??? Hard to tell what that photo is, but looks like a body ground gone bad?
Filippo
The E90 has 2 connections on the positive side of the battery inside the battery box. They go through into the wheel well and then run along the entire car, up into the engine bay.
The thick wire is for the alternator and starter and the thinner wire goes to the water pump fuse.
In my case the plastic casing covering the feed line for the waterpump inside the wheel well had cracked.
Combine that with time and salt, humidity, since its located inside the wheel well behind the inner liner, this caused heavy corrosion..
It was green when i got there and basicly broke loose when i just touched it..
So i willing to bet quite alot of money on that this must have been the issue.
That could also explain the fluctuating voltage that i saw when i measured the voltage in the engine bay when the wp tried to run. I also measured the voltage where the wp feed line connects and that was constantly 12,8v.
This caused me to pull the entire bottom plastic and also DME with entire DME box to follow the wp feed line from the engine bay, all the way to the battery.
Finally i found the corroded connector when i pulled of the right rear wheel and the inner liner..