muhri

WoW - well done to all and best of all, a happy ending.

efiftyfizzle

That's poor engineering in my opinion. Yes, it may be an isolated incident, but the way these cars are meant to be driven (under track usage and lots of spirited driving), something that could cause that much catastrophic failure should be protected a lot better.

thebishman

surfah

Agreed isolated incident and not indicative of a systemic issue like my 991 GT3 engine.

benzbell

Just a follow up after 3,395 miles now. No problem - fixed. Tech was right it was a one off situation. Was a crazy ordeal, but it's all behind me now.

JeremyH

Or maybe not a one-off... I’ve been stranded on the North London Orbital for five hours and I’ve just been shown the C63s diags is showing faults all over the shop (approximated wording of errors shown from memory):

Intercooler A comms failure
Throttle actuator B out of range
Coolant pump failure
Misfire cylinders 1, 2, and 3
Misfire cylinders random
Turbo A pressure low
[Electronic rear differential inoperative]
[Collision avoidance warning system inoperative]
[Traction control inoperative (this, combined with the engine starting to misfire and the diff suddenly becoming inoperative could have worked out very differently accelerating hard out of the roundabout I was on!)]

Hundreds of faults across multiple systems recorded looks like a CAN-bus issue to me. Now waiting for a tow truck before they can organise a courtesy car. Did I mention it is getting cold out here?!


[The errors in brackets were displayed on the dashboard, but not in the diagnostics]

JeremyH

Well, I’ve now been told they can’t get me a tow truck for another two hours and they will then will organise a car for me (which is a total wait time at the side of the road approx. 9 hours). I’ve given up and booked a hotel room, they're going to sort this out in the morning. Now I know why we buy AMG’s, not.

Surge

Why did you post this here? This should be in the C63 W205 thread.

JeremyH

It was related to my previous post about my car showing exactly the same symptoms, which shares the same engine and electrical system. The fact AMG left me on the North London Orbital for 24 hours was a result of this fault. The fault (and the lack of a decent recovery service) is likely to be common to both cars.

wizee

The engines are similar but not the same (wet vs dry sump), and the wire routing should be completely different (C class is very different from AMG GT). The problem in this thread had nothing to do with the engine or ECUs anyway. Maybe you have/had a chafed wire problem too, but it’s not going to be the same wire in the same spot because the cars are different. Since you posted a while back, I assume its fixed now, so you may as well share what the problem with your car was.

I experienced a similar but less severe problem in my “old” BMW M240i last year caused by a bad chassis ground. The wipers, headlights, and some
computers went completely haywire due to a faulty chassis ground, but fortunately it didn’t affect the CAN bus. It was a one-off instance and they fixed it.

JeremyH

Agreed, the wire routing would likely be different, but the faults appear related, which is why I posted in this thread. I think a wet vs dry sump is a red herring here, but the electrical systems' similarity for these engines may be relevant - as does the relatively hard-sprung nature of the suspension of both cars.

After fourteen days or so, Mercedes came back saying the car was fixed, the problem was 'a blown fuse to the auxiliary coolant pump' and they 'rewired' something. The fact it was in there for two weeks and the use of the word 'rewiring', coupled with the sheer number of recorded faults (several hundred), suggests to me that there was a short to ground (likely the aux coolant pump wiring). In which case, I would guess this is could be a very similar issue, just a different wire rubbing against a piece of sharp metal.

I wasn't provided any written information about the repair.

mbamggt

why is your post here? your post should be at bmw m240i section. but since you are here please do share your experience.

jemilhorn

I had nearly the exact problem as the original post from Benzbell. The problem was finally diagnosed as a frayed CAN cable located on the drivers side, rear hatch area. The cable was shorting to the frame due to abrasion, and the short to ground was intermittent. (Details about the cable are included early in this post.) This intermittent fault caused multiple error codes including; Electronic Rear Differential Lock Inoperative, Transmission Failure, Collision Avoidance System Inactive, Malfunction, and automatic shifting to "N", starter lockout, no start at all, etc. A short time later, the car would start and drive normally. But the next time it wouldn't start at all and throw multiple error codes again. When the cable vibrated/moved enough to clear the short, the car worked normally. The GTS has 20,000 miles and is driven infrequently. It is still at the dealer for the cable repair. We will see if this actually remedies the problem. However, the issue can be duplicated by moving the cable around, so obviously this is at least part of the fix.

