Well everyone, I have given up. The white towel has been tossed. Oh, you're curious you say? Alright, take a seat... (I'm Chris Haaaaaansen)

It all started with my idea to rid myself of my 2013 Focus ST (with the ST3 package) with 7k miles for a 2005 C55 with 77k miles. The Focus was fun, I enjoyed it for some months, but then... I dunno, I guess boredom set it. As much fun as the ST was to drive, I had been spoiled by my previous vehicles in terms of power (Pontiac G8 GT, Neon SRT-4 with plenty of go-fast goodies). Browsing the web one day, I started thinking about getting an AMG. I've always loved the W203's, they were my favorite C class. I was determined to find one. First one I saw was being sold for WAY too much ($21k for an '06 with 65k. Loaded. Black on black.). I went to look at it anyways and see how a C55 drives. The condition of the car was far from what would be expected for that asking price. All 4 rotors needed to be changed, pads were donezo, paint was in "eh" shape. I test drove it and loved the ride! Stiff, but not so much so (that's what she said?), the power and torque I was used to, and very comfy on the inside. Got back to the dealer and we negotiated for a while. No way in hell I was going to pay the asking price!! I also told them the brakes needed to be changed, and they said they'd take care of it. I went home and mulled the vehicle over for a few days and decided to have it inspected, because if it was in pristine mechanical shape (a boy can dream, don't judge me!), I could maybe consider it. Communicated this to the dealer and returned the following Saturday. I arrive there with a buddy and grab the keys, put it in the ignition and all is well... until I start the car. The engine comes alive but all, I mean ****ing ALL, electronics are dead. D-E-A-D, dead. Tach? Nope. Speedo? Nope. Windows, radio, seat adjustment? Nope, nope, nope. I call the sales manager over and show her the issue. Her response is probably the funniest/dumbest **** I've ever heard in my life. She says, as I point to the tach, "Well, it's because the vehicle isn't moving." Yes. Yes, folks. This woman just told me that the TACHOMETER is not working because the vehicle ISN'T MOVING. I was obviously dumbfounded, so I just sat there in the driver's seat, thinking that this is probably how an aneurysm happens (Lewis Black can take credit for that one). She then turns to me and says, "Well, ain't you taking it to a mechanic??". Needless to say, I did not get the car. Fast forward a few weeks and a find another for sale. Go visit the dealer and they were simply awesome from the get-go. Friendly, knowledgeable, and specialists with German vehicles. We do all the paperwork and I take home my '05 C55 with 77k. I enjoyed the car for a couple of weeks (washed, clay barred, waxed). I was smitten and enamored. Oh, and it came with Kleemann headers and tune. It ROASTED tires. I order aftermarket headlights, LEDs for the interior, side markers, and license plate. I ****ing loved it. I got the resonator deleted... and then I REALLY ****ing loved it!! Until one day (yes, here we go) when I'm driving along on a Friday night and suddenly the tach dies and I get 3 messages on the dash: ABS display malfunction; ESP display malfunction; Brake Wear Sensor malfunction. Oh, and it was also stuck in whatever gear I was in when it happened. I contact the dealer/mechanic shop and they ask me to bring the car in the following day. I take it to them, and that's where it stays for the next 4 (yes, 4. Four. Quatro.) months. They replaced every possible thing that could be causing the issue, they had conference calls with MB North America, they busted their asses trying to figure this thing out. Mind you, these guys are not amateurs by any stretch of the imagination, much the opposite, they've been working on German cars (80% MBs) for over 35 years. They have never been stumped by an automotive issue, and my car did it. It stumped everyone. Eventually, I told them I was tired. Tired of hoping it's fixed, tired of waiting, tired of touching base, tired, tired, tired.

Now, I know some may want to chime in an suggest the potential culprits of this issue, so I'll just go ahead and outline what has been done:

Monitored via STAR on MANY occasions
Replaced ABS/ESP module
Replaced ABS/ESP pump
Replaced third brake light
Replaced brake light diaphragm

Additionally, we've taken in to a specialty shop that focuses solely on MB electronics (component replacement and repairs). They hooked my car up to some enormous machine that read signals from all CAN & SAM systems in the car. They apparently had found something that kept temporarily losing communication with the ABS/ESP system. A repair was done and 2 days later the issue came back. The last thing we've tried is swap out my aftermarket headlights (DEPO, W209 quad projectors) for some stockers and, as of Tuesday, it's behaved.

