komara

Hi Guys,

I just bought this car 3 days ago and it did drive beautiful for over 400 Miles so far.

Today going to work in the morning tried starting but it didnt start. It behaved as it was low battery. I got my meter and measure the battery it was 12.7V which is good. the battery itself is about 1 year old.

every time i try starting, it clicks and make a tiny crank then stops. doesnt complete the crank. and then the Esp or abs showed in operative.

I checked the CANbus and the area for mositure and water all is dry and clean.

then after about 2 hours fiddling around it started like no issues at all. no codes or engine light.

took it for a spin and it drives like its old self. Parked and every two hours would go and check if it would start all is good.

Now after being parked for 4 hours same thing happened again tiny little crank and no start.

I tried shorting the starter relay as it might be ESL problem it does crank but it doesnt start. Now im out of ideas.

Any help or does anyone have seen this issue before. i took a video of what it does.


I hate that my first post is crying for help but I appreciate your pointers.

My CLA250 Got totaled the day i made an interview for a job that is 75 Miles away.

I Bought this one as a commuter and really need to get going again quickly.

Best regards,
Karim

Odd Piggy

Did you scan to see if any codes are showing up?

JettaRed

iTrader: (1)

Failing starter? Seems we had another thread recently with similar problems.

komara

Hi Odd Piggy,

I did scan the car with my cheapo reader and there is no errors or faults originally.

but after multiple times trying to crank it i saw a pending code about an hour after posting this thread

Code is U0002 " High Speed CAN" and i cant pin point it to somewhere. As i mentioned i checked the can busses both driver and passenger they are dry and no oxidization. i even measured the busses and they read 60Ohm which is a healthy can termination.

I`m an engineer who works with CANbus all the time. Unless there is a bus i didnt measure or some weird module failed shorted overnight. i cant pinpoint where the issue is.

thanks

komara

im thinking this but two things.

I did jump the starter relay and it does crank the engine with no issues or problems the second is there is some errors on ESP and now Lane assist. so i think it more electrical than a failing starter.

JettaRed

iTrader: (1)

WARNING: The link I previously posted may go to a site containing malware. Do not click!

I am deleting the content of this post. It may be misleading.

Odd Piggy

Since the stater cranks the engine when the relay is jumped, maybe it’s the relay itself? That’s a fairly inexpensive part just to swap out.

komara

good point, except the relay does work as when starting with a key the relay closes and the starter does make a clunk sound trying to crank.

i think it is related to a starting command or can message that doesnt get sent correctly and reliably . i cant hear the fuel pump priming as well which is on CANbus and controlled by a message. i checked the fuel pump it is working OK if i jump it.

from what im seeing from the historic and error codes they are CANbus related. I managed to get the full wiring for the CANbus network through out the car and will test each one of them for shorts and prober termination.

any other ideas are more than welcome and i wish if this weird issue showed itself before.

thanks,
Karim

Odd Piggy

Check your CANBUS diagrams to be sure, but once the DAS (you have DAS 3) has decided that the conditions to start are satisfied and the relay is actuated, there’s not much between there and the starter. If the starter clunks but does not turn the engine over, it’s trying to start but cannot physically do it.
It might be easier for you to dive into the CANBUS analysis, but here’s where I would go if the car was in my garage showing intermittent starting problems:
1-I would change the relay just in case. Only minutes of time and small sunk cost ($12-$20).
2-High resistance in the starter power circuit or ground. Break & clean the few connections in this circuit.
3-Starter solenoid is bad.
4-Starter throw out is worn and not properly engaging the starting ring.
5-Starter has a bad winding and will spin the engine if it does not stop on the bad winding, but fails when it does.
3-4-5 All require the starter to be out of the car, so at that point I would probably get a rebuilt starter to get the vehicle back in service.
Good hunting!

komara

Hi guys, so the mystery continues today the car started just fine like there is no issues at all not a single error or warning light

for about 6 hours then tried starting it again same old problem happened one more time.

i invested in 400 dollars fancier scanner and my suspicion was confirmed.


It is a CANBUS issue see the attached error messages from the full car scan.






Now it is a matter of finding what shorts/loads the bus

i managed to get the canbus wiring through out the car and i think it is around CANBUS-E

which has the camera and steering column, instrument cluster

the big guys are OK thank god so far.

will report back when i find the issue.

thanks,
Karim

Odd Piggy

Does the car have a history of water damage? Many of the CANBUS connections are in the rails under the door frame. Even wet carpets from a clogged AC drain can get into there and corrode the connections.

Others have reported a “DTC storm” from CANBUS problems and your case may fit.

The TCM is in the DAS. A failure there could cause a no start. So could the steering column if that circuit contains the ESL.

What puzzles me is that you report a clunk from the starter. That sounds like the starter is getting power. At that point the engine should turn over whether it starts or not.

On the DTC code list, all the codes are stored. Do they return if cleared?

