Electrical Issue?

[Lorraine Wyllie]

I have had my C220 for 3 years now it's an early 2012 model and normally a dream to drive. I've had an intermittent issue on start-up where all of the safety/warning systems show a fault. Vehicle locks in park with no function on wipers, indicators, radio, internal lights. Engine fan is running at start-up despite the engine being cold.
Our local garage had the vehicle for 2 weeks, tested all of the control modules and emu and found no faults. They put it back together and it has run perfectly until today when the same fault has reared its ugly head. Has anyone had this issue or have any ideas what's causing the fault?

 

[malcolm E53 AMG]

Welcome!

Is the car still fittedwith the original battery, if so that’s a good place to start, a failing battery can throw up all sorts of electrical gremlins especially at this time of year and if you do short runs?

Your car may also have a smaller convenience battery which runs some of functions on the car so again this may be failing

 

[LostKiwi]

Agreed. This sounds very much like a low voltage issue

 

[AMGeed]

Agreed again

Low voltage is a big problem on most MB models.
Have the battery checked under load (Halfords do it for free)

 

[Lorraine Wyllie]

I think it might be the original bettery - I do 100 mile round trip to and from work, mostly motorway so it shouldn't be the short journeys thing. I'll have the battery checked to rule that out - thanks for the advice. Any pointer to where the 2nd battery might be?

Welcome!

Is the car still fittedwith the original battery, if so that’s a good place to start, a failing battery can throw up all sorts of electrical gremlins especially at this time of year and if you do short runs?

Your car may also have a smaller convenience battery which runs some of functions on the car so again this may be failing

Welcome!

Is the car still fittedwith the original battery, if so that’s a good place to start, a failing battery can throw up all sorts of electrical gremlins especially at this time of year and if you do short runs?

Your car may also have a smaller convenience battery which runs some of functions on the car so again this may be failing

 

[malcolm E53 AMG]

It may not have a second battery some do and some don’t, my e class does. At seven years old I’d definitely change the battery as LK mentioned Merc’s don’t like low voltage and can develop spurious faults. My car is ready for a new battery at seven years old which is good service for a car battery. Buy Varta or Bosch batteries the best have a 5 year guarantee

 

[Lorraine Wyllie]

Hi guys. Thanks for your input. I have replaced both batteries today with Bosch replacements but still seeing the same faults. Any other pointers to what it might be?

 

[Lorraine Wyllie]

Welcome!

Is the car still fittedwith the original battery, if so that’s a good place to start, a failing battery can throw up all sorts of electrical gremlins especially at this time of year and if you do short runs?

Your car may also have a smaller convenience battery which runs some of functions on the car so again this may be failing

I've replaced both batteries, but still seeing the same fault. All the safety systems seem to be malfunctioning - any other ideas what it might be?

 

[malcolm E53 AMG]

This might help, seems it might be the pre-fuse box

https://forums.mbclub.co.uk/threads...es-engine-starts-but-wont-engage-gear.225429/

 

[Wighty]

I have had my C220 for 3 years now it's an early 2012 model and normally a dream to drive. I've had an intermittent issue on start-up where all of the safety/warning systems show a fault. Vehicle locks in park with no function on wipers, indicators, radio, internal lights. Engine fan is running at start-up despite the engine being cold.
Our local garage had the vehicle for 2 weeks, tested all of the control modules and emu and found no faults. They put it back together and it has run perfectly until today when the same fault has reared its ugly head. Has anyone had this issue or have any ideas what's causing the fault?

When you say your local garage , are they using Mercedes diagnostic equipment such as "Star" , because without this they have less chance of identifying the problem , and you will keep buying parts such as 2 batteries .

 

[Lorraine Wyllie]

When you say your local garage , are they using Mercedes diagnostic equipment such as "Star" , because without this they have less chance of identifying the problem , and you will keep buying parts such as 2 batteries .

Hi Wighty,
Local garage I don't believe have "star" diagnostics, but I would expect that from the Mercedes specialist I'm using this time. Thanks for your advice - I'll be sure to ask the right questions this time around.

 

[Lorraine Wyllie]

This might help, seems it might be the pre-fuse box

https://forums.mbclub.co.uk/threads...es-engine-starts-but-wont-engage-gear.225429/

This is exactly the issue I'm having - I've stored the details to be discussed today with the garage. Thanks for your help - you guys are terrific.