Really appreciate you mentioning that. I figured it was added because my 240d didn't have one originally. (?) I'll go do some more digging, but it seemed like that is what I have to work with.

I do have a red wire, but I was under the impression that was the switched power.

I really need to go get a multimeter and cut out the guesswork. If I can't find another constant power wire.. would adding an inline fuse to the wire from the battery be a good idea? Definitely looking to do this safely!

Thanks a lot!