These are just my thoughts, so no need to reply until you get a solution.

JettaRed

iTrader: (1)

Did you run a CarFax on the car? I agree that a clean CarFax does not mean the car is clean, but a "dirty" CarFax certainly means the car has/had problems. I agree with Piggy that you should check for signs of water. Pull up the carpet in the back and feel if the foam feels damp. The sills on the door pull off and the rear seat comes out. That'll loosen the carpet enough to pull it up a bit. Check this thread here: https://mbworld.org/forums/c-class-w...er-s-side.html

komara

that is the very first thing i inspected when the problem started.

The under carpet both Driver and passenger are Bone Dry. no condensation marks visible i went all the way to inspect all 5 CAN bus termination blocks and they are clean and dry.

if the car is in "I`m not gonna start mode", Yes the DLC codes will remain if cleared they will come back instantly and always the same modules/ errors.

but when the car is in IM OK i Will start now . the DLC codes will be historic and when clearing they disappear instantly and never come back "Of course as the car doesn't flip on me and change its mind"

here is my explanation for the clunk and the start process.

the CAN Bus issue is not "Completely down or Dead"

the issue is it comes and goes within the failure mode. i mean instead of having constant stable stream of communication messages it will be dropping frames. i know this as yesterday when i checked the car, the car was warm and when the issue came back and wouldn't start and clicks only
i can see the temp gauge bouncing up and down. up to what it should show as temperature and down as there is no info to show.

so back to when trying to start, at the start command all conditions has to be met, the signal initially are present and complete and now we try to start, the starter clunk then the communication get lost and now the conditions we are trying to meet some of them are missing and now the DAS itself is stopping the start command.

I really wish it was water condensation or puddle this could have been straight forward and easy fix, it just comes and goes and even when it happens it is not completely gone as i can talk to the module even tho there is communication issues.

because i can talk to them when the bus is kinda working.

hope this help or makes sense

Karim

komara

I did run a Carfax on it before going to see it. the car is 88K miles and not a single incident or damage on it. the car was dealer maintained and it did spend a whole last year in MB long beach, when i asked about it it was due to Trimming chain and tensioner replacement. mechanical engine problem.

i will try to call the service advisor in MB and get more history and information regarding the issue.

thanks
karim

Odd Piggy

Intermittent module communication problems are the worst. @Marktee bought a 2012 C250 flood victim at auction. He’s a technical guy and thought he could sort out the issues. Two years later he was still chasing phantoms. Comparing the two situations makes me wonder if your car has a whitewashed title history.

Maybe you could PM him to see if he’s got any suggestions. Looks like he took apart every connection in the car.

Did you buy the car at the MB dealer? They have somewhat of a reputation to uphold. Maybe you could go back to them and plead your case. You may have bought a used car without a warranty, but it’s still supposed to be useable.

komara

Hi Guys,

I finally found the problem and Solved the issue, Knocking on wood its been a Full week and it didn't happen again.

So when the car is working No issues or codes are stored. no codes at all in any of the modules.

But when the issue present itself, there are Tons of CAN Bus errors and since there is no wires, distribution box, or water condensation the issue was heading toward a Module that shorts out or somehow load the CANbus.

when the issue is present i measure the termination resistance in all 11 CAN bus networks and they were all perfect 60 Ohm.

since some modules did have the CAN bus errors and some has no errors at all. i figured it is one of the GATING modules, meaning one module that filter messages and connect between Busses.

In this CAR Gating Modules are, F-SAM, Central Gate way module, and some others but from my diagnosis everything pointed fingers towards the Central Gateway Module.

It is Located in the Fusebox 90 Degrees of the F- SAM, Since this car has the common problem of water going inside the same I decided last Saturday to open up the same and see if there is any condensation or water or corrosion on the Modules.

I opened the F-SAM and found traces that someone was there before and it isn't Factory looking. the about 25 harnesses were entangled and it was a mess.

But it was DRY and clean i started taking connector by connector to get the F-SAM Out and inspect it. each connector was seated correctly snug and firm as it should be.

While i was taking connectors off one of them " White 6 Pin connector" just flew off and unplugged itself without touching it.

well Loose connector might be it and run havoc across the whole car but wasn't very confident it was the issue.

kept going and got the F-SAM out and inspected it it was super clean and no issues or residue at all every thing is OK condition there.

i decided to put everything back and un tangled the harnesses and properly installing each harness and Snug them in as they should be.

And that was it, 8 days later today the car starts every time as it should be, No more CANBUS errors and everything is working as intended.

Loose connector that was serviced by the dealer was causing all this issues. I called the dealer that serviced the car and they confirmed they replaced the F-SAM at some time due to Water condensation.

but seriously the quality of assembling the F-Sam together again was terrible. i didn't take pictures unfortunately due to wanting to find the problem and didn't see something very visible that screams I'm the problem.

