Hi guys!

This is my first post here and I'm not sure if there is a similar post to mine but I would appreciate any help or advice. My issues started when I noticed the dashboard displaying message "convenience functions temporarily unavailable" so my stereo would shut off and stuff like that and after awhile it would come back on or after restarting the car. Week later after I noticed these issues it got worse, I got the same message "convenience functions temporarily unavailable" and later it dashboard would turn RED color and displayed "reduced braking effect" then ABS light would come on, ESP and pretty much the whole Christmas tree effect and car eventually died and I was stranded on the side of the road. So I called the roadside assistance guy and he told me it was my Auxiliary battery which is the little battery located under the air vent. So I went and bought a new battery from the dealer $180 later and we replaced the battery and the Dash still displayed the same message "Convenience func. unavailable" and the car would crank for about 7 seconds and wouldn't start. Therefore I got it towed to the Mercedes Stealer they asked my permission to look at the car for $140 to determine what's wrong with it. This is their recommendation to get the vehicle started, first I have to replace CPS ($450) and Alternator voltage regulator($280), and they said if that wouldn't help I might need new alternator($??? or replacement of rear battery($350). After they told me how much it would cost I pretty much told them to F... OFF and jumped in my car to see what the dash will say.

Oddly I was able to start the car at the dealership and drive it back to my house which wasn't that far with the RED dash display and battery icon and saying Visit workshop! When I got home I replaced the CPS which I bought at the local auto parts store and the vehicle still cranks but doesn't start.
So far I already replaced the Auxilary Battery the CPS sensor which was first on their list to replace.

I really don't want to spend thousands of dollars with the stealership so please what would be your suggestions to check or replace next. Thanks guys!

Help me get back on the road

 

Do not use a aftermarket cps.

 

Why not aftermarket CPS? I waited till it cools off and still doesn't start after cranking. Tomorrow I'm planning on putting oem CPS back in and see if it starts at least for a little bit. I also did a battery draw test and it was showing me 7.0 to 8.3 when the car was completely off. I figured it was the trunk maybe open since the battery is in the back so I ran a screwdriver to kind of simulate the trunk closing and tricking the car that the trunk is closed and still had the same reading. Therefore something is definitely draining the battery. I'm really lost now, as I thought it could really be the CPS. Any help would be appreciated.

 

When I installed the aftermarket CPS car would crank but wouldn't start, I installed the original CPS back and the car starts with this bunch of messages.
I included the video of what I see now in my dashboard.

https://www.youtube.com/watch?v=NbBDGxVq1D4

 

chances are is none of the problems listed by the dealer. ur most likely cause is the battery control module in the trunk. it controls the battery voltage to the main and aux battery. those go bad all the time on 211s. just replaced one for the same issue on an 05 e55


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alternator...

 

the alternator has absolutely zero to do with starting a vehicle. ALL starting is done from battery power. now ONCE the vehicle is running. and IF the alternator is bad then the vehicle will only run on battery power til the battery is dead..thus having the car die. but having a good, bad, or no alternator will not keep the vehicle from starting.


Posted from Mbworld.org App for Android

 

Did you figure what it was I'm having the same problem right now as we speak I just replaced my VR After leaving me stranded on the road and it needed it the old VR was bad !! but now after i finsih installing it I can't get the car to start I jumped the car up for awhile to charged the battery and nothing it tries to start but it doesn't 😩 helpppp

 

I'm on a similar situation. However my car starts Ok. I just can pass 3K revolutions. I'm going to replace the CAS with an original one, because MB didn't like the aftermarket (sent a P0355 code, Bad CAS).


I'm also looking at the "Aux Batt Sensor" and last (Most expensive) Battery control unit in the trunk.


FYI

 

well car is still down and its my dd and still can't get it to start I Charged up the battery and its good I checked for codes in case my cps or anything but shows me nothing I checked my fuel pumps both of them seem to be working and at this point idk what else it could be I'm so lost 😫 I checked every forum and can't find an answer

 

Are you getting spark at the plugs? If so, I suggest you take the CPS out, inspect it, clean it and try again. If that doesn't work, you need to take to the MB scanner


FYI I tried to use an aftermarket CPS from autozone, new, somehow It got a little crack in the magnet end and of course throw check engine and the P0355 code. I cleaned the original one (some oil around and dust..), and it works Ok. Of course I'm going to replace it anyhow.
I anyhow bring the car to a MB authorized mechanic and He's checking everything with the scanner (voltage, coils, fuel pressure, codes, etc.)
For the scanner he's charge $60-100 depending on the test, so that's not so bad.
I'll post the info once I get it.

 

Okay yea I'm gonna do that this weekend and wow I didn't know that I scan it with obd2 scanner I have and showed no codes but I didn't know there's a specific one for Mercedes Benz ?? thanks alot man lmk what issue yours have. ?

 

I was driving my one on the highway around 50mph and start dying, pressed the gas and went off. Crank it and didn't start, no engine code or ck engine light. Wait a while and the it start. Same thing happen a few times.


On idle can't pass 3K revolution?? That's why I took to the MB mechanic for scanning. Tomorrow I'm going to see the him, I'll post what he find it out.

 

I noticed on the youtube video that you have the "Check Engine" line on. SO you have a storage code. If so, Use the OBDII scanner to read those codes. I'm suspecting your CPS is bad.

 

Following up, the mechanic read a few codes related to replacing the alternator, ABS system and EPS. He said the ABS module is bad, but as far as I know it's been working ok. The replacement estimated is $2K . So I'll have to wait.
He did changed the spark plugs. Wow I didn't know these cars have 16 sparks!
FYI
Car is being working ok so far.