Could be this below your carpet mate BMW E39

 

i posted about this fault and am glad to say i got to fix the problem, it was the power distribution box below drivers seat which was in a pool of water. not easy to access when electric seat doesnt move so had to cut carpet etc to access it, then had to remove it and dry it out and repair 4 broken/corroded positive wire and then reassemble everything and all lights worked and car started.
also traced water leak to osr door seal and repaired that so car has been starting and driving great since then.
however in last few days car will turn over but not start most times and then when it starts it cuts out straight away, it has occasionally run for five minutes but then when i switch it off it wont start again.
also, i cannot read any fault codes on it as i cant access the engine ecu with code reader but can access abs, airbag etc.
i have rechecked distribution board and all connections etc seem to be fine, just wondering if anyone would have any idea what it could be, or whether it is something completely different..

 

Under the dash on the drivers side there is a pocket and if you look in the top of it you will find an Port to plug in a scanner and you can then read the codes' from there. If you had not said about the water problem in the box i would have checked the crank and cam sensor. I think it prob has something to do with the water getting onto the electrics and caused a short somewhere in the car. Code read the faults and see what you get mate.

 

Thanks for the reply., I have found the obd socket and used scanner but it won't read any codes on engine ecu but I can read codes on airbag, abs system while connected, so it's us if there is no power to ecu or maybe ecu itself, but strange how it will start up sometimes..
Maybe need totry a cranksensor, do you know where it is located and how much...?

 

fuse or relay or ignition switch also check battery leads

 

Have fitted new ignition switch, what/where fuse or Relay could it be..?

 

The flood you had could cause long term issues. IMHO don't change any more parts and take it to a professional. Fuseboxes that have been under water invariably end up having to be replaced, and can present wierd and wonderful faults.

 

Thanks, that's interesting about the fuse box, any idea what a new one would cost.
Between myself and small local garage I have tried three different scanners on car and none will connect to engine or gearbox ecu but abs/ body ecu etc all can be seen.
Just wonder if any relay or fuse would be at fault, I have checked fuses and all ok but relays I am not sure about, would like to be able to check if any faults present before fitting a new fuse box or having to transport it 110 miles to BMW dealer
Any help much appreciated..

 

Does anyone know if any wiring diagrams I can look at to check wiring between Siemens ms43 ecu and obd plug or if any earth or live point is interconnected to both, i can't help think nonstart must be to do with ecu not working...!
If I can get it so u can read fault codes I hopefully will be able to start it as well or at least see what codes stored.