wanted to know if any other parts were damaged. After inspection of my very low miles, immaculate condition(you can eat off the engine) C280, they said they cant check for any other parts failure until the harness is replaced. Is this true? Well mbusa denied the claim which I kinda expected, but waisted the 120.00 for diaognoses. I want to know how to order the one in thailand for 400.00 new. HELP please ...Surfma

THis is true... I have had a similar problem and I had to fix the harness first and then I was able to trouble shoot the rest of the car..

GOOD LUCK! I rewired my harness myself... Running great!

 

Just be careful with the replacement harness. I am told by my (usually) reputable parts guy that MB went through a couple of vendors before they were satisfied with the quality of the harnesses. FWIW, I looked at mine (going on next week) and it is manufactured in Poland...

 

Edumen,

Thanks for sharing your research and information!

I've got a bad wire (or connecter) to the crankshaft angle sensor (the engine cuts when I pull on this wire). This wire seems to be solid molded plastic insulation encapsulating the two(?) center wires. The connecter also seems to be molded and unable to be opened to be re-wired.

How did you tackle this task?

 

worst nightmar

bought a c280 from my a private owner and after 1 week car wont go over 30 mph so take it to the dealership and find wire harneis is bad so i finally bought one brand new for 950 dollers and i have the mreceds guy come to my house and c hange it and the car wont even start no more it cranks everythign works but it cuts out when ur cranking it even with the automatic car stared.. it just cuts out when ur cranking so i took it to the mb dealership and its been abot 2 weeks with no info on what couid be the problem. what do u guys think couid be the problem its a 1995 c280 with onle 95000 miles .... ?