Electrical fault 320 cdi

[jonnyswamp]

I have a strange electrical fault on my 57 plate CLK 320 CDI
On first (and second i think) click of key everything works fine, as in indicators, radio, windows, heater blower, temp and fuel gauge
However, after crank and the engine starting everything fails to work and after a few seconds the radiator fan kicks in at full speed
This doesn't happen all the time and the car is still driveable and doesn't go into limp mode when at fault
when it starts and drives as normal, the engine management light stays on
I don't know if the light is on when it's at fault as I haven't driven it (mainly driven by my wife)
If it goes to fault, sometimes turning off, removing the key then trying again cures it, albeit temporary
Any clue's?
Thanks for reading, all replies welcome, even insults

 

[zipdip]

Well I am sure one of resident electrical geniuses will answer soon,but have you had to change the battery or the battery been disconnected for any reason,that can play havoc with the ecg,also it never hurts to check earths,have you got even a cheap diagnostic reader some only cost £10 on ebay but plugged in it would help to find out what is putting the engine management light on the dash,as I say the experts will be along soon.

 

[jonnyswamp]

The problem only materialised 3 days ago, last week had a couple of tyres replaced and a brake light bulb changed at a mates garage
I'll get it back to him next week to plug it in, hopefully something will be at fault and show up
I get intermittent faults in my game (heating eng) and know how frustrating they can be

 

[zipdip]

Well just maybe you have a wrong value bulb in the back,I know it sounds crazy but these can bus electrical systems can be very weird ,it might be worth a try as a bulb is very cheap,buy the right one and you have lost nothing if the one in the car is correct you will have a spare

 

[jonnyswamp]

I did wonder about the bulb, but faults didn't materialise straight away
I'll try the bulb change first though
Cheers

 

[jonnyswamp]

Update, so it appears to be an EIS problem (according to my mate who owns his own garage, but isn't a MB specialist)
Does anyone know of a firm I can send it to to repair?
It's a W209 model, CDI 320 CLK 57 plate
This diagnosis was done by a friend of my mate over the phone, does it sound right