kasper

Any ideas on my problem?

At cold start everything is fine, after About 20 mins errors pop up.
Esp not available, tyre pressure monitoring, few mins later faulty display, brake wear... Few mins later battery/alternator.

Voltage readings
After cold start charging voltage shows 14.2
Than slowely drops, around 13.3 errors start comming
and keeps dropping
Already changed voltage regulator...

Help much appreciated

RenC55AMG

I'd have to say alternator off the top of my head.

to1988

Hi!

Try a new battery.

Dollos

My money is also most definately on the Battery...

denpa

I was at my mercedes mechanic and they had an c55 that was there for 1 and a half month. I just had to ask what was wrong with it.
It had similar symptoms what OP wrote. It turned out to be a (major) glitch in the electrical system.
I did not clarify if this occured direct or after a while from start up.
Otherwise i agree with previous anwsers.

kasper

thanks so far!

Can it still be the battery if I measure about the same voltage drop at the alternator?

Khan 55

Have you tried disconnecting the battery and reconnecting it after say 10mins or so. Remember to always remove negative terminal first and then positive and reconnecting is vice versa of the above. I would wait a while with both terminals off. Check the battery voltage immediately after disconnecting then check the reading 10mins later.
If you a tech guy you can go ahead and do the battery test with the hydrometer. Make sure if its a maintenance battery that your fluid level is okay between each plate.
Hopefully the above helps you.
If you are testing the efficiency of your alternator I would check apart from idle charging, at a higher rpm after engine warms up and then put all the consumers on and see what it reads at idle and at 1500-1800rpm.

kasper

Thanks so far!
Here are my readings...

Battery:
immediately after disconnecting it's 12.20v
after about 10 minutes it's 12.23v
connected it's 12.13v

efficiency of alternator:
after cold start: idle 14.2v
after about 15 minutes of idling with no extra consumers: idle 13.7v/1800rpms 13.7v
now with all consumers on: idle up and down from 12.7-13.0v/1800 rpms 13.5v

swedepat

A fully charged leadackumulator shoud read 12.62 unloaded.
A fresh battery in car. decent charged should read about 12.3-12.5v

Try to charge battery fully and then look for altering in behaviour, then you might get a lead to the problem.
and then charge it again unconnected to car ofcourse and leave it a couple of hours, if there´s voltagedrop at about 0.1-0.15v the battery shows that it isn´t good.

Otherwise, front sam module might be bad.

kasper

Thanks!
Gonna try that.

C230 Mulac

You really need a STAR diagnostic hooked up to read the codes. This could be so many different things...

When the errors pop up, are you driving or parked? If driving, does it go into limp mode (stay in whatever gear you are in and not shift)? When parked, does your shifter get stuck in park?

If you can drive, does your speedo appear to be working properly? These codes can come up if a wheel speed sensor is bad.

Could also be a lot of other things too.

kasper

Errors come both driving and parked...
And yes it goes into limp mode and gets stuck in park when parked.
Once 'faulty display' shows, it goes into limp mode with all the problems including non working speedo!

C230 Mulac

It could very well be the ABS module, but it could also be something like the transmission conductor plate on top of valve body. You won't know unless you have the STAR hooked up. That's exactly what was going on to me and when I diagnosed it via STAR, the code specifically told me that the ABS/ESP module was defective and the corrective action was to replace it.

kasper

The car has been hooked up on STAR lately,
but at that moment the car was not in limp mode and errors were not showing in my display....
There were about six pages of stored faults, but after clean up no faults at all.
Should it be hooked on STAR when the cars is in limp mode?

Khan 55

Yes even though I don't see how that should differ as if the limp mode fault code came up, it would then be stored not so? However if the problem is active atleast you know at what state it becomes active and can better diagnose it. So connect it to a Star when its limp.