Big Bob - I think you are right. The first one seems to be for the assist function, I put the one for the Nav.

They both fit snugly in the same place and I can't get any decent answers out of the dealer on how these things are done on an original install. Neither does there seem to be much inclination from people on the E53 forum to have a look at their install as I found when I asked a question about something else.

I guess I will simply have tackle a nearby neighbour one day who seems to have the same car, not sure if it has the same set-up though..... I looked at a 2005 4.4i and did not get any wiser.

I even emailed a company in Germany that sells complete retrofit kits (sans the components that is) and even they could not answer how to connect the red Nav connector when installing a replacement harness rather than the retrofit harness.

BMW's design for the car is way too complex and the parts documentation is appalling.

The equipment is all working fine, life is too short and I have other stuff to do.