 

Wheel speed sensors will give the ABS/ESP warning but not put it into limp mode...

What you're saying is the car went into limp mode and stayed in whatever gear it was in. I've had this happen before. It actually happened to me the other day when I punched it after cars and coffee, it stayed in 2nd. I pulled back into the parking lot, turned the car off, waited maybe 30 seconds and turned it back on and it was fine. It happened another time about 6 months ago but I didn't replace anything with it.

I'm not 100% sure on what all triggers limp mode but it's possible that a bad MAF reading could trigger limp mode, try cleaning MAF and TB. Maybe an upstream O2 sensor could trigger it as well.

Low trans fluid will trigger it too. Possibly if you haven't replaced the common leaking pilot bushing on the trans it can not only cause you to lose fluid but eventually damages the TCU, which I suspect would put the car into limp mode.

I'm shocked the STAR wouldn't tell you some diagnostics on which components are causing problems. Did they tell you of any codes that they pulled?

 

The issue was intermittent, and would honestly pop up when the vehicle was warmed up. If I let it cool off for a while, it would go away, only to return eventually.

The MAF unit was also replaced previous to this problem (car kept dying when coming to a stop while the engine was cold).

Trans was checked for leaks and proper level, all in good order there.

The guys at the shop didn't relay to me what code was given from STAR. Many times it wouldn't even throw a code at all! The car would go into limp mode, I'd get the messages, but no CEL.

 

This happened to me this past summer. I was cruising on the highway and all of a sudden my tacho just dropped from 65 to 0 and the car was stuck in 4th gear. I came to a stop light after the exit and it was still in 4th gear. I got the ABS,ESP light too. Had it towed to the dealer and they replaced the ESP module and did the programming for it and haven't had any issues since then (of this sort).


So are you getting rid of it? Selling it back to the dealer or something?

 

Just because you don't get the CEL doesn't mean there aren't codes. There are 1000s of codes that the ECU tracks and logs that don't trigger CELs and are only visible through STAR module.

For example, it'll log things like "3rd gear slipping," "4th gear slipping," and other miscellaneous things. I had all sorts when my buddy and I hooked up the STAR to mine the first time. It was telling me that the alarm siren was not functioning, a couple of the gear slips I had, don't know if that was before I changed the trans fluid which was really dirty or maybe I need to do the PWM solenoid and conductor plate thing, etc. etc.

Anyway, what I'm trying to say is there's a lot of things the car monitors and logs that won't show up as a CEL. The STAR computer should be logging something as the reason why it's giving you the ABS/ESP warning. For example, when I got my ABS/ESP warning the issue was one of the speed sensors but it doesn't give CEL or tell you which wheel. When we hooked up STAR, we pulled up a live logging of each of the four speed sensor inputs, all at 0 since we were stopped. We started driving the car a little bit and watched them all increase except for the front right which stayed at 0, therefore letting us know that was the bad sensor.

 

Yeah, I mentioned the CEL portion just for the sake of being informative.

The shop monitored the car for days via STAR, they had MBNA monitor the car remotely for a few days, they monitored it while driving... and nothing. I believe it kept going back to the ABS/ESP module, but that was replaced with a brand new unit. All the things MBNA suggested they check, had already been double or triple checked.

I purchased the car with 30 day warranty from the dealer (who actually sold the car on consignment, as they can function as a dealer, but focus mainly on repairing German vehicles) so right now we're in the process of finding me a replacement car. The guys were nothing short of fantastic from day one! Always keeping me in the loop on what they're trying, always open to chat, never leaving me hanging. Honestly the BEST shop I've ever dealt with, bar none.

 

Just curious, where are you located?






Have you taken it to a dealer or just the two shops you mentioned?

 

I´ve had the same symptoms several times.

It turned out to be bad contact in a connector between the ECU and the
engine bay.
Several years ago Mercedes had a bullentin on this connector for W203.
The mechanic simply cleaned it out and since then no worries.

Hope this helps.

 

Hey raphman, don't give up yet.

