W203 Electrical Issues - Help!

[TheCaretaker]

Hi Guys,

Long time lurker, but after 3 reliable years I'm starting to have a few issues.

It's a 2012 C200 Estate, I started it up about a week ago and drove off fine, but then noticed some problems - to following are not working - gauges on the dash (speedo, revs, etc), the LCD panel in the centre is black, indicators not working (although hazards are), windscreen wipers, radio, electric windows, fan, the not-wearing-your-seatbelt alarm, auto headlights.

It all seems to work if you get in and turn the key half way, but once you start the engine, none of it works.

I've check all fuses are good and that's about the limit of my knowledge.

Anyone had anything similar? Any thoughts or suggestions appreciated.

Recently had it serviced, new tyres, front suspension arms, so I'm hoping it's nothing too major/expensive...

Regards,
Kerry

 

[Oldspanners]

How old is your battery?
As an old battery will start the car and it will run but will throw up all sorts of strange problems as the voltage varies.

 

[TheCaretaker]

Sorry, I meant 2002, not 2012!

I've popped it to my local garage, they've had their electrical guy look over it, so I'm assuming they would have checked the battery.

It's not intermittent, it's all just suddenly died.

They have pointed to something to do with the dash, but said they might have to send something away to get it looked at. I'll be speaking to them properly in the morning, didn't have time to get proper details this evening.

 

[mioba]

They have pointed to something to do with the dash,

No shi* Sherlock, haha

Glad it is getting sorted

 

[mersum1es]

Ask them to check front and rear SAMs for water contamination/corrosion...

 

[mattkh]

They have pointed to something to do with the dash, but said they might have to send something away to get it looked at. I'll be speaking to them properly in the morning, didn't have time to get proper details this evening.

My money is on the ignition switch itself.

 

[Droverunner]

Their electrical guy may have looked it over but I wonder if they have a good Mercedes specific code reader?

 

[Oldspanners]

Sorry, I meant 2002, not 2012!

I've popped it to my local garage, they've had their electrical guy look over it, so I'm assuming they would have checked the battery.

It's not intermittent, it's all just suddenly died.

They have pointed to something to do with the dash, but said they might have to send something away to get it looked at. I'll be speaking to them properly in the morning, didn't have time to get proper details this evening.

Regardless have a look at the battery, the date will be stamped on one of the battery terminals also check if it's the correct AH rating and it's a reliable mark.

 

[Droverunner]

>>>Regardless have a look at the battery

Agreed. My Viano came with an old battery that started the vehicle fine but with a voltage that gave some glitches which went when I bought a new one.

 

[TheCaretaker]

Been away for a bit so haven't made any progress so far.

The garage sent the 'clocks' away and got them fixed, their electrician said everything pointed towards them. On the plus side, the LED display has never looked so good, on the downside it didn't fix the problem.

They then said they thought it was the ignition switch so got a second hand one, but couldn't use it or get it to work, something to do with coding it? Can anyone agreed any light on that?

Seems to me that it could possibly be something ignition/key related, especially seeing as everything works fine at half a turn, then stops once it's fully turned.

They suggested taking it to a Mercedes specialist to scan, so I'm assuming they don't have a Mercedes specific code reader. Would that be expensive?

Will check the battery tomorrow as well.

I was hoping for a cheap fix, not really willing to keep paying for different things until the problem is solved, not sure how much that would end up costing. The car was cheap and it's been reliable for the last 3 years, but it might be time to reluctantly move on.

 

[Droverunner]

>>>They suggested taking it to a Mercedes specialist to scan

Really until this is done you haven't even scratched the surface of a proper diagnosis.

 

[TheCaretaker]

I have a Mercedes specialist nearby, so that's an option. Would a scan pinpoint the problem, or is it more of an indicator of where to investigate? So it still could potentially go on to cost a lot more.

 

[Droverunner]

A scan can sometimes go straight to the issue but other times nothing is shown but that will at least tell the specialist what they're not looking for if that makes sense. Even a £100ish DIY code reader as long as it's Mercedes specific is loads better than not knowing where to start.

In truth it's not really possible to fault find much at all on modern cars without diagnostics. Add to that a Mercedes specialist is going to have far more idea than the average garage.

 

[AnthonyUK]

They then said they thought it was the ignition switch so got a second hand one, but couldn't use it or get it to work, something to do with coding it? Can anyone agreed any light on that?

What a bunch of clowns.

 

[TheCaretaker]

What a bunch of clowns.

Yes, I'm seeing that now They have always been fine with mechanical stuff, obviously not so much with the electrical side of things.

Going to try to get it booked in and scanned this week.

Anyone shed any light on what they meant by not being able to get the ignition switch replaced?

 

[Droverunner]

We are lucky to have two quite old school small garages in our village. Both do fair and honest MOTs and both will be fine for an all filters service or discs/pads etc. Both would go that extra mile to try and help. But I wouldn't take them a Mercedes or similar complex modern car with electrical issues.

Good luck with the folks that can scan yours... I hope it will bring a decent result.

 

[AnthonyUK]

Anyone shed any light on what they meant by not being able to get the ignition switch replaced?

It (the EIS) is the core of the security for your car. Although the 203 is not overly complicated, it is linked to the key and ECU to 'unlock' the car and start it.
To replace one requires that all those parts are able to share the correct crypto codes to work correctly together, so, if you replace the EIS then it needs to be coded which requires MB level equipment.

There are some very resourceful people around though.

The ultimate Mercedes EIS repair guide

1

mhhauto.com

 

[TheCaretaker]

Ok, the above makes sense. The garage I've been using, while very helpful, are clearly not cut out for the this.

Based on the above, the ignition switch they got could still be used in the right hands then?

Anyway, just speculating, it's booked it in for a scan tomorrow with a specialist, will have to wait and see. Getting a bit awkward without wipers now that the weather is turning. If I can't find a quick fix, might just have to replace it.

 

[TheCaretaker]

I'm giving up! Latest garage have said it looks like the front SAM board but they can't do this and it would need to go to Mercedes to do it.

Whether they just don't want to do it or whatever, I'm throwing in the towel. I don't have enough time to mess around taking it to multiple garages and in the condition that it is in, it's definitely not worth a trip to the dealership.

Shame, been rock solid for the last 3 years, but it's time to move on I think.

 

[Droverunner]

I thought a SAM unit replacement (sometimes even repair) was a DIY job if experienced... surely a decent specialist should be able to do. Hopefully someone will know for sure.

But re getting shot because you're fed up.... I had a newly purchased used Volvo bought for my daughter which suffered exactly the same type of issues due to their version of a SAM unit. It let me down once when taking it for a test run and then soon after let her down twice in two days in her home area on the way to work. As much as anything as she was 100mls away so I couldn't easily assist I managed to get the garage we'd bought it from to give a full refund so we got it transported to them. They are decent guys and reported their auto-electrician was able to remove corrosion internally on the unit and it was fine afterwards.

So I do understand when it gets to a point of tipping over to getting something else.