Just really never trusted anyone to work on my cars, i service and maintain my cars myself over the past 15 years. regardless how complicated or requires tools.

anyway thanks for your help and i wanted to come back and report the issue found hopefully no more funny business.

Karim

TimC300

Thanks for the follow up with what is hopefully the fix.

I do not like having others work on my car and will try to do everything myself. The only time I took my Mercedes somewhere was to have a front tire pressure sensor swapped out. I called around and the small tire shop down in town said only $20 to replace it since I was bringing a new sensor, I just needed it replaced. Long story short I went to remove that wheel the following weekend to replace the sway bar links and I could not get the lug nuts off, im not a weak guy and ended up using my breaker bar with a 3' piece of pipe to remove 3 of them. Thats insane. I keep my 1/2" torque wrench in the trunk specifically to properly tighten the lug nuts since I have a habit of over tightening them. Since that mess I taught myself how to swap the other sensors myself using a floor jack to push the tire from the rim to reach the sensors.

As far as water getting in the car I was at Lowes buying fertilizer last weekend and opened the trunk to load the bags in, I grabbed my gloves I have tucked in the little netted compartment on the left side near the tail light and they were wet, I felt the carpet underneath and it was wet also. I haven't tracked down where its coming in from yet. I checked the seal along the trunk lid and looks fine. I'm always washing my car and wondering if I'm blowing water in somehow. I also park my car on a slant, trunk sits up higher so wondering if when it rains the waters not draining right,.

CaliBenzDriver

KARIM: THIS IS EXCELLENT WORK RIGHT THERE!!


You really got lucky finding the loose F-SAM connector. Harness organization always look messy because of so much happening inside small tub enclosure.

I really like the part where you describe tracing issues back to GATEWAY 👍
This is exactly what is causing poor performance. When one of the members of usually CANBus-B is disrupted by a wonky door module gone wild, the whole Gateway functions are impacted by "I/O Storms". Once that happens multiple functions begin to actup... chaos!

EX 1: The Headlight module needs to read speed not simply car speed but all four individual wheels. It does that through gateway to go talk to ABS Module. That's a lot of busy traffic.

EX 2: ECU needs to know the current battery voltage.
It does not simply read it directly...
- Instead ECU requests Batt Voltage from F-SAM over CANBus-C
- ​​F-SAM translates requests through CGW Gateway from bus C to B
- In turn F-SAM chats with R-SAM over CANBus-B to read the LIN battery sensor.
This "almost nearly works when new" but ECU rapidly develops performance issues accessing unavailable slow data.
This is one of the sources of poor network performance affecting engine timing.

> Practical TIP:
fault tolerance impacts performance thus you want to have NO faults on any of your CANBus network.

Enjoy, "Cali".
​​​​​ ​​​​​​

CaliBenzDriver

Best advice is to track water leak spraying from the bottom up all the way to

• glass seal
• roof seems
• sunroof drain

Check the quality of the nearby GND screws. They are poor to begin with and get oxidized from humidity... after that:. it's network chaos!
🤞

komara

Its Hilarious that the car never showed any problems within the first three days of ownership.

and another hilarious coincidence. that I'm an analog HW engineer for electronics mostly consumer and RF and my CANBUS experience is through my personal car projects and through my EV conversions.

yes i converted two cars to electric including a very CANBUS dependent 2010 BMW 530I

so glad that my personal projects got me enough experience to troubleshoot this weird CAN BUS issue.

now im doing just normal service on the car.

Engine mounts, Belts, Spark Plugs, Filters and SWAY BAR LINKS which all are typical issues in this model

Thanks Guys
Karim

TimC300

Things like sway bar links, engine mounts, brake pads, rotors etc I would look at FCP Euro to buy for there lifetime warranty. They are usually higher priced but totally worth it. I was recently pricing out parts on there and it looks like there prices have gone up on almost everything I bought, so I would have to pay a little extra.

For everything else I like eEuro Parts. They typically have lower prices for the same items/brand. They have the Mann oil filters for only $6.50, ill always buy 1 or2 if im already placing an order to stock up. I doubt ill send back a used oil filter so no reason to pay almost double from FCP. And if you never bought from eEuroparts before they have $10 credit just for signing up with them.

https://eeuroparts.com/?wlpr_ref=eEuro_atc0xpy6j

komara

Already put a 750$ worht of parts and service through FCP euro.

they are my go to for parts.

I already did the Engine mounts yesterday and so much nicer now.

Thanks,
Karim

CaliBenzDriver

Really good thread 👏
In the rubber schedule, add:
tranny mount
control arms


> Save some troubles:
As you work around the car outside, waterproof as many harness connectors you come near in both front/back bumpers.
Water gets into modules through the dried-out wiring seals.

komara

Great

thank you for the tip.

I did already the Tranny mount with the engine mounts, Control arms looks ok as of now.