I had the limp mode happen last week at cars and coffee like I was saying. Friday evening I drove the car out and back home and it was fine. Saturday morning I went to the grocery store to grab something and on the way back I was sitting at the last traffic light before turning into my neighborhood and I got ABS/ESP warning, and brake wear warning, wouldn't shift out of first gear and speedo dropped and stayed at 0 but the tacho was still working. So I crawled into my neighborhood at like 3k rpm in 1st gear and got it back into my parking spot and left the car as of now.

So it looks like I'm starting to get the same symptoms as you now. I bought a STAR which according to UPS is arriving Wednesday and I'm going to diagnose and see what messages I'm getting.

I will say lately I've noticed when car is cold the trans is getting the "jerk" real bad and is kinda slippy for the first couple of times I move from a stop and drive but once it's warmed up it drives perfectly fine. I suspect maybe an issue with either that pilot bushing leaking or the common electrical conductor plate issue. I'm thinking I'll probably replace these and the shift solenoids since it's a known problem and see what happens.

I am currently running Valvoline Maxlife synthetic ATF, since I've found on here that it's the same stuff MB puts in their bottle with logo and sells it...someone let me know if this understanding is wrong. But the Maxlife does meet the MB NAG-1 spec and should work fine. Hopefully my problems aren't the result of using this fluid...

Stay posted, I'll let you guys know what I find out later this week with STAR.

amgen, I'll have to look into this electrical contact thing too...

 

Where did you buy a STAR, Mulac? I would love to get one.

 

I got lucky and found a STAR module someone was selling in the classifieds, just need to hook it up to a laptop and install it.

One of the sponsors on here, shardul, sells the whole setup with laptop. A while back it was around $750 or so if I remember correctly, not sure if that price has changed by now.

You can find the STAR module on ebay but you have to make sure you're buying the right one and not some knock off crap, which is tough to do for me at least since I'm not familiar with all of the different versions and crap like that.

 

Mulac all stars you buy aftermarket are knock offs. Even if they have MB logos on them. I am curious though as the dealer had the car for 4 months and they only replaced what seems to be two parts that are even related. What was the hold up? did you decline more parts to be replaced or additional time for diag? Sometimes issues like these could be from some type of connection somewhere in the car too difficult to reach or water damage on connectors somewhere shorting it out. What did the dealer finally end up telling you? I think you left that issue out of the story. it's not really like a dealer to just give up and give the car back....not sure what a brake light diaphragm is either lol.

 

The malfunctioning connector in my car resulted in worn brakepads,
ABS and ESP. It came and went away when turning the car off but got
worse over time: The tacho died, it went into limp home mode and finally the
gearbox locked. Cleaning this connector solved all problems. As I said,
Mercedes issued a bullentin over this several years ago.

 

I'll have to find this bulletin...thanks for letting me know.

 

Correction:

The speedo died, not the tacho...

 

I'm located in NC, and I've just taken to the two shops, as I know MB would charge an arm and a leg to check it all out.

Mulac - thanks for the faith man, and please keep us posted on your findings.

 

That is EXACTLY what happened to me Saturday morning, ABS, ESP, Brake Wear, and speedo at 0. Tacho still worked.

Alright, definitely going to start with cleaning the connector...

 

So you never taken it to the dealer, but you said MB N/A was involved? I think by now you would have spent more money chasing the issue with the parts replaced. Were the parts you replaced new?

 

Yes, the shop I'm dealing with (where I also purchased the car from), has been on the horn with MBNA several times, and all the suggestions they made had already been inspected. The parts replaced were new, yes.

 

amgen, you wouldn't happen to know what the bulletin you are talking about was titled? I know there is a regular w203 bulletins thread I found, trying to see if there is one on there that is the same.

 

I contacted the shop and mentioned that ECU to engine bay connection issue, they responded it was checked within the first few weeks of being in their hands.

 

Mulac, no sorry.

It was my mechanic who told me.

Can´t be that many connections from ECU to enginebay?
Maybe there´s one on the drivers side in the enginebay close to
the windscreen? Worth checking?

 

There shouldn't be I wouldn't think. I would imagine there's a main connection to each fuse box and then they branch off from there to each electrical component. Does anyone happen to know where the physical ECU is located? I guess I could look at a part diagram...

 

I could be wrong but isn´t it behind the radio somewhere?

 

Isn't the ecu in the engine bay opposite side to the battery, located in the fuse box area next to the brake master (at least on the RHD).