So I've been searching through this forum and Google but I couldnt sem to find anything to my issue. My '05 525 suddenly wont start. I had driven it over the weekend, then it rained a couple days, and when I went to try and drive it again it wouldnt start and there is a transmission fault on the iDrive display. It won't even crank, when I try to start it nothing happens.

I tried connecting a scanner to the OBD port but it kept erroring saying it cant connect to the tranmission, same with my Carly adapter it never connects or just freezes but no errors pop up.

I've read that the MPM in the trunk might be bad, but I moved that out of that well years ago. I also checked for water in the carpets, and everything was dry. I'm concerned its more serious (and expensive). Everything else in the car works, it just wont start. I checked fuses and they all are fine.

Any ideas?? I'm desperate at this point. Im just glad this happened when I was home. I had driven it 3 hours away the day before it started raining.

 

You checked the IVM and connectors in that box. Pay attention to pin 15. Probably the whole X6009 connector is bad or maybe x6021. Youre issue is definitely electrical from what I'm reading. Just need to find the bad location. Also check the X13783 connection. Its under the driver kick panel.