Hi Everyone I am sorry to  bring this up again however I found a link and it answers lots of my questions and not all. So here goes.

I have a 645 Ci on a 2004 plate. I brought the car very impulsive as it was a car I have dreamed of owning. In turn recently I have had a mute symoble come on my Lower screen on the I drive display and no sound. No chimes nothing. No Music. I go to have radio station and it jumps right back to the original station but again no sound. It had an after marked Cd Changer futted not by my self I'll add and has had a display warning head until not programmed correctly however has worked for over a year liek this and played CDs from the changer. I have order a Male and femail fiberoptic loop as I was told I could work my way through the module. My AMP logic 7 has power and lights up with in the amp and has the red light from the fiberoptic cable. My phone however will not pair am lead to believe it could be my bluetooth that's bad. Is it a case of location of TCU and seeing if it has a red light shining from the fiberoptic cable? Then just connect the loop the the cable and by pass the TCU. What happens it the light is there?? Again everyone I'm.new to this please be gentle I am now very desperate. Any help guys and girls would be so much appreciated I want to get back to driving my pride and joy asap.

Hi Rob

Welcome to the Forum

Does your car have Business or Professional audio set up? To be sure look at BMW Vin Decoder put the last 7 digits of your Vin into the search box and it will bring up the build sheet for your car.

Then look at www.newtis.info This is a BMW Technical information site (BMW Dealers use the same information) Vin time again then you should be able to find all you need for Test Replacement and Repair.

Use www.realoem.com to find the correct part numbers for all components if you are replacing stuff.

Often you will be told that items need "coding" don't be scared off. Parts will still work you will just get a tamper dot in the display you probably have one already from the aftermarket Cd Changer (I take it you mean a 6 Cd Changer mounted in the boot) a BMW specific diagnostic program will find the problem without guess work and you can also program units to your chassis. I use BMW 1.4.0 on an old laptop it only cost about £10 and I find it invaluable.

Dave