Tonyb4889

Hello all hope someone can help.

About 2 months ago I went to start my Mercedes c class 2011 plate and on my dash it come up two errors.

Run Flats inoperable and ESP inoperable.

So I turned the car back off waited a minute and it was fine. A few weeks later the car did this again so I turned it off then I was unable to start at all so called the AA. They plugged in to ECU cleared a few minor errors and still struggled to get it to start.

All of a sudden it just come to life and it was fine for another couple weeks then it happened again but instead of turning it off to reset these errors I carried on driving as had to get to work. Mid journey the command unit closed down and I had a low battery error on the dash.

I got the car to work and the battery was flat. I took the battery out and put it on charge for a day in the workshop as I I am also a mechanic/electrician but for the trains, connected it to car and it just would not start.

Called AA out and fuse 7 the fuse that sends the voltage to the contact on starter had blown. So we disconnected the wire going to the contact from the back of front fuse box, and removed the relay that switched the voltage to the contact. Put a fuse in and it did not pop but the second the relay went in the fuse popped.

Tested the relay that was all good, even unplugged the ECU as the coil of relay goes there, ground switch I guess, but the fuse still blew.

I suspect the front SAM is faulty but can all these errors and the battery drain all be linked to the SAM unit or have I got separate problems here?

Any help would be great
Thanks