Command shutting down with other wierd stuff happening

[L John]

Hi folks, hope you're all doing well, I have a problem with command shutting down on my 2008 C class.
It starts up ok but after a random time of around 2 minutes to 10 minutes a pop up message says 'command is now shutting down' then the screen closes.
After this happens my rear indicators stop working on both sides, message shows rear indicator fault after I try to use them. They work fine at start up and are factory leds. My fuel gauge starts to randomly read normal, low or show empty, changing occasionally, and my headlights come on even with the selector set to off.

I know there's a fault on these cars where the brown wire on the harness that connects to the rear light cluster and it was showing signs of overheating so I did the wire bypass that our good friend Malcolm (RIP) recommended many years ago.

Unfortunately it still shuts down and does the other weird stuff.
I'll get it booked in to a good garage well known for doing good work on Mercedes but that will have to wait a couple of weeks.

Until then has anyone got any ides what the issue could be?
Thanks.

 

[Taffy7hfa]

How's the battery ?

 

[L John]

Good question, it's a good battery as far as I know. It's about 2 years old and always starts with no issues.
Car lives in the garage and is only generally used at weekends. Battery seems strong, it turns over quick and starts straight away.

 

[L John]

I'm thinking a bad connection somewhere or a something shorting to earth, last thought was a module failing, hopefully not the latter.

 

[AMGeed]

I'm thinking the battery is partly discharged and needs putting on charge.
Have you checked the voltage before starting the car? Fully charged should read 12.6v.

 

[robin.large]

I'm assuming shutdown is when you are driving? I'd suggest seeing how long it works without driving anywhere? If it does 30 minutes or so then most likely an earth or power issue. If on the other hand it fails when stationary then think module or similar overheating.?

Sent from my KB2000 using Tapatalk

 

[L John]

Thanks for the replies, I drove it about 8 hours ago and just checked the battery voltage. It was sitting at 12.7v I started the engine and it went to 14.2v a little higher than I expected but not a problem I think?
I've connected my smart charger to it anyway, it should tell me if there's a problem.
In the morning I'll also check the battery terminals are tight and secure.
Yes it's always when I'm driving Robin, not tried it stationary but I'll try it and see what happens.
The other weird things that go with it, like the headlights coming on make me think a module is getting confused either by a poor harness contact or moisture getting in somewhere.
An electronic component overheating is a possibility Robin, maybe a poor heatsink or faulty electrolytic capacitor swelling?
I guess that would mean a new board from a dealer or repair shop, not much gets repaired these days, they just replace a board.

Like I said, it will be a couple of weeks and I'll probably be going to Prestige motors at Stockton on tees, they have good reports and I've been there before and they were excellent.
Hopefully it wont have to go to the main dealers as I can see then shaking my wallet hard over this.

I'll report back on the outcome and look forward to further discussion for any more ideas.
Thanks guys.

 

[Blobcat]

Sounds a bit Like a faulty / water damaged SAM - when water gets into one random things happen

 

[Uncle Benz]

I’ll second the SAM suggestion. Open up and check for damp or water ingress

 

[L John]

Thanks, sounds like a strong possibility. Where is SAM located please?

 

[L John]

Checked battery and battery posts, all tight and clean. Car sits in a garage and only gets used for drives on nice days so I doubt water has got in unless its condensation from temperature changes?
I didn't try it without driving but checked everything else that I could, so it's now booked in on Friday 11th at Prestige Motors.
I'll report back when it's sorted, thanks again for the help and suggestions.

 

[Alfie]

Sounds a bit Like a faulty / water damaged SAM - when water gets into one random things happen

Id agree fully with this although rear lights are the rear SAM but Comand will be the front SAM.

SAM is either in the footwell or underneath the main fusebox!

 

[L John]

Thanks, just got my fingers crossed it doesn't need a new module or modules as I'm sure that will cause the price to get silly.
The car is in great condition but probably only worth around £6000 now

 

[L John]

Just found this.
https://www.reddit.com/r/mercedes_benz/comments/68s04p
Seems someone else has had the same issue with the same year W204.
It's going in on Friday, hopefully a simple fix. Bad earth somewhere?

 

[L John]

Another one with the same problem, or maybe the same person with a different name?

 

[malcolm E53 AMG]

Is it possible to try another battery. I had a Ford Focus with a similar issue and it turned out to be a voltage drop on the battery, the symptoms were a number of spurious faults ie, radio turning off and other electrical items failing, yet the car would start ok. A new battery solved the problem

 

[L John]

Forgot to mention, I sat in the car with the ignition on but not driving as suggested by Robin.large, the comand shut down after about 5 minutes but then opened and restarted a few seconds later. This repeated several times.
With that in mind Malcolm210, yes I can connect a jump start battery to it and try it again.
Many thanks everyone for the suggestions.

 

[L John]

I went to my local indi.
The engine management light has also been on for about 6 months as well so I asked them to look at that too.

They said the thermostatic valve is faulty causing the engine management light to stay on. £320 to sort that.
They said after that they will have to look at the software and if they have to reprogram it, that costs another £140.
Then they're going to do a battery test and said the problems relating to the comand shutting down and rear indicators etc all relate to the front sam.

Still at the indi, I'll keep you posted....

 

[L John]

Latest update.
Info back from indi, sorting the engine management light needed a new thermostatic control valve to be fitted and software needed to be reprogrammed, £500 for that bit.

Mechanic says he tried to reprogram the rear sam but it fails during update.
He says all the faults now relate to the rear sam.
Exchange rear sam module and coding etc will cost another £550
Actual total quoted is £1046.
Bit more than I was hoping for on a 13 year old car.

 

[L John]

Just got the car back.
Rear sam was replaced with an exchange unit from Mercedes.
Total cost, just over a thousand pound all in for sorting this issue and the pre existing problem of an engine warning light showing.