BMW Repair: E38 M62, video communications systems, fuse boxes

Question
Thanks Tino for your advanced help. I have a 2001 740i. We have had realy bad rain up here in Washington the last month. I park my car on a slight down hill and water seeped in and onto the nav. Bad seal and i have addressed that. The nav unit does not come on, no light on the unit and the screen wnet blank in the car.  i am assuming it is lost. However, the radio will come on, no screen of course, but will only play for about 2 minutes or so. My question is, if i relpace the nav will this likely cure my radio woes too? or is there something else casuing the radio hickup?

Answer
Hi Lewis,
Your car has a complex setup consisting of the audio/NAV/video/communications systems. But before you raise the white flag, try checking the fuses concerned with most of these items and hope for the best.
Fuse 69 and Fuse 46 (these are the primary fuses)
Fuses 33, 48, 49 & 77 (depending on your car's accessories)
There are 2 locations for the fuse boxes, the front which is in the rear right hand side of the engine compartment (in what is called the E-Box), and the rear which is in the right side of the luggage compartment (behind the trim, and above the battery area).
If any are blown, replace them with fuses of the same rating
and check if your problematical accessories powers up at least or goes in line normally.
Other than replacing fuses, there are no user repairable or replaceable parts in your particular car's current problems.
You have no alternative but to bring it to a dealer for diagnosis. Even they would be hard put to firmly diagnose these problems. This could be a trial and error replacement of presumed bad parts with known good parts kind of thing.
And I doubt if replacing the NAV would cure the radio. But I am not sure.
Try this, turn off the key, remove the cable connectors to the NAV on the left hand side of the rear compartment and see if the radio would work properly (this would probably  answer your question). But before touching the NAV or the radio or any electronic part, ground yourself first by touching a metal part of the body or chassis.
Tino