I purchased a secondhand 545i a month ago and I haven’t been able to drive it due to it randomly shutting off. When it does the car doesn’t even attempt to start. Then randomly I’ll attempt to start it and it turns over right away. I think it’s may be the battery cable, is it possible to use the 2006 e60 battery cable on a 2005?

 

BUMP. I’m having the same issue

 

did you find what the issue was?

 

If the car is completely dead without any signs of power (electricaI) I would guess ttowards battery or power supply,
but if I has some juice I would look at integrated supply module

 

after all the research I’ve done I think my issue is the integrated supply module because of the symptoms and also because my car wasn’t starting and hitting the ism box makes it crank and start and I did that 2 times today both times it worked so I’m hoping that’s my issue

 

Can you see visual water corrosion indications in and around the box?

 

yes

edit. After looking inside the box I can tell it’s been wet before so I’m gonna replace this

 

Good work confirming the BMW eBox design flaw.

To run an experiment, a few years ago I put a clear sheet of plastic across the top of the eBox (and draped it over the box a little).

The clear plastic on top of the eBox discolors in brownish spots as water hits the top of the box. Its easy to see the water engineering.

If you are standing at the radiator looking towards the firewall, I can see water is designed to naturally drip at 10 o'clock on top of the box.