Surge

It would be great if you could post a photo of the frayed cable!

JeremyH

Sounds like you're getting the same errors I was, although mine would also on occasion go into limp-home mode and cut the power dramatically. While getting the issue diagnosed was a pain, assuming they were both caused by a similar short, you should find the problem has been resolved when you get the car back. Unfortunately, I can't say for sure what happened with mine as they weren't very forthcoming (other than saying the aux coolant pump fuse had blown and that they replaced and rewired the pump).

Hendrik Koster

I have had to resolve similar issues when my oil level/temperature sensors where not sending any data to the ECU (caused by a bad signal wire between the sensors and ECU) In order to find the bad wire and solving the issue by running a by-pass wire I made a pin out overlay of all the pins inside the ECU.

https://mbworld.org/forums/coupe-roa...u-pin-out.html

If the ECU is getting bad or in complete signals all kind of side effects start to happen.

Best H

JeremyH

There are a lot of pins on that connector!

jemilhorn

I picked up the GTS at the dealer this morning. The cable repair is already completed so I cannot get a photo of the abraded wire. The repair included removing the cable bundle, insulating the abraded cable, and then wrapping the cable bundle with a strip of foam insulation. During troubleshooting, the cable could be moved around, and the car would throw error codes and/or shut down. It could be restarted when the cable was moved to another position, only to fail again when released. The cable is located in the rear tool compartment, drivers side. Remove the left rear side panel where the tow hook is stored. Once removed you have a clear view of a fuse block and various cable bundles. The abraded cable was in the upper section of this area and close to the fuse block connector. I can send a pic of the repair, but I doubt it will be of any use due to the very tight quarters. The cable that was shorting to ground was one of the two CAN leads. This two conductor network cable connects all modules and sensors to the data bus that feeds the ECU. The cable carries a high or low signal, and when grounded, that confuses the ECU with multiple failure codes. I'm certain if a MB tech is reading this they are saying I am completely misinformed. Well, so be it. But, this repair solved my problem, and the car is back to normal, with a confirmed insulation cut on the main bus cable due to abrasion on the frame. I'm an electronics engineer, and I know two things: 1. Vehicle wiring on new cars is a holy nightmare, and 2. But for a post on this forum, my car might still be at the dealership.

Hendrik Koster

These are the hardest things to find out about and to resolve them as most of the times there is no particular error code pointing to any of this. Normally you would not expect an abraded wire. It's important to understand that failures like these can have a domino effect on the signals that the ECU requires/processes to have our cars function properly. Having been there and done that I'm missing the old fashioned hard copy wiring schematics.

But do appreciate the fact that you took the time to share your experience here.

Thank you,

Best H

BBS63

Wow. Just wow. Thank God the tech was able to find it that fast and fix it. Sounds to me like you have a great idea for the movie Hangover IV.
I mean it all happened in Vegas. LOL

jemilhorn

To JeremyH: I had a "limp mode" issue last year with the GTS. There were absolutely no error codes, but the car would not generate more than 150 HP. After a couple of days at the dealership, no progress was made, so they hooked up to the MB diagnostic computer in Germany and let the techs there look at the engine parameters. Nothing was found, so they "re-flashed" the fuel computer. That fixed the problem, and I have had no similar issues since. No indication as to what might have caused the fuel computer to lose it's mind, but the re-flash fixed it. Too many computers, too many cables, too many connectors, too many sensors, too many..... And I have worked with manufacturing computer design and control systems for years. But vehicle ECU's, modules, and CAN's are an entirely different matter.

JeremyH

I have to admit, it was driving me nuts. I would overtake someone and then find the power cut dramatically when I slowed down after the manoeuvre - I was starting to get concerned about it happening while I was overtaking (it never did). My estimate was about 150bhp too, which makes an almost 2 tonne car feel very slow!

Once the car came back from the dealer following its complete ECU meltdown (I seem to recall the breakdown service said there were some errors recorded 100's of times in the log), it never happened again.

MalibuScott

I always ask for replaced parts. As to those the dealer says must be sent back to the factory I ask to inspect them.