Mercedes S350 W221 - 2012 - Digital Speedo Screen goes blank on Start up

[Rich2166]

My car is a Mercedes S350 Bluetec W221 - 2012

The issue I have been having is on a number of occasions when I go to switch on the ignition the digital Speedo dash illuminates exactly as it should, however when I go to start the car a few lines show on the display then the Speed Cluster goes Blank, but then after roughly 10 seconds the screens comes back on

Once the screen comes back on it stays on and there is no more issues, until the ignition is switched off and the process repeats, but it does not happen every time.


I would appreciate any Member suggestions what the issue could be

Many Thanks

 

[Botus]

sounds wrong, mines never done that, almost as if it reboots….

what state is the battery, can you charge fully and see if it behaves....? you can top up an AGM with distilled water they recover and will give another 5 years service and outlast its Merc original replacement. The screw top lids are a bugger to get off

 

[alexanderfoti]

+1, BCM switches to rear battery half a second after start. If rear battery is flat, it will use front battery to power central locking etc

 

[alexanderfoti]

Although 2012 is facelift so should only have one battery.

 

[Rich2166]

Thank you AMF & Botus for your replies,

My car has two batteries one in the front and the other behind the rear seat.
Also Yesterday I replaced my Auxiliary battery with a brand new battery as I had been getting Auxiliary battery malfunction message on my dash, I’m not sure whether this has Anything to do with it

 

[alexanderfoti]

Thank you AMF & Botus for your replies,

My car has two batteries one in the front and the other behind the rear seat.
Also Yesterday I replaced my Auxiliary battery with a brand new battery as I had been getting Auxiliary battery malfunction message on my dash, I’m not sure whether this has Anything to do with it

I would be checking the state of the one behind the rear seat next then.

 

[Rich2166]

I would be checking the state of the one behind the rear seat next then.

The Auxiliary Battery was behind the rear seats, that was the one I replaced.

 

[Botus]

two batteries in 2012 sounds odd... 2005 to 2007 had a 25kg one in the boot and a 15kg one under the bonnet, they ditched that after 2007/8

unless u have a special one with loads of toys or something ???

on the early ones with the rear battery, the box of tricks above right of that battery is the box of tricks that works out how the car is going to charge and use both batteries

 

[Rich2166]

It’s just a standard S350 Bluetec W221 - 2012

It has the big battery on the passenger side under the bonnet and the tiny Auxillary
Battery behind the rear seat panel.

Also I took a video of what was happening to my Speedo which I’ve included

 

[alexanderfoti]

Have a look at your big battery, its voltage is dropping too low during start-up, the alternator does not start charging until the engine has been running for 4-5 seconds.

 

[Rich2166]

Thanks AMF, I did think of that, let’s hope my message that was coming up on my dash for a Auxiliary Battery Malfunction, was actually my main battery not my auxiliary Battery, otherwise I’ve had both Batteries need replacing at the same time

 

[alexanderfoti]

It could be both, the aux battery will be put under more stress with the main one failing. You can prove the point by jump starting to the main battery. Does it do it if you start it after stopping after a long drive?

 

[Rich2166]

It could be both, the aux battery will be put under more stress with the main one failing. You can prove the point by jump starting to the main battery. Does it do it if you start it after stopping after a long drive?

Thanks, Can I ask what you mean by jump starting to the main battery?

The speedo display only does what the video shows on the first start of a new day, ie once it has been parked up over night, and I come out in the morning to start it up, the screen goes blanks it comes back on but doesn’t do it again, especially after a short drive

 

[Blobcat]

Thanks, Can I ask what you mean by jump starting to the main battery?

The speedo display only does what the video shows on the first start of a new day, ie once it has been parked up over night, and I come out in the morning to start it up, the screen goes blanks it comes back on but doesn’t do it again, especially after a short drive

Sounds very much like a low voltage issue.
Jumping the main battery, is connecting another battery to yours when you start it.

 

[kennymerc]

My car is a Mercedes S350 Bluetec W221 - 2012

The issue I have been having is on a number of occasions when I go to switch on the ignition the digital Speedo dash illuminates exactly as it should, however when I go to start the car a few lines show on the display then the Speed Cluster goes Blank, but then after roughly 10 seconds the screens comes back on

Once the screen comes back on it stays on and there is no more issues, until the ignition is switched off and the process repeats, but it does not happen every time.


I would appreciate any Member suggestions what the issue could be

Many Thanks

Hi there, I had exactly the same problem with my 2012 w221 350 blue tec, it is the main battery under the bonnet, 100 %.

 

[Rich2166]

Sounds very much like a low voltage issue.
Jumping the main battery, is connecting another battery to yours when you start it.

I don’t unfortunately have a spare main battery to jump from, out of interest if I drive my car to a battery shop could I get them to put a voltage meter across the main battery and would this tell me if the battery was working as it should?

Thanks

 

[Blobcat]

I don’t unfortunately have a spare main battery to jump from, out of interest if I drive my car to a battery shop could I get them to put a voltage meter across the main battery and would this tell me if the battery was working as it should?

Thanks

Buy a cheap digital voltmeter 12.6v with engine off and >14.5v when charging is what you’re looking for.
Do you have another car you could jump from or a friendly neighbour?

 

[Rich2166]

Thanks, Yes I can do that, when you connect the jump leads from the second car to the main battery,
does the second car have to be running or just the leads connected?

Many Thanks

 

[Rich2166]

Hi there, I had exactly the same problem with my 2012 w221 350 blue tec, it is the main battery under the bonnet, 100 %.

Many Thanks Kenny,

I’ve only just replaced the Auxiliary Battery on Friday, so having to replace the main Battery as well is something
I really could of done without. Did you end up having to replace your Auxiliary Battery at the same time?

With the Auxiliary Battery I was advised to only fit a Genuine Mercedes one due to it being Voltage critical
however I wonder if it’s the same with the main battery as well, or whether I could fit an alternative brand?

 

[Blobcat]

Thanks, Yes I can do that, when you connect the jump leads from the second car to the main battery,
does the second car have to be running or just the leads connected?

Many Thanks

I generally connect with the other car idling, if their battery is in good condition you can connect with their engine off