Engine / Ignition / electrics cut out almost every morning

[pr1ngl3]

This is the oddest fault I have ever come across but happens regular enough to be a worry and hoping someone may be able to shed some light. Almost every morning and only when the car is cold, the ignition or electrics cut out for a millisecond but the engine doesn't. I don't get any errors or EML and no errors when connecting ODB.
The only way I know it is happening is because it causes the steering to pull (almost ripping the wheel out of your hand) as the powered steering stops working. Unless you are specifically paying attention to the COMAND system, you wouldn't even notice the flicker off and on it is that quick.

This only seems to happen in the morning (or the 1st start of the day) when the vehicle is cold and only at low speed, its almost like the auto transmission moves to 3rd gear and 'blip'.
I have had it a couple of times where it comes back to life and starts complaining that the hand (foot) brake is engaged when it isn't, and I have to turn the ignition off and back on to get it to clear.

The only other issue I have is, every now and again it complains that the Aux battery has malfunctioned.

 

[LostKiwi]

Hi and welcome.

 

[pr1ngl3]

Hi and thank you.

I guess I should add that it is a 2015 W212 E250 7G Tronic

 

[Craiglxviii]

This is the oddest fault I have ever come across but happens regular enough to be a worry and hoping someone may be able to shed some light. Almost every morning and only when the car is cold, the ignition or electrics cut out for a millisecond but the engine doesn't. I don't get any errors or EML and no errors when connecting ODB.
The only way I know it is happening is because it causes the steering to pull (almost ripping the wheel out of your hand) as the powered steering stops working. Unless you are specifically paying attention to the COMAND system, you wouldn't even notice the flicker off and on it is that quick.

This only seems to happen in the morning (or the 1st start of the day) when the vehicle is cold and only at low speed, its almost like the auto transmission moves to 3rd gear and 'blip'.
I have had it a couple of times where it comes back to life and starts complaining that the hand (foot) brake is engaged when it isn't, and I have to turn the ignition off and back on to get it to clear.

The only other issue I have is, every now and again it complains that the Aux battery has malfunctioned.

It sounds very much almost exactly like the auxiliary/ consumer battery has malfunctioned…

 

[Botus]

I'd like more more info on the "fault" ?

is there dashboard flicker / lighting glitch showing ANY evidence of an electrical issue?
does the engine cut /cough for a split second?
or as you wrote just a snag on the steering wheel?

if its just a snatch of the steering wheel, I don't see how craig's point works... if just the wheel I think its ESP intervention (and I'm guessing its an ABS sensor playing up / dirty)

 

[pr1ngl3]

Hi and thanks for the replies.

To answer Botus...

There isn't a dashboard flicker but the COMAND does flicker but so quickly. (although the dash may flicker so quickly that it doesn't register). There is no drop in music though .
The engine doesn't cut out or splutter at all.
As mentioned with regards to the hand brake, when the above has occurred and it has resulted in the car complaining that the hand brake is still engaged (which has only been about 0.5% of the time), it has also made the audible alarm that accompanies pulling off when the handbrake is still engaged. I know this to not be the case because I do not use the hand brake - it started sticking after they replaced the pads and as such, I just don't bother using it unless parked on a hill.

As mentioned, no errors, lights, or other indication to the cause other than the violent pull on the steering wheel

 

[Botus]

electronically always a nuisance park brake? or a grown up manual one that the user can apply as and when required?

note the modern troublesome ones, use the ABS sensors to work out it should have let go 1m beforehand