[EwenMac]

hi does anyone know what the two fibre optic cables are for on the connector of the CD73 "Professional" radio, i don't have tweeters but i do have the factory sub woofers under the front seats.

why i ask is that im wanting to upgrade the system to a double din but when i remove the radio connector and then re connect it i hear a noise from the HVAC unit, and im wondering what the interconnection is. ive seen a bridge connector

is this something to do with the "MOST" system ??

truly lost at this point

my existing radio is non functioning, i tried replacing the LCD screen and have somehow killed it, i used to work in electronics so i have half an idea what im doing, but managed fail this task

thanks

[ptpending]

getting the used cd73 from ebay or junkyard is cheapest option this days
the green fibers are MOST loop, connecting telephone modules, cd-changer, dab or sirius modules or top-hifi amp to headunit
if you don't have any of these options then you may not bother with it

[ctuna]

It would help if you knew something about the Most Loop .
The Radio is the Interface or Server between the Most Loop and the modules that do Bluetooth , Sos , Sat Radio and Amplifier if you have a Logic 7 amp.
They are Searial loop so any one module broken break's the chain.
The Head unit is programmed to look for and run the options that are installed.
This means if you get another head unit you probably will have to program it to your installed options
See the coding sub forum .

Logic 7
https://www.e90post.com/forums/showthread.php?t=1056432
https://www.bavlogic.com/?p=3729
https://www.bavlogic.com/?tag=loop
http://www.bmwlogicseven.com/?p=3837
http://www.bmwgm5.com/
https://www.e90post.com/forums/showt...5#post24455335
http://www.e90post.com/forums/attach...2&d=1260829447
http://www.google.fr/url?sa=t&rct=j&...slMu2A&cad=rjt
https://www.bmwgm5.com/Logic7_E90_91_92_93.htm
http://www.bimmerfest.com/forums/sho...d.php?t=982666

http://www.e90post.com/forums/attach...1&d=1209780605
Most
http://www.e90post.com/forums/showthread.php?t=727663
http://www.e90post.com/forums/showthread.php?t=347222
https://www.google.com/search?q=BMW+...VCkMqy2aCK09M:
http://www.1addicts.com/forums/showt...php?p=19256760
https://www.teacremotes.com/bmwgm5/
Diagnostic Manuals Inpa/Ista D
https://bimmerprofs.com/diagnostics-inpa-part-1/
https://www.google.com/url?sa=t&rct=...7x8H3pN8h1fMuF
https://carmod.ru/files/icom/istad_en.pdf
https://www.e90post.com/forums/showthread.php?t=1681573
https://www.bimmerforums.com/forum/s...-P-actually-do
primary links
https://www.bimmerfest.com/forums/at...9&d=1539905743
https://www.e90post.com/forums/showthread.php?t=1681573
https://www.bimmerfest.com/forums/at...1&d=1590283589
https://www.nathansbmwworkshop.com/b...or-dean-videos

[EwenMac]

thanks Ctuna, ive read through some of your links and also googled BMW "MOST" for myself, to try and get an understanding of what im messing with

please correct me but it seems the MOST system is just related to the sound system and associated components.

as i don't have (excluding the phone module, which i don't use) any it seems to me that i can disconnect the OEM unit and install what ever i like, excepting of course that there is an issue with backup power for memory,

should i get a bridging link to link the incoming to the out going fibre optic cables??
or can i just ignore it, as i don't have any of the associated modules

as the car is 17 years old im not sure that the comments ive read about BMW not being able to update firmware without the OEM radio in place applies.

i look forward to your obviously educated response

and thank you for your input

[ctuna]

Replacing the Head Unit is a can of worms when going to aftermarket.
The Most Bus system runs SOS , Sat Radio , USB , Bluetooth .PDC (chimes)
and the Logic 7 amp if you have one.
You may not have those installed and in Europe I hear there cars that do not have a Most bus from the factory and just use an analog interface for Entertainment systems.

When you remove it you will get and SOS error at minimum and the Logic 7 amp will be useless without a analog to Most converter.

BMW may refuse to service your car if you need them to .

Car Alarms and dongs come through the stereo some aftermarket headunits support this some do not.
This can be fixed with something like a connects 2 harness if the head unit does not support the gongs
I don't know what they put in the Cars in Australia you may have to find local help on that .

You are ripping out the most bus if you change the head unit all the modules are dead but the car is still programmed to look
for them . The most obvious the SOS function which is the most common thing people program out using NCSexpert as
described in the coding sub forum. No More Oem Head Unit = no more Most Bus .

There is no connection to the Heating / Cooling system at all through a Pro Radio or Idrive that I am aware of.

[EwenMac]

thanks for your help

ill post my results, fingers crossed