Hi Jamie,

We have one of these and it had to have a parking brake unit/module the other week. Ours is under extended warranty so it was covered with a small excess at BMW.

They are quite expensive, I did find something on internet about removing unit,splitting it and finding water/corrosion on main terminal and that was my option if they bulked on the warranty. I think I saved the link on work computer I will check and post later.

Cheers
Matt